Make lock counter info independent of the locks being counted

This allows us to enable/disable lock counting at will, and greatly improves
the performance of erts_debug:lock_counters/1 since we no longer have to
worry about the lock counters "dying" while we're enumerating them.

OTP-14412

16 files changed, 1690 insertions, 903 deletions

diff --git a/erts/emulator/Makefile.in b/erts/emulator/Makefile.in
index 254e59f2c7..ecbf76595b 100644
--- a/erts/emulator/Makefile.in
+++ b/erts/emulator/Makefile.in
@@ -116,6 +116,7 @@ ifeq ($(TYPE),lcnt)
 PURIFY =
 TYPEMARKER = .lcnt
 TYPE_FLAGS = @CFLAGS@ -DERTS_ENABLE_LOCK_COUNT
+ENABLE_ALLOC_TYPE_VARS += lcnt
 else
 
 ifeq ($(TYPE),frmptr)
diff --git a/erts/emulator/beam/erl_alloc.types b/erts/emulator/beam/erl_alloc.types
index 8a23a1526e..c155630765 100644
--- a/erts/emulator/beam/erl_alloc.types
+++ b/erts/emulator/beam/erl_alloc.types
@@ -368,6 +368,13 @@ type	SSB		SHORT_LIVED	PROCESSES	ssb
 
 +endif
 
++if lcnt
+
+type    LCNT_CARRIER   STANDARD    SYSTEM  lcnt_lock_info_carrier
+type    LCNT_VECTOR SHORT_LIVED SYSTEM lcnt_lock_info_vector
+
++endif
+
 type	DEBUG	        SHORT_LIVED	SYSTEM          debugging
 
 type	DDLL_PROCESS	STANDARD	SYSTEM		ddll_processes
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 5fc70dfc02..8f7de32f12 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -4430,48 +4430,108 @@ BIF_RETTYPE erts_debug_set_internal_state_2(BIF_ALIST_2)
 }
 
 #ifdef ERTS_ENABLE_LOCK_COUNT
+
+typedef struct lcnt_lock_info_vector_ {
+    erts_lcnt_lock_info_t **elements;
+    size_t size;
+} lcnt_lock_info_vector_t;
+
+static lcnt_lock_info_vector_t lcnt_build_lock_info_vector(erts_lcnt_lock_info_list_t *list) {
+    erts_lcnt_lock_info_t *iterator;
+    lcnt_lock_info_vector_t result;
+    size_t allocated_entries;
+
+    allocated_entries = 64;
+    result.size = 0;
+
+    result.elements = erts_alloc(ERTS_ALC_T_LCNT_VECTOR,
+        allocated_entries * sizeof(erts_lcnt_lock_info_t*));
+
+    iterator = NULL;
+    while(erts_lcnt_iterate_list(list, &iterator)) {
+        erts_lcnt_retain_lock_info(iterator);
+
+        result.elements[result.size++] = iterator;
+
+        if(result.size >= allocated_entries) {
+            allocated_entries *= 2;
+
+            result.elements = erts_realloc(ERTS_ALC_T_LCNT_VECTOR, result.elements,
+                allocated_entries * sizeof(erts_lcnt_lock_info_t*));
+        }
+    }
+
+    return result;
+}
+
+static void lcnt_destroy_lock_info_vector(lcnt_lock_info_vector_t *vector) {
+    size_t i;
+
+    for(i = 0; i < vector->size; i++) {
+        erts_lcnt_release_lock_info(vector->elements[i]);
+    }
+
+    erts_free(ERTS_ALC_T_LCNT_VECTOR, vector->elements);
+}
+
+/* The size of an integer is not guaranteed to be constant since we're walking
+ * over live data, and may cross over into bignum territory between size calc
+ * and the actual build. This takes care of that through always assuming the
+ * worst, but needs to be fixed up with HRelease once the final term has been
+ * built. */
+static ERTS_INLINE Eterm bld_unstable_uint64(Uint **hpp, Uint *szp, Uint64 ui) {
+    Eterm res = THE_NON_VALUE;
+
+    if(szp) {
+        *szp += ERTS_UINT64_HEAP_SIZE(~((Uint64) 0));
+    }
+
+    if(hpp) {
+        if (IS_USMALL(0, ui)) {
+            res = make_small(ui);
+        } else {
+            res = erts_uint64_to_big(ui, hpp);
+        }
+    }
+
+    return res;
+}
+
 static Eterm lcnt_build_lock_stats_term(Eterm **hpp, Uint *szp, erts_lcnt_lock_stats_t *stats, Eterm res) {
-    Uint tries = 0, colls = 0;
-    unsigned long timer_s = 0, timer_ns = 0, timer_n = 0;
-    unsigned int  line = 0;
     unsigned int  i;
-    
+    const char *file;
+
     Eterm af, uil;
     Eterm uit, uic;
     Eterm uits, uitns, uitn;
     Eterm tt, tstat, tloc, t;
     Eterm thist, vhist[ERTS_LCNT_HISTOGRAM_SLOT_SIZE];
-	
+
     /* term:
-     * [{{file, line}, {tries, colls, {seconds, nanoseconds, n_blocks}},
-     *   { .. histogram .. }]
-     */
+        * [{{file, line}, {tries, colls, {seconds, nanoseconds, n_blocks}},
+        *   { .. histogram .. }]
+        */
 
-    tries = (Uint) ethr_atomic_read(&stats->tries);
-    colls = (Uint) ethr_atomic_read(&stats->colls);
-   
-    line     = stats->line; 
-    timer_s  = stats->timer.s;
-    timer_ns = stats->timer.ns;
-    timer_n  = stats->timer_n;
-   
-    af    = erts_atom_put((byte *)stats->file, strlen(stats->file), ERTS_ATOM_ENC_LATIN1, 1);
-    uil   = erts_bld_uint( hpp, szp, line);
+    file = stats->file ? stats->file : "undefined";
+
+    af    = erts_atom_put((byte *)file, strlen(file), ERTS_ATOM_ENC_LATIN1, 1);
+    uil   = erts_bld_uint( hpp, szp, stats->line);
     tloc  = erts_bld_tuple(hpp, szp, 2, af, uil);
-    
-    uit   = erts_bld_uint( hpp, szp, tries);
-    uic   = erts_bld_uint( hpp, szp, colls);
 
-    uits  = erts_bld_uint( hpp, szp, timer_s);
-    uitns = erts_bld_uint( hpp, szp, timer_ns);
-    uitn  = erts_bld_uint( hpp, szp, timer_n);
+    uit   = bld_unstable_uint64(hpp, szp, (Uint)ethr_atomic_read(&stats->attempts));
+    uic   = bld_unstable_uint64(hpp, szp, (Uint)ethr_atomic_read(&stats->collisions));
+
+    uits  = bld_unstable_uint64(hpp, szp, stats->total_time_waited.s);
+    uitns = bld_unstable_uint64(hpp, szp, stats->total_time_waited.ns);
+    uitn  = bld_unstable_uint64(hpp, szp, stats->times_waited);
     tt    = erts_bld_tuple(hpp, szp, 3, uits, uitns, uitn);
 
     tstat = erts_bld_tuple(hpp, szp, 3, uit, uic, tt);
 
     for(i = 0; i < ERTS_LCNT_HISTOGRAM_SLOT_SIZE; i++) {
-	vhist[i] = erts_bld_uint(hpp, szp, stats->hist.ns[i]);
+        vhist[i] = bld_unstable_uint64(hpp, szp, stats->wait_time_histogram.ns[i]);
     }
+
     thist  = erts_bld_tuplev(hpp, szp, ERTS_LCNT_HISTOGRAM_SLOT_SIZE, vhist);
 
     t   = erts_bld_tuple(hpp, szp, 3, tloc, tstat, thist);
@@ -4480,150 +4540,165 @@ static Eterm lcnt_build_lock_stats_term(Eterm **hpp, Uint *szp, erts_lcnt_lock_s
     return res;
 }
 
-static Eterm lcnt_build_lock_term(Eterm **hpp, Uint *szp, erts_lcnt_lock_t *lock, Eterm res) {
+static Eterm lcnt_pretty_print_lock_id(erts_lcnt_lock_info_t *info) {
+    Eterm id = info->id;
+
+    if(info->flag & ERTS_LCNT_LT_ALLOC) {
+        /* Use allocator type names as id's for allocator locks. This blatantly
+         * assumes that all locks in this category are identified by their
+         * allocator number. */
+        const char *ltype = (const char*)ERTS_ALC_A2AD(signed_val(info->id));
+        id = erts_atom_put((byte*)ltype, strlen(ltype), ERTS_ATOM_ENC_LATIN1, 1);
+    } else if(info->flag & ERTS_LCNT_LT_PROCLOCK) {
+        /* Use registered names as id's for process locks if available. Thread
+         * progress is delayed since we may be running on a dirty scheduler. */
+        ErtsThrPrgrDelayHandle delay_handle;
+        Process *process;
+
+        delay_handle = erts_thr_progress_unmanaged_delay();
+
+        process = erts_proc_lookup(info->id);
+        if (process && process->common.u.alive.reg) {
+            id = process->common.u.alive.reg->name;
+        }
+
+        erts_thr_progress_unmanaged_continue(delay_handle);
+    }
+
+    return id;
+}
+
+static Eterm lcnt_build_lock_term(Eterm **hpp, Uint *szp, erts_lcnt_lock_info_t *info, Eterm res) {
     Eterm name, type, id, stats = NIL, t;
-    Process *proc = NULL;
-    char *ltype;
+    const char *ltype;
     int i;
     
     /* term:
      * [{name, id, type, stats()}] 
      */
-	
-    ASSERT(lock->name);
+
+    ASSERT(info->name);
     
-    ltype = erts_lcnt_lock_type(lock->flag);
+    ltype = erts_lcnt_lock_type(info->flag);
     
     ASSERT(ltype);
     
-    type  = erts_atom_put((byte *)ltype, strlen(ltype), ERTS_ATOM_ENC_LATIN1, 1);
-    name  = erts_atom_put((byte *)lock->name, strlen(lock->name), ERTS_ATOM_ENC_LATIN1, 1);
-
-    if (lock->flag & ERTS_LCNT_LT_ALLOC) {
-	/* use allocator types names as id's for allocator locks */
-	ltype = (char *) ERTS_ALC_A2AD(signed_val(lock->id));
-	id    = erts_atom_put((byte *)ltype, strlen(ltype), ERTS_ATOM_ENC_LATIN1, 1);
-    } else if (lock->flag & ERTS_LCNT_LT_PROCLOCK) {
-	/* use registered names as id's for process locks if available */
-	proc  = erts_proc_lookup(lock->id);
-	if (proc && proc->common.u.alive.reg) {
-	    id = proc->common.u.alive.reg->name;
-	} else {
-	    /* otherwise use process id */
-	    id = lock->id;
-	}
+    type  = erts_atom_put((byte*)ltype, strlen(ltype), ERTS_ATOM_ENC_LATIN1, 1);
+    name  = erts_atom_put((byte*)info->name, strlen(info->name), ERTS_ATOM_ENC_LATIN1, 1);
+
+    /* Only attempt to resolve ids when actually emitting the term. This ought
+     * to be safe since all immediates are the same size. */
+    if(hpp != NULL) {
+        id = lcnt_pretty_print_lock_id(info);
     } else {
-	id = lock->id;
+        id = NIL;
     }
 
-    for (i = 0; i < lock->n_stats; i++) {
-	stats = lcnt_build_lock_stats_term(hpp, szp, &(lock->stats[i]), stats);
+    /* info->location_count is ignored since it can be changed at any time. */
+    for(i = 0; i < ERTS_LCNT_MAX_LOCK_LOCATIONS; i++) {
+        stats = lcnt_build_lock_stats_term(hpp, szp, &(info->location_stats[i]), stats);
     }
 
     t   = erts_bld_tuple(hpp, szp, 4, name, id, type, stats);
-    res = erts_bld_cons( hpp, szp, t, res);
+    res = erts_bld_cons(hpp, szp, t, res);
 
     return res;
 }
 
-static Eterm lcnt_build_result_term(Eterm **hpp, Uint *szp, erts_lcnt_data_t *data, Eterm res) {
+static Eterm lcnt_build_result_term(Eterm **hpp, Uint *szp, erts_lcnt_time_t *duration,
+                                    lcnt_lock_info_vector_t *current_locks,
+                                    lcnt_lock_info_vector_t *deleted_locks, Eterm res) {
     Eterm dts, dtns, tdt, adur, tdur, aloc, lloc = NIL, tloc;
-    erts_lcnt_lock_t *lock = NULL;
+
+    size_t i;
+
     char *str_duration = "duration";
     char *str_locks    = "locks";
-    
+
     /* term:
      * [{'duration', {seconds, nanoseconds}}, {'locks', locks()}]
      */
-   
+
     /* duration tuple */ 
-    dts  = erts_bld_uint( hpp, szp, data->duration.s);
-    dtns = erts_bld_uint( hpp, szp, data->duration.ns);
+    dts  = bld_unstable_uint64(hpp, szp, duration->s);
+    dtns = bld_unstable_uint64(hpp, szp, duration->ns);
     tdt  = erts_bld_tuple(hpp, szp, 2, dts, dtns);
-    
+
     adur = erts_atom_put((byte *)str_duration, strlen(str_duration), ERTS_ATOM_ENC_LATIN1, 1);
     tdur = erts_bld_tuple(hpp, szp, 2, adur, tdt);
    
     /* lock tuple */
     
     aloc = erts_atom_put((byte *)str_locks, strlen(str_locks), ERTS_ATOM_ENC_LATIN1, 1);
-    	
-    for (lock = data->current_locks->head; lock != NULL ; lock = lock->next ) {
-	lloc = lcnt_build_lock_term(hpp, szp, lock, lloc);
+
+    for(i = 0; i < current_locks->size; i++) {
+        lloc = lcnt_build_lock_term(hpp, szp, current_locks->elements[i], lloc);
     }
-    
-    for (lock = data->deleted_locks->head; lock != NULL ; lock = lock->next ) {
-	lloc = lcnt_build_lock_term(hpp, szp, lock, lloc);
+
+    for(i = 0; i < deleted_locks->size; i++) {
+        lloc = lcnt_build_lock_term(hpp, szp, deleted_locks->elements[i], lloc);
     }
-    
+
     tloc = erts_bld_tuple(hpp, szp, 2, aloc, lloc);
-    
-    res  = erts_bld_cons( hpp, szp, tloc, res);          
-    res  = erts_bld_cons( hpp, szp, tdur, res);          
+
+    res  = erts_bld_cons(hpp, szp, tloc, res);
+    res  = erts_bld_cons(hpp, szp, tdur, res);
 
     return res;
-}    
+}
+
 #endif
 
 BIF_RETTYPE erts_debug_lock_counters_1(BIF_ALIST_1)
 {
-#ifdef ERTS_ENABLE_LOCK_COUNT
-    Eterm res = NIL;
-#endif
-
-
+#ifndef ERTS_ENABLE_LOCK_COUNT
     if (BIF_ARG_1 == am_enabled) {
-#ifdef ERTS_ENABLE_LOCK_COUNT
-	BIF_RET(am_true);
-#else
-	BIF_RET(am_false);
-#endif
+        BIF_RET(am_false);
     }
-#ifdef ERTS_ENABLE_LOCK_COUNT
 
-    else if (BIF_ARG_1 == am_info) {
-	erts_lcnt_data_t *data; 
-	Uint hsize = 0;
-	Uint *szp;
-    	Eterm* hp;
+    BIF_ERROR(BIF_P, BADARG);
+#else
 
-	erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
-	erts_smp_thr_progress_block();
+    if (BIF_ARG_1 == am_enabled) {
+       BIF_RET(am_true);
+    } else if (BIF_ARG_1 == am_info) {
+        lcnt_lock_info_vector_t current_locks, deleted_locks;
+        erts_lcnt_data_t data;
 
-	erts_lcnt_set_rt_opt(ERTS_LCNT_OPT_SUSPEND);
-	data = erts_lcnt_get_data();
+        Eterm *term_heap_start, *term_heap_end;
+        Uint term_heap_size = 0;
+        Eterm result;
 
-	/* calculate size */
+        data = erts_lcnt_get_data();
 
-	szp = &hsize;
-	lcnt_build_result_term(NULL, szp, data, NIL);
+        current_locks = lcnt_build_lock_info_vector(data.current_locks);
+        deleted_locks = lcnt_build_lock_info_vector(data.deleted_locks);
 
-	/* alloc and build */
+        lcnt_build_result_term(NULL, &term_heap_size, &data.duration,
+            &current_locks, &deleted_locks, NIL);
 
-	hp = HAlloc(BIF_P, hsize);
+        term_heap_start = HAlloc(BIF_P, term_heap_size);
+        term_heap_end = term_heap_start;
 
-	res = lcnt_build_result_term(&hp, NULL, data, res);
-	
-	erts_lcnt_clear_rt_opt(ERTS_LCNT_OPT_SUSPEND);
+        result = lcnt_build_result_term(&term_heap_end, NULL,
+            &data.duration, &current_locks, &deleted_locks, NIL);
 
-	erts_smp_thr_progress_unblock();
-	erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_MAIN);
-	
-	BIF_RET(res);
-    } else if (BIF_ARG_1 == am_clear) {
-	erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
-	erts_smp_thr_progress_block();
+        HRelease(BIF_P, term_heap_start + term_heap_size, term_heap_end);
 
-	erts_lcnt_clear_counters();
+        lcnt_destroy_lock_info_vector(&current_locks);
+        lcnt_destroy_lock_info_vector(&deleted_locks);
 
-	erts_smp_thr_progress_unblock();
-	erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_MAIN);
+        BIF_RET(result);
+    } else if (BIF_ARG_1 == am_clear) {
+        erts_lcnt_clear_counters();
 
-	BIF_RET(am_ok);
+        BIF_RET(am_ok);
     } else if (is_tuple(BIF_ARG_1)) {
         Eterm* ptr = tuple_val(BIF_ARG_1);
 
         if ((arityval(ptr[0]) == 2) && (ptr[2] == am_false || ptr[2] == am_true)) {
+           Eterm res;
+
             int lock_opt = 0, enable = (ptr[2] == am_true) ? 1 : 0;
             if (ERTS_IS_ATOM_STR("copy_save", ptr[1])) {
                 lock_opt = ERTS_LCNT_OPT_COPYSAVE;
@@ -4631,35 +4706,41 @@ BIF_RETTYPE erts_debug_lock_counters_1(BIF_ALIST_1)
                 lock_opt = ERTS_LCNT_OPT_PROCLOCK;
             } else if (ERTS_IS_ATOM_STR("port_locks", ptr[1])) {
                 lock_opt = ERTS_LCNT_OPT_PORTLOCK;
-            } else if (ERTS_IS_ATOM_STR("suspend", ptr[1])) {
-                lock_opt = ERTS_LCNT_OPT_SUSPEND;
             } else if (ERTS_IS_ATOM_STR("location", ptr[1])) {
                 lock_opt = ERTS_LCNT_OPT_LOCATION;
             } else {
                 BIF_ERROR(BIF_P, BADARG);
             }
 
+            if (enable) {
+                res = erts_lcnt_set_rt_opt(lock_opt) ? am_true : am_false;
+            } else {
+                res = erts_lcnt_clear_rt_opt(lock_opt) ? am_true : am_false;
+            }
+
+#ifdef ERTS_SMP
+            /* FIXME: make this non-blocking. */
             erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
             erts_smp_thr_progress_block();
+#endif
 
-            if (enable) res = erts_lcnt_set_rt_opt(lock_opt) ? am_true : am_false;
-            else res = erts_lcnt_clear_rt_opt(lock_opt) ? am_true : am_false;
-            
-#ifdef ERTS_SMP
             if (res != ptr[2] && lock_opt == ERTS_LCNT_OPT_PORTLOCK) {
                 erts_lcnt_enable_io_lock_count(enable);
             } else if (res != ptr[2] && lock_opt == ERTS_LCNT_OPT_PROCLOCK) {
                 erts_lcnt_enable_proc_lock_count(enable);
             }
-#endif
-            erts_smp_thr_progress_unblock();
+
+#ifdef ERTS_SMP
             erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_MAIN);
+            erts_smp_thr_progress_unblock();
+#endif
+
             BIF_RET(res);
         }
-    } 
+    }
 
-#endif 
     BIF_ERROR(BIF_P, BADARG);
+#endif
 }
 
 static void os_info_init(void)
diff --git a/erts/emulator/beam/erl_dirty_bif.tab b/erts/emulator/beam/erl_dirty_bif.tab
index 69421dcfcc..94d8589779 100644
--- a/erts/emulator/beam/erl_dirty_bif.tab
+++ b/erts/emulator/beam/erl_dirty_bif.tab
@@ -46,6 +46,8 @@
 dirty-cpu erts_debug:dirty_cpu/2
 dirty-io erts_debug:dirty_io/2
 
+dirty-cpu erts_debug:lock_counters/1
+
 # --- TEST of Dirty BIF functionality ---
 #  Functions below will execute on dirty schedulers when emulator has
 #  been configured for testing dirty schedulers. This is used for test
diff --git a/erts/emulator/beam/erl_drv_thread.c b/erts/emulator/beam/erl_drv_thread.c
index 0e6aadf568..3b68abe5d7 100644
--- a/erts/emulator/beam/erl_drv_thread.c
+++ b/erts/emulator/beam/erl_drv_thread.c
@@ -55,7 +55,7 @@ fatal_error(int err, char *func)
 struct ErlDrvMutex_ {
     ethr_mutex mtx;
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_lock_t lcnt;
+    erts_lcnt_ref_t lcnt;
 #endif
     char *name;
 };
@@ -68,7 +68,7 @@ struct ErlDrvCond_ {
 struct ErlDrvRWLock_ {
     ethr_rwmutex rwmtx;
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_lock_t lcnt;
+    erts_lcnt_ref_t lcnt;
 #endif
     char *name;
 };
@@ -176,7 +176,8 @@ erl_drv_mutex_create(char *name)
 	    dmtx->name = no_name;
 	}
 #ifdef ERTS_ENABLE_LOCK_COUNT
-        erts_lcnt_init_lock(&dmtx->lcnt, dmtx->name, ERTS_LCNT_LT_MUTEX);
+    erts_lcnt_init_ref(&dmtx->lcnt);
+    erts_lcnt_install_new_lock_info(&dmtx->lcnt, dmtx->name, ERTS_LCNT_LT_MUTEX);
 #endif
     }
     return dmtx;
@@ -191,7 +192,7 @@ erl_drv_mutex_destroy(ErlDrvMutex *dmtx)
 #ifdef USE_THREADS
     int res;
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_destroy_lock(&dmtx->lcnt);
+    erts_lcnt_uninstall(&dmtx->lcnt);
 #endif
     res = dmtx ? ethr_mutex_destroy(&dmtx->mtx) : EINVAL;
     if (res != 0)
@@ -368,7 +369,8 @@ erl_drv_rwlock_create(char *name)
 	    drwlck->name = no_name;
 	}
 #ifdef ERTS_ENABLE_LOCK_COUNT
-        erts_lcnt_init_lock(&drwlck->lcnt, drwlck->name, ERTS_LCNT_LT_RWMUTEX);
+    erts_lcnt_init_ref(&drwlck->lcnt);
+    erts_lcnt_install_new_lock_info(&drwlck->lcnt, drwlck->name, ERTS_LCNT_LT_RWMUTEX);
 #endif
     }
     return drwlck;
@@ -383,7 +385,7 @@ erl_drv_rwlock_destroy(ErlDrvRWLock *drwlck)
 #ifdef USE_THREADS
     int res;
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_destroy_lock(&drwlck->lcnt);
+    erts_lcnt_uninstall(&drwlck->lcnt);
 #endif
     res = drwlck ? ethr_rwmutex_destroy(&drwlck->rwmtx) : EINVAL;
     if (res != 0)
diff --git a/erts/emulator/beam/erl_lock_count.c b/erts/emulator/beam/erl_lock_count.c
index aee9796171..2cf59aa367 100644
--- a/erts/emulator/beam/erl_lock_count.c
+++ b/erts/emulator/beam/erl_lock_count.c
@@ -1,7 +1,7 @@
 /*
  * %CopyrightBegin%
  *
- * Copyright Ericsson AB 2008-2016. All Rights Reserved.
+ * Copyright Ericsson AB 2008-2017. All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,51 +18,30 @@
  * %CopyrightEnd%
  */
 
-/*
- * Description:	Statistics for locks.
- *
- * Author:	Björn-Egil Dahlberg
- * Date:	2008-07-03
- */
-
 #ifdef HAVE_CONFIG_H
 #  include "config.h"
 #endif
 
-/* Needed for VxWorks va_arg */
-#include "sys.h"
-
 #ifdef ERTS_ENABLE_LOCK_COUNT
 
+#include "sys.h"
+
 #include "erl_lock_count.h"
-#include "ethread.h"
-#include "erl_term.h"
-#include "atom.h"
-#include <stdio.h>
+#include "erl_thr_progress.h"
 
-/* globals, dont access these without locks or blocks */
+#define LCNT_MAX_CARRIER_ENTRIES 255
 
-ethr_mutex lcnt_data_lock;
-erts_lcnt_data_t *erts_lcnt_data;
-Uint16 erts_lcnt_rt_options;
-erts_lcnt_time_t timer_start;
-const char *str_undefined = "undefined";
+/* - Exported global - */
 
-static ethr_tsd_key lcnt_thr_data_key;
-static int lcnt_n_thr;
-static erts_lcnt_thread_data_t *lcnt_thread_data[2048];
+Uint16 erts_lcnt_rt_options = ERTS_LCNT_OPT_PROCLOCK | ERTS_LCNT_OPT_LOCATION;
 
-/* local functions */
+/* - Locals that are shared with the header implementation - */
 
-static ERTS_INLINE void lcnt_lock(void) {
-    ethr_mutex_lock(&lcnt_data_lock);
-}
+int lcnt_initialization_completed__ = 0;
 
-static ERTS_INLINE void lcnt_unlock(void) {
-    ethr_mutex_unlock(&lcnt_data_lock);
-}
+ethr_tsd_key lcnt_thr_data_key__;
 
-const int log2_tab64[64] = {
+const int lcnt_log2_tab64__[64] = {
     63,  0, 58,  1, 59, 47, 53,  2,
     60, 39, 48, 27, 54, 33, 42,  3,
     61, 51, 37, 40, 49, 18, 28, 20,
@@ -72,99 +51,52 @@ const int log2_tab64[64] = {
     56, 45, 25, 31, 35, 16,  9, 12,
     44, 24, 15,  8, 23,  7,  6,  5};
 
-static ERTS_INLINE int lcnt_log2(Uint64 v) {
-    v |= v >> 1;
-    v |= v >> 2;
-    v |= v >> 4;
-    v |= v >> 8;
-    v |= v >> 16;
-    v |= v >> 32;
-    return log2_tab64[((Uint64)((v - (v >> 1))*0x07EDD5E59A4E28C2)) >> 58];
-}
-
-static char* lcnt_lock_type(Uint16 flag) {
-    switch(flag & ERTS_LCNT_LT_ALL) {
-        case ERTS_LCNT_LT_SPINLOCK:   return "spinlock";
-        case ERTS_LCNT_LT_RWSPINLOCK: return "rw_spinlock";
-        case ERTS_LCNT_LT_MUTEX:      return "mutex";
-        case ERTS_LCNT_LT_RWMUTEX:    return "rw_mutex";
-        case ERTS_LCNT_LT_PROCLOCK:   return "proclock";
-        default:                      return "";
-    }
-}
+/* - Local variables - */
 
-static void lcnt_clear_stats(erts_lcnt_lock_stats_t *stats) {
-    ethr_atomic_set(&stats->tries, 0);
-    ethr_atomic_set(&stats->colls, 0);
-    stats->timer.s  = 0;
-    stats->timer.ns = 0;
-    stats->timer_n  = 0;
-    stats->file     = (char *)str_undefined;
-    stats->line     = 0;
-    sys_memzero(stats->hist.ns, sizeof(stats->hist.ns));
-}
+static erts_lcnt_lock_info_list_t lcnt_current_lock_list;
+static erts_lcnt_lock_info_list_t lcnt_deleted_lock_list;
 
-static void lcnt_time(erts_lcnt_time_t *time) {
-    /*
-     * erts_sys_hrtime() is the highest resolution
-     * we could find, it may or may not be monotonic...
-     */
-    ErtsMonotonicTime mtime = erts_sys_hrtime();
-    time->s  = (unsigned long) (mtime / 1000000000LL);
-    time->ns = (unsigned long) (mtime - 1000000000LL*time->s);
-}
+static erts_lcnt_time_t lcnt_timer_start;
 
-static void lcnt_time_diff(erts_lcnt_time_t *d, erts_lcnt_time_t *t1, erts_lcnt_time_t *t0) {
-    long ds;
-    long dns;
+/* local functions */
 
-    ds  = t1->s  - t0->s;
-    dns = t1->ns - t0->ns;
+static void lcnt_clear_stats(erts_lcnt_lock_info_t *info) {
+    size_t i;
 
-    /* the difference should not be able to get bigger than 1 sec in ns*/
+    for(i = 0; i < ERTS_LCNT_MAX_LOCK_LOCATIONS; i++) {
+        erts_lcnt_lock_stats_t *stats = &info->location_stats[i];
 
-    if (dns < 0) {
-        ds  -= 1;
-        dns += 1000000000LL;
-    }
+        sys_memzero(&stats->wait_time_histogram, sizeof(stats->wait_time_histogram));
 
-    ASSERT(ds >= 0);
+        stats->total_time_waited.s = 0;
+        stats->total_time_waited.ns = 0;
 
-    d->s  = ds;
-    d->ns = dns;
-}
+        stats->times_waited = 0;
 
-/* difference d must be non-negative */
+        stats->file = NULL;
+        stats->line = 0;
 
-static void lcnt_time_add(erts_lcnt_time_t *t, erts_lcnt_time_t *d) {
-    t->s  += d->s;
-    t->ns += d->ns;
+        ethr_atomic_set(&stats->attempts, 0);
+        ethr_atomic_set(&stats->collisions, 0);
+    }
 
-    t->s  += t->ns / 1000000000LL;
-    t->ns  = t->ns % 1000000000LL;
+    info->location_count = 1;
 }
 
-static erts_lcnt_thread_data_t *lcnt_thread_data_alloc(void) {
-    erts_lcnt_thread_data_t *eltd;
+static lcnt_thread_data_t__ *lcnt_thread_data_alloc(void) {
+    lcnt_thread_data_t__ *eltd =
+        (lcnt_thread_data_t__*)malloc(sizeof(lcnt_thread_data_t__));
 
-    eltd = (erts_lcnt_thread_data_t*)malloc(sizeof(erts_lcnt_thread_data_t));
-    if (!eltd) {
-        ERTS_INTERNAL_ERROR("Lock counter failed to allocate memory!");
+    if(!eltd) {
+        ERTS_INTERNAL_ERROR("Failed to allocate lcnt thread data.");
     }
+
     eltd->timer_set = 0;
     eltd->lock_in_conflict = 0;
 
-    eltd->id = lcnt_n_thr++;
-    /* set thread data to array */
-    lcnt_thread_data[eltd->id] = eltd;
-
     return eltd;
 }
 
-static erts_lcnt_thread_data_t *lcnt_get_thread_data(void) {
-    return (erts_lcnt_thread_data_t *)ethr_tsd_get(lcnt_thr_data_key);
-}
-
 /* debug */
 
 #if 0
@@ -175,472 +107,391 @@ static char* lock_opt(Uint16 flag) {
     return "--";
 }
 
-static void print_lock_x(erts_lcnt_lock_t *lock, Uint16 flag, char *action) {
-    erts_aint_t w_state, r_state;
+static void print_lock_x(erts_lcnt_lock_info_t *info, Uint16 flag, char *action) {
+    ethr_sint_t w_state, r_state;
     char *type;
 
-    if (strcmp(lock->name, "run_queue") != 0) return;
-    type = lcnt_lock_type(lock->flag);
-    r_state = ethr_atomic_read(&lock->r_state);
-    w_state = ethr_atomic_read(&lock->w_state);
+    if (strcmp(info->name, "run_queue") != 0) return;
+    type = erts_lcnt_lock_type(info->flag);
+    r_state = ethr_atomic_read(&info->r_state);
+    w_state = ethr_atomic_read(&info->w_state);
 
-    if (lock->flag & flag) {
+    if (info->flag & flag) {
         erts_fprintf(stderr,"%10s [%24s] [r/w state %4ld/%4ld] %2s id %T\r\n",
                 action,
-                lock->name,
+                info->name,
                 r_state,
                 w_state,
                 type,
-                lock->id);
+                info->id);
     }
 }
 #endif
 
-static erts_lcnt_lock_stats_t *lcnt_get_lock_stats(erts_lcnt_lock_t *lock, char *file, unsigned int line) {
-    unsigned int i;
-    erts_lcnt_lock_stats_t *stats = NULL;
-
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_LOCATION) {
-        for (i = 0; i < lock->n_stats; i++) {
-            if ((lock->stats[i].file == file) && (lock->stats[i].line == line)) {
-                return &(lock->stats[i]);
-            }
-        }
-        if (lock->n_stats < ERTS_LCNT_MAX_LOCK_LOCATIONS) {
-            stats = &lock->stats[lock->n_stats];
-            lock->n_stats++;
-            stats->file = file;
-            stats->line = line;
-            return stats;
-        }
-    }
-    return &lock->stats[0];
+/* - List operations -
+ *
+ * Info entries are kept in a doubly linked list where each entry is locked
+ * with its neighbors rather than a global lock. Deletion is rather quick, but
+ * insertion is still serial since the head becomes a de facto global lock.
+ *
+ * We rely on ad-hoc spinlocks to avoid "recursing" into this module. */
+
+#define LCNT_SPINLOCK_YIELD_ITERATIONS 50
+
+#define LCNT_SPINLOCK_HELPER_INIT \
+    Uint failed_spin_count = 0;
+
+#define LCNT_SPINLOCK_HELPER_YIELD \
+    do { \
+        failed_spin_count++; \
+        if(!(failed_spin_count % LCNT_SPINLOCK_YIELD_ITERATIONS)) { \
+            erts_thr_yield(); \
+        } else { \
+            ERTS_SPIN_BODY; \
+        } \
+    } while(0)
+
+static void lcnt_unlock_list_entry(erts_lcnt_lock_info_t *info) {
+    ethr_atomic32_set_relb(&info->lock, 0);
 }
 
-static void lcnt_update_stats_hist(erts_lcnt_hist_t *hist, erts_lcnt_time_t *time_wait) {
-    int idx;
-    unsigned long r;
+static int lcnt_try_lock_list_entry(erts_lcnt_lock_info_t *info) {
+    return ethr_atomic32_cmpxchg_acqb(&info->lock, 1, 0) == 0;
+}
 
-    if (time_wait->s > 0 || time_wait->ns > ERTS_LCNT_HISTOGRAM_MAX_NS) {
-        idx = ERTS_LCNT_HISTOGRAM_SLOT_SIZE - 1;
-    } else {
-        r = time_wait->ns >> ERTS_LCNT_HISTOGRAM_RSHIFT;
-        if (r) idx = lcnt_log2(r);
-        else idx = 0;
+static void lcnt_lock_list_entry(erts_lcnt_lock_info_t *info) {
+    LCNT_SPINLOCK_HELPER_INIT;
+
+    while(!lcnt_try_lock_list_entry(info)) {
+        LCNT_SPINLOCK_HELPER_YIELD;
     }
-    hist->ns[idx]++;
 }
 
-static void lcnt_update_stats(erts_lcnt_lock_stats_t *stats, int lock_in_conflict,
-        erts_lcnt_time_t *time_wait) {
+static void lcnt_lock_list_entry_with_neighbors(erts_lcnt_lock_info_t *info) {
+    LCNT_SPINLOCK_HELPER_INIT;
 
-    ethr_atomic_inc(&stats->tries);
+    for(;;) {
+        if(!lcnt_try_lock_list_entry(info))
+            goto retry_after_entry_failed;
+        if(!lcnt_try_lock_list_entry(info->next))
+            goto retry_after_next_failed;
+        if(!lcnt_try_lock_list_entry(info->prev))
+            goto retry_after_prev_failed;
 
-    if (lock_in_conflict)
-        ethr_atomic_inc(&stats->colls);
+        return;
 
-    if (time_wait) {
-        lcnt_time_add(&(stats->timer), time_wait);
-        stats->timer_n++;
-        lcnt_update_stats_hist(&stats->hist,time_wait);
+    retry_after_prev_failed:
+        lcnt_unlock_list_entry(info->next);
+    retry_after_next_failed:
+        lcnt_unlock_list_entry(info);
+    retry_after_entry_failed:
+        LCNT_SPINLOCK_HELPER_YIELD;
     }
 }
 
-/* interface */
+static void lcnt_unlock_list_entry_with_neighbors(erts_lcnt_lock_info_t *info) {
+    lcnt_unlock_list_entry(info->prev);
+    lcnt_unlock_list_entry(info->next);
+    lcnt_unlock_list_entry(info);
+}
 
-void erts_lcnt_init() {
-    erts_lcnt_thread_data_t *eltd = NULL;
+static void lcnt_insert_list_entry(erts_lcnt_lock_info_list_t *list, erts_lcnt_lock_info_t *info) {
+    erts_lcnt_lock_info_t *next, *prev;
 
-    /* init lock */
-    if (ethr_mutex_init(&lcnt_data_lock) != 0) abort();
+    prev = &list->head;
 
-    /* init tsd */
-    lcnt_n_thr = 0;
-    ethr_tsd_key_create(&lcnt_thr_data_key, "lcnt_data");
+    lcnt_lock_list_entry(prev);
 
-    lcnt_lock();
+    next = prev->next;
 
-    erts_lcnt_rt_options = ERTS_LCNT_OPT_LOCATION | ERTS_LCNT_OPT_PROCLOCK;
-    eltd = lcnt_thread_data_alloc();
-    ethr_tsd_set(lcnt_thr_data_key, eltd);
+    lcnt_lock_list_entry(next);
 
-    /* init lcnt structure */
-    erts_lcnt_data = (erts_lcnt_data_t*)malloc(sizeof(erts_lcnt_data_t));
-    if (!erts_lcnt_data) {
-        ERTS_INTERNAL_ERROR("Lock counter failed to allocate memory!");
-    }
-    erts_lcnt_data->current_locks = erts_lcnt_list_init();
-    erts_lcnt_data->deleted_locks = erts_lcnt_list_init();
+    info->next = next;
+    info->prev = prev;
 
-    lcnt_unlock();
+    prev->next = info;
+    next->prev = info;
 
+    lcnt_unlock_list_entry(next);
+    lcnt_unlock_list_entry(prev);
 }
 
-void erts_lcnt_late_init() {
-    /* set start timer and zero statistics */
-    erts_lcnt_clear_counters();
-    erts_thr_install_exit_handler(erts_lcnt_thread_exit_handler);
-}
+static void lcnt_insert_list_carrier(erts_lcnt_lock_info_list_t *list,
+                                     erts_lcnt_lock_info_carrier_t *carrier) {
+    erts_lcnt_lock_info_t *next, *prev;
+    size_t i;
 
-/* list operations */
+    for(i = 0; i < carrier->entry_count; i++) {
+        erts_lcnt_lock_info_t *info = &carrier->entries[i];
 
-/* BEGIN ASSUMPTION: lcnt_data_lock taken */
+        info->prev = &carrier->entries[i - 1];
+        info->next = &carrier->entries[i + 1];
+    }
 
-erts_lcnt_lock_list_t *erts_lcnt_list_init(void) {
-    erts_lcnt_lock_list_t *list;
+    prev = &list->head;
 
-    list = (erts_lcnt_lock_list_t*)malloc(sizeof(erts_lcnt_lock_list_t));
-    if (!list) {
-        ERTS_INTERNAL_ERROR("Lock counter failed to allocate memory!");
-    }
-    list->head = NULL;
-    list->tail = NULL;
-    list->n    = 0;
-    return list;
-}
+    lcnt_lock_list_entry(prev);
 
-static void lcnt_list_free(erts_lcnt_lock_t *head) {
-    erts_lcnt_lock_t *lock, *next;
+    next = prev->next;
 
-    lock = head;
+    lcnt_lock_list_entry(next);
 
-    while(lock != NULL) {
-        next = lock->next;
-        free(lock);
-        lock = next;
-    }
+    next->prev = &carrier->entries[carrier->entry_count - 1];
+    carrier->entries[carrier->entry_count - 1].next = next;
+
+    prev->next = &carrier->entries[0];
+    carrier->entries[0].prev = prev;
+
+    lcnt_unlock_list_entry(next);
+    lcnt_unlock_list_entry(prev);
 }
 
-void erts_lcnt_list_insert(erts_lcnt_lock_list_t *list, erts_lcnt_lock_t *lock) {
-    erts_lcnt_lock_t *tail = NULL;
+static void lcnt_init_list(erts_lcnt_lock_info_list_t *list) {
+    /* Ensure that ref_count operations explode when touching the sentinels in
+     * DEBUG mode. */
+    ethr_atomic_init(&(list->head.ref_count), -1);
+    ethr_atomic_init(&(list->tail.ref_count), -1);
 
-    tail = list->tail;
-    if (tail) {
-        tail->next = lock;
-        lock->prev = tail;
-    } else {
-        list->head = lock;
-        lock->prev = NULL;
-        ASSERT(!lock->next);
-    }
-    lock->next = NULL;
-    list->tail = lock;
+    ethr_atomic32_init(&(list->head.lock), 0);
+    (list->head).next = &list->tail;
+    (list->head).prev = &list->tail;
 
-    list->n++;
+    ethr_atomic32_init(&(list->tail.lock), 0);
+    (list->tail).next = &list->head;
+    (list->tail).prev = &list->head;
 }
 
-void erts_lcnt_list_delete(erts_lcnt_lock_list_t *list, erts_lcnt_lock_t *lock) {
-    if (lock->next) lock->next->prev = lock->prev;
-    if (lock->prev) lock->prev->next = lock->next;
-    if (list->head == lock) list->head = lock->next;
-    if (list->tail == lock) list->tail = lock->prev;
+/* - Carrier operations - */
 
-    lock->prev = NULL;
-    lock->next = NULL;
-    list->n--;
+int lcnt_thr_progress_unmanaged_delay__(void) {
+    return erts_thr_progress_unmanaged_delay();
 }
-/* END ASSUMPTION: lcnt_data_lock taken */
 
+void lcnt_thr_progress_unmanaged_continue__(int handle) {
+    return erts_thr_progress_unmanaged_continue(handle);
+}
 
-/* lock operations */
+static void lcnt_deallocate_carrier_malloc(erts_lcnt_lock_info_carrier_t *carrier) {
+    ASSERT(ethr_atomic_read(&carrier->ref_count) == 0);
+    free(carrier);
+}
 
-/* interface to erl_threads.h */
-/* only lock on init and destroy, all others should use atomics */
-void erts_lcnt_init_lock(erts_lcnt_lock_t *lock, char *name, Uint16 flag ) {
-    erts_lcnt_init_lock_x(lock, name, flag, NIL);
+static void lcnt_deallocate_carrier_erts(erts_lcnt_lock_info_carrier_t *carrier) {
+    ASSERT(ethr_atomic_read(&carrier->ref_count) == 0);
+    erts_free(ERTS_ALC_T_LCNT_CARRIER, (void*)carrier);
 }
 
-void erts_lcnt_init_lock_x(erts_lcnt_lock_t *lock, char *name, Uint16 flag, Eterm id) {
-    int i;
+static void lcnt_thr_prg_cleanup_carrier(void *data) {
+    erts_lcnt_lock_info_carrier_t *carrier = data;
+    size_t entry_count, i;
 
-    if (flag & ERTS_LCNT_LT_DISABLE) {
-        ERTS_LCNT_CLEAR_FLAG(lock);
-        return;
+    /* carrier->entry_count will be replaced with garbage if it's deallocated
+     * on the final iteration, so we'll tuck it away to get a clean exit. */
+    entry_count = carrier->entry_count;
+
+    for(i = 0; i < entry_count; i++) {
+        ASSERT(ethr_atomic_read(&carrier->ref_count) >= (entry_count - i));
+
+        erts_lcnt_release_lock_info(&carrier->entries[i]);
     }
+}
 
-    lock->next = NULL;
-    lock->prev = NULL;
-    lock->flag = flag;
-    lock->name = name;
-    lock->id   = id;
+static void lcnt_schedule_carrier_cleanup(void *data) {
+    ErtsSchedulerData *esdp = erts_get_scheduler_data();
 
-    ethr_atomic_init(&lock->r_state, 0);
-    ethr_atomic_init(&lock->w_state, 0);
-#ifdef DEBUG
-    ethr_atomic_init(&lock->flowstate, 0);
-#endif
+    /* We can't issue cleanup jobs on anything other than normal schedulers, so
+     * we move to the first scheduler if required. */
+
+    if(!esdp || esdp->type != ERTS_SCHED_NORMAL) {
+        erts_schedule_misc_aux_work(1, &lcnt_schedule_carrier_cleanup, data);
+    } else {
+        erts_lcnt_lock_info_carrier_t *carrier = data;
+        size_t carrier_size;
 
-    lock->n_stats = 1;
+        carrier_size = sizeof(erts_lcnt_lock_info_carrier_t) +
+                       sizeof(erts_lcnt_lock_info_t) * carrier->entry_count;
 
-    for (i = 0; i < ERTS_LCNT_MAX_LOCK_LOCATIONS; i++) {
-        lcnt_clear_stats(&lock->stats[i]);
+        erts_schedule_thr_prgr_later_cleanup_op(&lcnt_thr_prg_cleanup_carrier,
+            data, (ErtsThrPrgrLaterOp*)&carrier->release_entries, carrier_size);
     }
+}
 
-    lcnt_lock();
-    erts_lcnt_list_insert(erts_lcnt_data->current_locks, lock);
-    lcnt_unlock();
+static void lcnt_info_deallocate(erts_lcnt_lock_info_t *info) {
+    lcnt_release_carrier__(info->carrier);
 }
 
-/* init empty, instead of zero struct
- * used by process locks probes
- */
-void erts_lcnt_init_lock_empty(erts_lcnt_lock_t *lock) {
-    lock->next = NULL;
-    lock->prev = NULL;
-    lock->flag = 0;
-    lock->name = NULL;
-    lock->id   = NIL;
-    ethr_atomic_init(&lock->r_state, 0);
-    ethr_atomic_init(&lock->w_state, 0);
-#ifdef DEBUG
-    ethr_atomic_init(&lock->flowstate, 0);
-#endif
-    lock->n_stats = 0;
-    sys_memzero(lock->stats, sizeof(lock->stats));
-}
-/* destroy lock */
-void erts_lcnt_destroy_lock(erts_lcnt_lock_t *lock) {
-    if (ERTS_LCNT_IS_LOCK_INVALID(lock)) return;
-    lcnt_lock();
-
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_COPYSAVE) {
-        erts_lcnt_lock_t *deleted_lock;
-        /* copy structure and insert the copy */
-        deleted_lock = (erts_lcnt_lock_t*)malloc(sizeof(erts_lcnt_lock_t));
-        if (!deleted_lock) {
-            ERTS_INTERNAL_ERROR("Lock counter failed to allocate memory!");
-        }
-        memcpy(deleted_lock, lock, sizeof(erts_lcnt_lock_t));
-        deleted_lock->next = NULL;
-        deleted_lock->prev = NULL;
-        erts_lcnt_list_insert(erts_lcnt_data->deleted_locks, deleted_lock);
-    }
-    /* delete original */
-    erts_lcnt_list_delete(erts_lcnt_data->current_locks, lock);
-    ERTS_LCNT_CLEAR_FLAG(lock);
+static void lcnt_info_dispose(erts_lcnt_lock_info_t *info) {
+    ASSERT(ethr_atomic_read(&info->ref_count) == 0);
 
-    lcnt_unlock();
+    if(erts_lcnt_rt_options & ERTS_LCNT_OPT_COPYSAVE) {
+        ethr_atomic_set(&info->ref_count, 1);
+
+        /* Move straight to deallocation the next time around. */
+        info->dispose = &lcnt_info_deallocate;
+
+        lcnt_insert_list_entry(&lcnt_deleted_lock_list, info);
+    } else {
+        lcnt_info_deallocate(info);
+    }
 }
 
-/* lock */
+static void lcnt_lock_info_init_helper(erts_lcnt_lock_info_t *info) {
+#ifdef DEBUG
+    ethr_atomic_init(&info->flowstate, 0);
+#endif
 
-void erts_lcnt_lock_opt(erts_lcnt_lock_t *lock, Uint16 option) {
-    erts_aint_t r_state = 0, w_state = 0;
-    erts_lcnt_thread_data_t *eltd;
+    ethr_atomic_init(&info->ref_count, 1);
+    ethr_atomic32_init(&info->lock, 0);
 
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_SUSPEND) return;
-    if (ERTS_LCNT_IS_LOCK_INVALID(lock)) return;
+    ethr_atomic_init(&info->r_state, 0);
+    ethr_atomic_init(&info->w_state, 0);
 
-    eltd = lcnt_get_thread_data();
-    ASSERT(eltd);
+    info->dispose = &lcnt_info_dispose;
 
-    w_state = ethr_atomic_read(&lock->w_state);
+    lcnt_clear_stats(info);
+}
 
-    if (option & ERTS_LCNT_LO_WRITE) {
-        r_state = ethr_atomic_read(&lock->r_state);
-        ethr_atomic_inc( &lock->w_state);
-    }
-    if (option & ERTS_LCNT_LO_READ) {
-        ethr_atomic_inc( &lock->r_state);
-    }
+erts_lcnt_lock_info_carrier_t *erts_lcnt_create_lock_info_carrier(int entry_count) {
+    erts_lcnt_lock_info_carrier_t *result;
+    size_t carrier_size, i;
+
+    ASSERT(entry_count > 0 && entry_count <= LCNT_MAX_CARRIER_ENTRIES);
 
-    /* we cannot acquire w_lock if either w or r are taken */
-    /* we cannot acquire r_lock if w_lock is taken */
+    carrier_size = sizeof(erts_lcnt_lock_info_carrier_t) +
+                   sizeof(erts_lcnt_lock_info_t) * entry_count;
 
-    if ((w_state > 0) || (r_state > 0)) {
-        eltd->lock_in_conflict = 1;
-        if (eltd->timer_set == 0) {
-            lcnt_time(&eltd->timer);
-        }
-        eltd->timer_set++;
+    if(lcnt_initialization_completed__) {
+        result = (erts_lcnt_lock_info_carrier_t*)erts_alloc(ERTS_ALC_T_LCNT_CARRIER, carrier_size);
+        result->deallocate = &lcnt_deallocate_carrier_erts;
     } else {
-        eltd->lock_in_conflict = 0;
+        result = (erts_lcnt_lock_info_carrier_t*)malloc(carrier_size);
+        result->deallocate = &lcnt_deallocate_carrier_malloc;
     }
-}
 
-void erts_lcnt_lock(erts_lcnt_lock_t *lock) {
-    erts_aint_t w_state;
-    erts_lcnt_thread_data_t *eltd;
+    ethr_atomic_init(&result->ref_count, entry_count);
 
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_SUSPEND) return;
-    if (ERTS_LCNT_IS_LOCK_INVALID(lock)) return;
+    result->entry_count = entry_count;
 
-    w_state = ethr_atomic_read(&lock->w_state);
-    ethr_atomic_inc(&lock->w_state);
-    eltd = lcnt_get_thread_data();
+    for(i = 0; i < entry_count; i++) {
+        erts_lcnt_lock_info_t *info = &result->entries[i];
 
-    ASSERT(eltd);
+        lcnt_lock_info_init_helper(info);
 
-    if (w_state > 0) {
-        eltd->lock_in_conflict = 1;
-        /* only set the timer if nobody else has it
-         * This should only happen when proc_locks aquires several locks
-         * 'atomicly'. All other locks will block the thread if w_state > 0
-         * i.e. locked.
-         */
-        if (eltd->timer_set == 0) {
-            lcnt_time(&eltd->timer);
-        }
-        eltd->timer_set++;
-    } else {
-        eltd->lock_in_conflict = 0;
+        info->carrier = result;
     }
-}
-
-/* if a lock wasn't really a lock operation, bad bad process locks */
-
-void erts_lcnt_lock_unaquire(erts_lcnt_lock_t *lock) {
-    /* should check if this thread was "waiting" */
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_SUSPEND) return;
-    if (ERTS_LCNT_IS_LOCK_INVALID(lock)) return;
 
-    ethr_atomic_dec(&lock->w_state);
+    return result;
 }
 
-/*
- * erts_lcnt_lock_post
- *
- * Used when we get a lock (i.e. directly after a lock operation)
- * if the timer was set then we had to wait for the lock
- * lock_post will calculate the wait time.
- */
+void erts_lcnt_install(erts_lcnt_ref_t *ref, erts_lcnt_lock_info_carrier_t *carrier) {
+    ethr_sint_t swapped_carrier;
 
-void erts_lcnt_lock_post(erts_lcnt_lock_t *lock) {
-    erts_lcnt_lock_post_x(lock, (char*)str_undefined, 0);
-}
+    swapped_carrier = ethr_atomic_cmpxchg_mb(ref, (ethr_sint_t)carrier, (ethr_sint_t)NULL);
 
-void erts_lcnt_lock_post_x(erts_lcnt_lock_t *lock, char *file, unsigned int line) {
-    erts_lcnt_thread_data_t *eltd;
-    erts_lcnt_time_t timer;
-    erts_lcnt_time_t time_wait;
-    erts_lcnt_lock_stats_t *stats;
+    if(swapped_carrier != (ethr_sint_t)NULL) {
 #ifdef DEBUG
-    erts_aint_t flowstate;
+        ASSERT(ethr_atomic_read(&carrier->ref_count) == carrier->entry_count);
+        ethr_atomic_set(&carrier->ref_count, 0);
 #endif
 
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_SUSPEND) return;
-    if (ERTS_LCNT_IS_LOCK_INVALID(lock)) return;
+        carrier->deallocate(carrier);
+    } else {
+        lcnt_insert_list_carrier(&lcnt_current_lock_list, carrier);
+    }
+}
+
+void erts_lcnt_uninstall(erts_lcnt_ref_t *ref) {
+    ethr_sint_t previous_carrier, swapped_carrier;
 
-#ifdef DEBUG
-    if (!(lock->flag & (ERTS_LCNT_LT_RWMUTEX | ERTS_LCNT_LT_RWSPINLOCK))) {
-        flowstate = ethr_atomic_read(&lock->flowstate);
-        ASSERT(flowstate == 0);
-        ethr_atomic_inc(&lock->flowstate);
+    previous_carrier = ethr_atomic_read(ref);
+    swapped_carrier = ethr_atomic_cmpxchg_mb(ref, (ethr_sint_t)NULL, previous_carrier);
+
+    if(previous_carrier && previous_carrier == swapped_carrier) {
+        lcnt_schedule_carrier_cleanup((void*)previous_carrier);
     }
-#endif
+}
 
-    eltd = lcnt_get_thread_data();
+/* - Initialization - */
 
-    ASSERT(eltd);
+void erts_lcnt_pre_thr_init() {
+    /* Ensure that the dependency hack mentioned in the header doesn't
+     * explode at runtime. */
+    ERTS_CT_ASSERT(sizeof(LcntThrPrgrLaterOp) >= sizeof(ErtsThrPrgrLaterOp));
+    ERTS_CT_ASSERT(ERTS_THR_PRGR_DHANDLE_MANAGED == 
+        (ErtsThrPrgrDelayHandle)LCNT_THR_PRGR_DHANDLE_MANAGED);
 
-    /* if lock was in conflict, time it */
-    stats = lcnt_get_lock_stats(lock, file, line);
-    if (eltd->timer_set) {
-        lcnt_time(&timer);
+    lcnt_init_list(&lcnt_current_lock_list);
+    lcnt_init_list(&lcnt_deleted_lock_list);
+}
 
-        lcnt_time_diff(&time_wait, &timer, &(eltd->timer));
-        lcnt_update_stats(stats, eltd->lock_in_conflict, &time_wait);
-        eltd->timer_set--;
-        ASSERT(eltd->timer_set >= 0);
-    } else {
-        lcnt_update_stats(stats, eltd->lock_in_conflict, NULL);
-    }
+void erts_lcnt_post_thr_init() {
+    /* ASSUMPTION: this is safe since it runs prior to the creation of other
+     * threads (Directly after ethread init). */
 
+    ethr_tsd_key_create(&lcnt_thr_data_key__, "lcnt_data");
+
+    erts_lcnt_thread_setup();
 }
 
-/* unlock */
+void erts_lcnt_late_init() {
+    /* Set start timer and zero all statistics */
+    erts_lcnt_clear_counters();
+    erts_thr_install_exit_handler(erts_lcnt_thread_exit_handler);
 
-void erts_lcnt_unlock_opt(erts_lcnt_lock_t *lock, Uint16 option) {
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_SUSPEND) return;
-    if (ERTS_LCNT_IS_LOCK_INVALID(lock)) return;
-    if (option & ERTS_LCNT_LO_WRITE) ethr_atomic_dec(&lock->w_state);
-    if (option & ERTS_LCNT_LO_READ ) ethr_atomic_dec(&lock->r_state);
+    /* It's safe to use erts_alloc and thread progress past this point. */
+    lcnt_initialization_completed__ = 1;
 }
 
-void erts_lcnt_unlock(erts_lcnt_lock_t *lock) {
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_SUSPEND) return;
-    if (ERTS_LCNT_IS_LOCK_INVALID(lock)) return;
-#ifdef DEBUG
-    {
-        erts_aint_t w_state;
-        erts_aint_t flowstate;
-
-        /* flowstate */
-        flowstate = ethr_atomic_read(&lock->flowstate);
-        ASSERT(flowstate == 1);
-        ethr_atomic_dec(&lock->flowstate);
-
-        /* write state */
-        w_state = ethr_atomic_read(&lock->w_state);
-        ASSERT(w_state > 0);
-    }
-#endif
-    ethr_atomic_dec(&lock->w_state);
+void erts_lcnt_thread_setup() {
+    lcnt_thread_data_t__ *eltd = lcnt_thread_data_alloc();
+
+    ASSERT(eltd);
+
+    ethr_tsd_set(lcnt_thr_data_key__, eltd);
 }
 
-/* trylock */
+void erts_lcnt_thread_exit_handler() {
+    lcnt_thread_data_t__ *eltd = lcnt_get_thread_data__();
 
-void erts_lcnt_trylock_opt(erts_lcnt_lock_t *lock, int res, Uint16 option) {
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_SUSPEND) return;
-    if (ERTS_LCNT_IS_LOCK_INVALID(lock)) return;
-    /* Determine lock_state via res instead of state */
-    if (res != EBUSY) {
-        if (option & ERTS_LCNT_LO_WRITE) ethr_atomic_inc(&lock->w_state);
-        if (option & ERTS_LCNT_LO_READ ) ethr_atomic_inc(&lock->r_state);
-        lcnt_update_stats(&(lock->stats[0]), 0, NULL);
-    } else {
-        ethr_atomic_inc(&lock->stats[0].tries);
-        ethr_atomic_inc(&lock->stats[0].colls);
+    if (eltd) {
+        free(eltd);
     }
 }
 
+/* - BIF interface - */
 
-void erts_lcnt_trylock(erts_lcnt_lock_t *lock, int res) {
-    /* Determine lock_state via res instead of state */
-    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_SUSPEND) return;
-    if (ERTS_LCNT_IS_LOCK_INVALID(lock)) return;
-    if (res != EBUSY) {
+void erts_lcnt_retain_lock_info(erts_lcnt_lock_info_t *info) {
 #ifdef DEBUG
-        {
-            erts_aint_t flowstate;
-            flowstate = ethr_atomic_read(&lock->flowstate);
-            ASSERT(flowstate == 0);
-            ethr_atomic_inc( &lock->flowstate);
-        }
+    ASSERT(ethr_atomic_inc_read_acqb(&info->ref_count) >= 2);
+#else
+    ethr_atomic_inc_acqb(&info->ref_count);
 #endif
-        ethr_atomic_inc(&lock->w_state);
-        lcnt_update_stats(&(lock->stats[0]), 0, NULL);
-    } else {
-        ethr_atomic_inc(&lock->stats[0].tries);
-        ethr_atomic_inc(&lock->stats[0].colls);
-    }
 }
 
-/* thread operations */
+void erts_lcnt_release_lock_info(erts_lcnt_lock_info_t *info) {
+    ethr_sint_t count;
 
-void erts_lcnt_thread_setup(void) {
-    erts_lcnt_thread_data_t *eltd;
+    /* We need to acquire the lock before decrementing ref_count to avoid
+     * racing with list iteration; there's a short window between reading the
+     * reference to info and increasing its ref_count. */
+    lcnt_lock_list_entry_with_neighbors(info);
 
-    lcnt_lock();
-    /* lock for thread id global update */
-    eltd = lcnt_thread_data_alloc();
-    lcnt_unlock();
-    ASSERT(eltd);
-    ethr_tsd_set(lcnt_thr_data_key, eltd);
-}
+    count = ethr_atomic_dec_read(&info->ref_count);
 
-void erts_lcnt_thread_exit_handler() {
-    erts_lcnt_thread_data_t *eltd;
+    ASSERT(count >= 0);
 
-    eltd = ethr_tsd_get(lcnt_thr_data_key);
+    if(count > 0) {
+        lcnt_unlock_list_entry_with_neighbors(info);
+    } else {
+        (info->next)->prev = info->prev;
+        (info->prev)->next = info->next;
 
-    if (eltd) {
-        free(eltd);
+        lcnt_unlock_list_entry_with_neighbors(info);
+
+        info->dispose(info);
     }
 }
 
-/* bindings for bifs */
-
 Uint16 erts_lcnt_set_rt_opt(Uint16 opt) {
     Uint16 prev;
     prev = (erts_lcnt_rt_options & opt);
@@ -656,51 +507,72 @@ Uint16 erts_lcnt_clear_rt_opt(Uint16 opt) {
 }
 
 void erts_lcnt_clear_counters(void) {
-    erts_lcnt_lock_t *lock;
-    erts_lcnt_lock_list_t *list;
-    erts_lcnt_lock_stats_t *stats;
-    int i;
+    erts_lcnt_lock_info_t *iterator;
 
-    lcnt_lock();
+    lcnt_time__(&lcnt_timer_start);
 
-    list = erts_lcnt_data->current_locks;
+    iterator = NULL;
+    while(erts_lcnt_iterate_list(&lcnt_current_lock_list, &iterator)) {
+        lcnt_clear_stats(iterator);
+    }
 
-    for (lock = list->head; lock != NULL; lock = lock->next) {
-        for( i = 0; i < ERTS_LCNT_MAX_LOCK_LOCATIONS; i++) {
-            stats = &lock->stats[i];
-            lcnt_clear_stats(stats);
-        }
-        lock->n_stats = 1;
+    iterator = NULL;
+    while(erts_lcnt_iterate_list(&lcnt_deleted_lock_list, &iterator)) {
+        erts_lcnt_release_lock_info(iterator);
     }
+}
+
+erts_lcnt_data_t erts_lcnt_get_data(void) {
+    erts_lcnt_time_t timer_stop;
+    erts_lcnt_data_t result;
 
-    lock = erts_lcnt_data->deleted_locks->head;
-    erts_lcnt_data->deleted_locks->head = NULL;
-    erts_lcnt_data->deleted_locks->tail = NULL;
-    erts_lcnt_data->deleted_locks->n = 0;
+    lcnt_time__(&timer_stop);
 
-    lcnt_time(&timer_start);
+    result.timer_start = lcnt_timer_start;
 
-    lcnt_unlock();
+    result.current_locks = &lcnt_current_lock_list;
+    result.deleted_locks = &lcnt_deleted_lock_list;
 
-    /* free deleted locks */
-    lcnt_list_free(lock);
+    lcnt_time_diff__(&result.duration, &timer_stop, &result.timer_start);
+
+    return result;
 }
 
-erts_lcnt_data_t *erts_lcnt_get_data(void) {
-    erts_lcnt_time_t timer_stop;
+const char *erts_lcnt_lock_type(Uint16 type) {
+    switch(type & ERTS_LCNT_LT_ALL) {
+        case ERTS_LCNT_LT_SPINLOCK:   return "spinlock";
+        case ERTS_LCNT_LT_RWSPINLOCK: return "rw_spinlock";
+        case ERTS_LCNT_LT_MUTEX:      return "mutex";
+        case ERTS_LCNT_LT_RWMUTEX:    return "rw_mutex";
+        case ERTS_LCNT_LT_PROCLOCK:   return "proclock";
+        default:                      return "";
+    }
+}
 
-    lcnt_lock();
+int erts_lcnt_iterate_list(erts_lcnt_lock_info_list_t *list, erts_lcnt_lock_info_t **iterator) {
+    erts_lcnt_lock_info_t *current, *next;
 
-    lcnt_time(&timer_stop);
-    lcnt_time_diff(&(erts_lcnt_data->duration), &timer_stop, &timer_start);
+    current = *iterator ? *iterator : &list->head;
 
-    lcnt_unlock();
+    ASSERT(current != &list->tail);
 
-    return erts_lcnt_data;
-}
+    lcnt_lock_list_entry(current);
+
+    next = current->next;
+
+    if(next != &list->tail) {
+        erts_lcnt_retain_lock_info(next);
+    }
+
+    lcnt_unlock_list_entry(current);
+
+    if(current != &list->head) {
+        erts_lcnt_release_lock_info(current);
+    }
+
+    *iterator = next;
 
-char *erts_lcnt_lock_type(Uint16 type) {
-    return lcnt_lock_type(type);
+    return next != &list->tail;
 }
 
-#endif /* ifdef ERTS_ENABLE_LOCK_COUNT */
+#endif /* #ifdef ERTS_ENABLE_LOCK_COUNT */
diff --git a/erts/emulator/beam/erl_lock_count.h b/erts/emulator/beam/erl_lock_count.h
index 6caffbfe86..c89dfcba47 100644
--- a/erts/emulator/beam/erl_lock_count.h
+++ b/erts/emulator/beam/erl_lock_count.h
@@ -18,60 +18,56 @@
  * %CopyrightEnd%
  */
 
-/*
- * Description:	Statistics for locks.
- *
- * Author:	Björn-Egil Dahlberg
- * Date:	2008-07-03
- * Abstract:
- * 	Locks statistics internal representation.
- * 	
- * 	Conceptual representation, 
- * 	- set name
- * 	| - id (the unique lock)
- * 	| | - lock type
- * 	| | - statistics
- * 	| | | - location (file and line number)
- * 	| | | - tries
- * 	| | | - collisions (including trylock busy)
- * 	| | | - timer (time spent in waiting for lock)
- * 	| | | - n_timer (collisions excluding trylock busy)
- * 	| | | - histogram
- * 	| | | | - # 0 = log2(lock wait_time ns)
- * 	| | | | - ...
- * 	| | | | - # n = log2(lock wait_time ns)
- *
- * 	Each instance of a lock is the unique lock, i.e. set and id in that set.
- * 	For each lock there is a set of statistics with where and what impact
- * 	the lock aqusition had.
- *
- * 	Runtime options
- * 	- suspend, used when internal lock-counting can't be applied. For instance
- * 	  when allocating a term for the outside and halloc needs to be used.
- * 	  Default: off.
- * 	- location, reserved and not used.
- * 	- proclock, disable proclock counting. Used when performance might be an
- * 	  issue. Accessible from erts_debug:lock_counters({process_locks, bool()}).
- * 	  Default: off.
- * 	- copysave, enable saving of destroyed locks (and thereby its statistics).
- * 	  If memory constraints is an issue this need to be disabled.
- * 	  Accessible from erts_debug:lock_counters({copy_save, bool()}).
- * 	  Default: off.
+/**
+ * @description Statistics for locks.
+ * @file erl_lock_count.h
+ *
+ * @author Björn-Egil Dahlberg
+ * @author John Högberg
+ *
+ * Conceptual representation:
  *
+ *     - set name
+ *     | - id (the unique lock)
+ *     | | - lock type
+ *     | | - statistics
+ *     | | | - location (file and line number)
+ *     | | | - attempts
+ *     | | | - collisions (including trylock busy)
+ *     | | | - timer (time spent in waiting for lock)
+ *     | | | - n_timer (collisions excluding trylock busy)
+ *     | | | - histogram
+ *     | | | | - # 0 = log2(lock wait_time ns)
+ *     | | | | - ...
+ *     | | | | - # n = log2(lock wait_time ns)
+ *
+ * Each instance of a lock is the unique lock, i.e. set and id in that set.
+ * For each lock there is a set of statistics with where and what impact
+ * the lock aqusition had.
+ *
+ * Runtime options:
+ * - location, reserved and not used.
+ * - proclock, disable proclock counting. Used when performance might be an
+ *   issue. Accessible from erts_debug:lock_counters({process_locks, bool()}).
+ *   Default: off.
+ * - copysave, enable saving of destroyed locks (and thereby its statistics).
+ *   If memory constraints is an issue this need to be disabled.
+ *   Accessible from erts_debug:lock_counters({copy_save, bool()}).
+ *   Default: off.
  */
 
-#include "sys.h"
-
 #ifndef ERTS_LOCK_COUNT_H__
 #define ERTS_LOCK_COUNT_H__
 
 #ifdef  ERTS_ENABLE_LOCK_COUNT
 #ifndef ERTS_ENABLE_LOCK_POSITION
-/* Enable in order for _x variants of mtx functions to be used. */
+/** @brief Controls whether _x variants of mtx functions are used. */
 #define ERTS_ENABLE_LOCK_POSITION 1
 #endif
 
+#include "sys.h"
 #include "ethread.h"
+#include "erl_term.h"
 
 #define ERTS_LCNT_MAX_LOCK_LOCATIONS  (10)
 
@@ -106,13 +102,8 @@
                                 | ERTS_LCNT_LT_RWMUTEX    \
                                 | ERTS_LCNT_LT_PROCLOCK   )
 
-#define ERTS_LCNT_LOCK_TYPE(lock)       ((lock)->flag & ERTS_LCNT_LT_ALL)
-#define ERTS_LCNT_IS_LOCK_INVALID(lock) (!((lock)->flag & ERTS_LCNT_LT_ALL))
-#define ERTS_LCNT_CLEAR_FLAG(lock)      ((lock)->flag = 0)
-
-/* runtime options */
+/* Runtime options */
 
-#define ERTS_LCNT_OPT_SUSPEND  (((Uint16) 1) << 0)
 #define ERTS_LCNT_OPT_LOCATION (((Uint16) 1) << 1)
 #define ERTS_LCNT_OPT_PROCLOCK (((Uint16) 1) << 2)
 #define ERTS_LCNT_OPT_PORTLOCK (((Uint16) 1) << 3)
@@ -123,116 +114,818 @@ typedef struct {
     unsigned long ns;
 } erts_lcnt_time_t;
 
-extern erts_lcnt_time_t timer_start;
-
 typedef struct {
-    Uint32 ns[ERTS_LCNT_HISTOGRAM_SLOT_SIZE]; /* log2 array of nano seconds occurences */
+    /* @brief log2 array of nano seconds occurences */
+    Uint32 ns[ERTS_LCNT_HISTOGRAM_SLOT_SIZE];
 } erts_lcnt_hist_t;
 
-typedef struct erts_lcnt_lock_stats_s {
-    /* "tries" and "colls" needs to be atomic since
-     * trylock busy does not acquire a lock and there
-     * is no post action to rectify the situation
-     */
+typedef struct {
+    /** @brief In which file the lock was taken. May be NULL. */
+    const char *file;
+    /** @brief Line number in \c file */
+    unsigned int line;
+
+    /* "attempts" and "collisions" need to be atomic since try_lock busy does
+     * not acquire a lock and there is no post action to rectify the
+     * situation. */
 
-    char         *file;       /* which file the lock was taken */
-    unsigned int  line;       /* line number in file */
+    ethr_atomic_t attempts;
+    ethr_atomic_t collisions;
 
-    ethr_atomic_t tries;      /* n tries to get lock */
-    ethr_atomic_t colls;      /* n collisions of tries to get lock */
+    erts_lcnt_time_t total_time_waited;
+    Uint64 times_waited;
 
-    unsigned long timer_n;    /* #times waited for lock */
-    erts_lcnt_time_t timer;   /* total wait time for lock */
-    erts_lcnt_hist_t hist;
+    erts_lcnt_hist_t wait_time_histogram;
 } erts_lcnt_lock_stats_t;
 
-/* rw locks uses both states, other locks only uses w_state */
-typedef struct erts_lcnt_lock_s {
-    char *name;            /* lock name */
-    Uint16 flag;           /* lock type */
-    Eterm id;              /* id if possible */
+typedef struct lcnt_lock_info_t_ {
+    const char *name; /**< Lock name */
+    Uint16 flag;      /**< Lock type */
+    Eterm id;         /**< Id if possible, must be an immediate */
 
-#ifdef DEBUG
+    /* The first entry is reserved as a fallback for when location information
+     * is missing, and when the lock is used in more than (MAX_LOCK_LOCATIONS
+     * - 1) different places. */
+    erts_lcnt_lock_stats_t location_stats[ERTS_LCNT_MAX_LOCK_LOCATIONS];
+    unsigned int location_count;
+
+    /* -- Everything below is internal to this module ---------------------- */
+
+    /* Lock states; rw locks uses both states, other locks only uses w_state */
+
+    /** @brief Write state. 0 = not taken, otherwise n threads waiting */
+    ethr_atomic_t w_state;
+    /** @brief Read state. 0 = not taken, > 0 -> writes will wait */
+    ethr_atomic_t r_state;
+
+#ifdef LCNT_DEBUG_LOCK_FLOW
+    /** @brief Tracks lock/unlock operations. This will explode if the lock is
+     * held at the time lock counting is installed.
+     *
+     * Avoid enabling existing locks at runtime while running in this
+     * configuration. */
     ethr_atomic_t flowstate;
 #endif
 
-    /* lock states */
-    ethr_atomic_t w_state; /* 0 not taken, otherwise n threads waiting */
-    ethr_atomic_t r_state; /* 0 not taken, > 0 -> writes will wait */
+    struct lcnt_lock_info_t_ *prev;
+    struct lcnt_lock_info_t_ *next;
 
-    /* statistics */
-    unsigned int n_stats;
-    erts_lcnt_lock_stats_t stats[ERTS_LCNT_MAX_LOCK_LOCATIONS]; /* first entry is "undefined"*/
+    /** @brief Used in place of erts_refc_t to avoid a circular dependency. */
+    ethr_atomic_t ref_count;
+    ethr_atomic32_t lock;
 
-    /* chains for list handling  */
-    /* data is hold by lcnt_lock */
-    struct erts_lcnt_lock_s *prev;
-    struct erts_lcnt_lock_s *next;
-} erts_lcnt_lock_t;
+    /** @brief Deletion hook called once \c ref_count reaches 0; may defer
+     * deletion by modifying \c ref_count. */
+    void (*dispose)(struct lcnt_lock_info_t_ *);
 
-typedef struct {
-    erts_lcnt_lock_t *head;
-    erts_lcnt_lock_t *tail;
-    unsigned long n;
-} erts_lcnt_lock_list_t;
+    struct lcnt_lock_info_carrier_ *carrier;
+} erts_lcnt_lock_info_t;
+
+typedef struct lcnt_lock_info_list_ {
+    erts_lcnt_lock_info_t head;
+    erts_lcnt_lock_info_t tail;
+} erts_lcnt_lock_info_list_t;
 
 typedef struct {
-    erts_lcnt_time_t duration;			/* time since last clear */
-    erts_lcnt_lock_list_t *current_locks;
-    erts_lcnt_lock_list_t *deleted_locks;
+    erts_lcnt_time_t timer_start; /**< Time of last clear */
+    erts_lcnt_time_t duration; /**< Time since last clear */
+
+    erts_lcnt_lock_info_list_t *current_locks;
+    erts_lcnt_lock_info_list_t *deleted_locks;
 } erts_lcnt_data_t;
 
-typedef struct {
-    int id;
+typedef struct lcnt_lock_info_carrier_ erts_lcnt_lock_info_carrier_t;
 
-    erts_lcnt_time_t timer;	/* timer         */
-    int timer_set;		/* bool          */
-    int lock_in_conflict;       /* bool          */
-} erts_lcnt_thread_data_t;
+typedef ethr_atomic_t erts_lcnt_ref_t;
 
-/* globals */
+/* -- Globals -------------------------------------------------------------- */
 
 extern Uint16 erts_lcnt_rt_options;
 
-/* function declerations */
-
-void erts_lcnt_init(void);
+/* -- Lock operations ------------------------------------------------------
+ *
+ * All of these will nop if there's nothing "installed" on the given reference,
+ * in order to transparently support enable/disable at runtime. */
+
+/** @brief Records that a lock is being acquired. */
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock(erts_lcnt_ref_t *ref);
+
+/** @copydoc erts_lcnt_lock
+ * @param option Notes whether the lock is a read or write lock. */
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock_opt(erts_lcnt_ref_t *ref, Uint16 option);
+
+/** @brief Records that a lock has been acquired. */
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock_post(erts_lcnt_ref_t *ref);
+
+/** @copydoc erts_lcnt_lock_post.
+ * @param file The name of the file where the lock was acquired.
+ * @param line The line at which the lock was acquired. */
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock_post_x(erts_lcnt_ref_t *ref, char *file, unsigned int line);
+
+/** @brief Records that a lock has been released. */
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_unlock(erts_lcnt_ref_t *ref);
+
+/** @copydoc erts_lcnt_unlock_opt
+ * @param option Whether the lock is a read or write lock. */
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_unlock_opt(erts_lcnt_ref_t *ref, Uint16 option);
+
+/** @brief Rectifies the case where a lock wasn't actually a lock operation.
+ *
+ * Only used for process locks at the moment. */
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock_unacquire(erts_lcnt_ref_t *ref);
+
+/** @brief Records the result of a trylock, placing the queried lock status in
+ * \c result. */
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_trylock(erts_lcnt_ref_t *ref, int result);
+
+/** @copydoc erts_lcnt_trylock
+ * @param option Whether the lock is a read or write lock. */
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_trylock_opt(erts_lcnt_ref_t *ref, int result, Uint16 option);
+
+/* Indexed variants of the standard lock operations, for use when a single
+ * reference contains many counters (eg. process locks).
+ *
+ * erts_lcnt_open_ref must be used to safely extract the installed carrier,
+ * which must released with erts_lcnt_close_reference on success.
+ *
+ * Refer to \c erts_lcnt_lock for example usage. */
+
+ERTS_GLB_FORCE_INLINE
+int erts_lcnt_open_ref(erts_lcnt_ref_t *ref, int *handle, erts_lcnt_lock_info_carrier_t **result);
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_close_ref(int handle, erts_lcnt_lock_info_carrier_t *carrier);
+
+ERTS_GLB_INLINE
+void erts_lcnt_lock_idx(erts_lcnt_lock_info_carrier_t *carrier, int index);
+ERTS_GLB_INLINE
+void erts_lcnt_lock_opt_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, Uint16 option);
+
+ERTS_GLB_INLINE
+void erts_lcnt_lock_post_idx(erts_lcnt_lock_info_carrier_t *carrier, int index);
+ERTS_GLB_INLINE
+void erts_lcnt_lock_post_x_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, char *file, unsigned int line);
+
+ERTS_GLB_INLINE
+void erts_lcnt_lock_unacquire_idx(erts_lcnt_lock_info_carrier_t *carrier, int index);
+
+ERTS_GLB_INLINE
+void erts_lcnt_unlock_idx(erts_lcnt_lock_info_carrier_t *carrier, int index);
+ERTS_GLB_INLINE
+void erts_lcnt_unlock_opt_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, Uint16 option);
+
+ERTS_GLB_INLINE
+void erts_lcnt_trylock_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, int result);
+ERTS_GLB_INLINE
+void erts_lcnt_trylock_opt_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, int result, Uint16 option);
+
+/* -- Reference operations ------------------------------------------------- */
+
+erts_lcnt_lock_info_carrier_t *erts_lcnt_create_lock_info_carrier(int count);
+
+/** @brief Fills in the name and lock type of the given index. */
+#define erts_lcnt_init_lock_info_idx(carrier, index, name, flag) \
+    erts_lcnt_init_lock_info_x_idx(carrier, index, name, flag, NIL)
+
+/** @copydoc erts_lcnt_install_new_lock_info
+ * @param id An immediate erlang term with whatever extra data you want to
+ * identify this lock with. */
+ERTS_GLB_INLINE
+void erts_lcnt_init_lock_info_x_idx(erts_lcnt_lock_info_carrier_t *carrier, int index,
+    const char *name, Uint16 flag, Eterm id);
+
+/** @brief Initializes a lock counter reference; this must be called prior to
+ * using any other functions in this module. */
+#define erts_lcnt_init_ref(ref) ethr_atomic_init(ref, (ethr_sint_t)NULL);
+
+/** @brief Atomically installs the given lock counters. Nops (and releases the
+ * provided carrier) if something was already installed. */
+void erts_lcnt_install(erts_lcnt_ref_t *ref, erts_lcnt_lock_info_carrier_t *carrier);
+
+/** @brief Atomically removes the currently installed lock counters. Nops if
+ * nothing was installed. */
+void erts_lcnt_uninstall(erts_lcnt_ref_t *ref);
+
+/** @brief Convenience macro to install a single lock counter of the given
+ * name and type. */
+#define erts_lcnt_install_new_lock_info(reference, name, flag) \
+    erts_lcnt_install_new_lock_info_x(reference, name, flag, NIL)
+
+/** @copydoc erts_lcnt_install_new_lock_info
+ * @param id An immediate erlang term with whatever extra data you want to
+ * identify this lock with. */
+#define erts_lcnt_install_new_lock_info_x(reference, name, flag, id) \
+    do { \
+        erts_lcnt_lock_info_carrier_t *__carrier; \
+        __carrier = erts_lcnt_create_lock_info_carrier(1); \
+        erts_lcnt_init_lock_info_x_idx(__carrier, 0, name, flag, id); \
+        erts_lcnt_install(reference, __carrier); \
+    } while(0)
+
+/* -- Module initialization ------------------------------------------------ */
+
+void erts_lcnt_pre_thr_init(void);
+void erts_lcnt_post_thr_init(void);
 void erts_lcnt_late_init(void);
 
-/* thread operations */
 void erts_lcnt_thread_setup(void);
 void erts_lcnt_thread_exit_handler(void);
 
-/* list operations (local)  */
-erts_lcnt_lock_list_t *erts_lcnt_list_init(void);
+/* -- BIF interface -------------------------------------------------------- */
 
-void erts_lcnt_list_insert(erts_lcnt_lock_list_t *list, erts_lcnt_lock_t *lock);
-void erts_lcnt_list_delete(erts_lcnt_lock_list_t *list, erts_lcnt_lock_t *lock);
-
-/* lock operations (global) */
-void erts_lcnt_init_lock(erts_lcnt_lock_t *lock, char *name, Uint16 flag);
-void erts_lcnt_init_lock_x(erts_lcnt_lock_t *lock, char *name, Uint16 flag, Eterm id);
-void erts_lcnt_init_lock_empty(erts_lcnt_lock_t *lock);
-void erts_lcnt_destroy_lock(erts_lcnt_lock_t *lock);
+/** @brief Safely iterates through all entries in the given list.
+ *
+ * The referenced item will be valid until the next call to
+ * \c erts_lcnt_iterate_list after which point it may be destroyed; call
+ * erts_lcnt_retain_lock_info if you wish to hang on to it beyond that point.
+ *
+ * Iteration can be cancelled by calling erts_lcnt_release_lock_info on the
+ * iterator and breaking out of the loop.
+ *
+ * @param iterator The iteration variable; set the pointee to NULL to start
+ * iteration.
+ * @return 1 while the iterator is valid, 0 at the end of the list. */
+int erts_lcnt_iterate_list(erts_lcnt_lock_info_list_t *list, erts_lcnt_lock_info_t **iterator);
 
-void erts_lcnt_lock(erts_lcnt_lock_t *lock);
-void erts_lcnt_lock_opt(erts_lcnt_lock_t *lock, Uint16 option);
-void erts_lcnt_lock_post(erts_lcnt_lock_t *lock);
-void erts_lcnt_lock_post_x(erts_lcnt_lock_t *lock, char *file, unsigned int line);
-void erts_lcnt_lock_unaquire(erts_lcnt_lock_t *lock);
+/** @brief Clears the counter state of all locks, and releases all locks
+ * preserved through ERTS_LCNT_OPT_COPYSAVE (if any). */
+void erts_lcnt_clear_counters(void);
 
-void erts_lcnt_unlock(erts_lcnt_lock_t *lock);
-void erts_lcnt_unlock_opt(erts_lcnt_lock_t *lock, Uint16 option);
+/** @brief Retrieves the global lock counter state.
+ *
+ * Note that the lists may be modified while you're mucking around with them.
+ * Always use \c erts_lcnt_iterate_list to enumerate them. */
+erts_lcnt_data_t erts_lcnt_get_data(void);
 
-void erts_lcnt_trylock_opt(erts_lcnt_lock_t *lock, int res, Uint16 option);
-void erts_lcnt_trylock(erts_lcnt_lock_t *lock, int res);
+void erts_lcnt_retain_lock_info(erts_lcnt_lock_info_t *info);
+void erts_lcnt_release_lock_info(erts_lcnt_lock_info_t *info);
 
-/* bif interface */
 Uint16 erts_lcnt_set_rt_opt(Uint16 opt);
 Uint16 erts_lcnt_clear_rt_opt(Uint16 opt);
-void   erts_lcnt_clear_counters(void);
-char  *erts_lcnt_lock_type(Uint16 type);
-erts_lcnt_data_t *erts_lcnt_get_data(void);
+
+const char *erts_lcnt_lock_type(Uint16 type);
+
+/* -- Inline implementation ------------------------------------------------ */
+
+/* The following is a hack to get the things we need from erl_thr_progress.h,
+ * which we can't #include without dependency hell breaking loose.
+ *
+ * The size of LcntThrPrgrLaterOp and value of the constant are verified at
+ * compile-time in erts_lcnt_pre_thr_init. */
+
+int lcnt_thr_progress_unmanaged_delay__(void);
+void lcnt_thr_progress_unmanaged_continue__(int handle);
+typedef struct { Uint64 _[4]; } LcntThrPrgrLaterOp;
+#define LCNT_THR_PRGR_DHANDLE_MANAGED -1
+
+struct lcnt_lock_info_carrier_ {
+    ethr_atomic_t ref_count;
+
+    void (*deallocate)(struct lcnt_lock_info_carrier_ *);
+
+    LcntThrPrgrLaterOp release_entries;
+
+    unsigned char entry_count;
+    erts_lcnt_lock_info_t entries[];
+};
+
+typedef struct {
+    erts_lcnt_time_t timer; /* timer */
+    int timer_set;          /* bool */
+    int lock_in_conflict;   /* bool */
+} lcnt_thread_data_t__;
+
+extern ethr_tsd_key lcnt_thr_data_key__;
+
+/** @brief Some operations (eg erts_alloc or erts_thr_progress_unmanaged_delay)
+ * are unsafe in the early stages of initialization, so we're using this flag
+ * to know when we can move over to normal operation. */
+extern int lcnt_initialization_completed__;
+
+extern const int lcnt_log2_tab64__[];
+
+ERTS_GLB_INLINE
+int lcnt_log2__(Uint64 v);
+
+ERTS_GLB_INLINE
+void lcnt_update_wait_histogram__(erts_lcnt_hist_t *hist, erts_lcnt_time_t *time_waited);
+
+ERTS_GLB_INLINE
+void lcnt_update_stats__(erts_lcnt_lock_stats_t *stats, int lock_in_conflict, erts_lcnt_time_t *time_waited);
+
+ERTS_GLB_INLINE
+erts_lcnt_lock_stats_t *lcnt_get_lock_stats__(erts_lcnt_lock_info_t *info, char *file, unsigned int line);
+
+ERTS_GLB_INLINE
+void lcnt_dec_lock_state__(ethr_atomic_t *l_state);
+
+ERTS_GLB_INLINE
+void lcnt_time__(erts_lcnt_time_t *time);
+
+ERTS_GLB_INLINE
+void lcnt_time_add__(erts_lcnt_time_t *t, erts_lcnt_time_t *d);
+
+ERTS_GLB_INLINE
+void lcnt_time_diff__(erts_lcnt_time_t *d, erts_lcnt_time_t *t1, erts_lcnt_time_t *t0);
+
+ERTS_GLB_INLINE
+void lcnt_retain_carrier__(erts_lcnt_lock_info_carrier_t *carrier);
+
+ERTS_GLB_INLINE
+void lcnt_release_carrier__(erts_lcnt_lock_info_carrier_t *carrier);
+
+ERTS_GLB_INLINE
+lcnt_thread_data_t__ *lcnt_get_thread_data__(void);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE
+void lcnt_time__(erts_lcnt_time_t *time) {
+    /*
+     * erts_sys_hrtime() is the highest resolution
+     * we could find, it may or may not be monotonic...
+     */
+    ErtsMonotonicTime mtime = erts_sys_hrtime();
+    time->s  = (unsigned long) (mtime / 1000000000LL);
+    time->ns = (unsigned long) (mtime - 1000000000LL*time->s);
+}
+
+/* difference d must be non-negative */
+
+ERTS_GLB_INLINE
+void lcnt_time_add__(erts_lcnt_time_t *t, erts_lcnt_time_t *d) {
+    t->s  += d->s;
+    t->ns += d->ns;
+
+    t->s  += t->ns / 1000000000LL;
+    t->ns  = t->ns % 1000000000LL;
+}
+
+ERTS_GLB_INLINE
+void lcnt_time_diff__(erts_lcnt_time_t *d, erts_lcnt_time_t *t1, erts_lcnt_time_t *t0) {
+    long ds;
+    long dns;
+
+    ds  = t1->s  - t0->s;
+    dns = t1->ns - t0->ns;
+
+    /* the difference should not be able to get bigger than 1 sec in ns*/
+
+    if (dns < 0) {
+        ds  -= 1;
+        dns += 1000000000LL;
+    }
+
+    ASSERT(ds >= 0);
+
+    d->s  = ds;
+    d->ns = dns;
+}
+
+ERTS_GLB_INLINE
+int lcnt_log2__(Uint64 v) {
+    v |= v >> 1;
+    v |= v >> 2;
+    v |= v >> 4;
+    v |= v >> 8;
+    v |= v >> 16;
+    v |= v >> 32;
+
+    return lcnt_log2_tab64__[((Uint64)((v - (v >> 1))*0x07EDD5E59A4E28C2)) >> 58];
+}
+
+ERTS_GLB_INLINE
+void lcnt_update_wait_histogram__(erts_lcnt_hist_t *hist, erts_lcnt_time_t *time_waited) {
+    int idx;
+
+    if(time_waited->s > 0 || time_waited->ns > ERTS_LCNT_HISTOGRAM_MAX_NS) {
+        idx = ERTS_LCNT_HISTOGRAM_SLOT_SIZE - 1;
+    } else {
+        unsigned long r = time_waited->ns >> ERTS_LCNT_HISTOGRAM_RSHIFT;
+
+        idx = r ? lcnt_log2__(r) : 0;
+    }
+
+    hist->ns[idx]++;
+}
+
+ERTS_GLB_INLINE
+void lcnt_update_stats__(erts_lcnt_lock_stats_t *stats, int lock_in_conflict, erts_lcnt_time_t *time_waited) {
+    ethr_atomic_inc(&stats->attempts);
+
+    if(lock_in_conflict) {
+        ethr_atomic_inc(&stats->collisions);
+    }
+
+    if(time_waited) {
+        stats->times_waited++;
+
+        lcnt_time_add__(&stats->total_time_waited, time_waited);
+        lcnt_update_wait_histogram__(&stats->wait_time_histogram, time_waited);
+    }
+}
+
+/* If we were installed while the lock was held, r/w_state will be 0 and we
+ * can't tell which unlock or unacquire operation was the last. To get around
+ * this we assume that all excess operations go *towards* zero rather than down
+ * to zero, eventually becoming consistent with the actual state once the lock
+ * is fully released.
+ *
+ * Conflicts might not be counted until the recorded state is fully consistent
+ * with the actual state, but there should be no other ill effects. */
+
+ERTS_GLB_INLINE
+void lcnt_dec_lock_state__(ethr_atomic_t *l_state) {
+    ethr_sint_t state = ethr_atomic_dec_read_acqb(l_state);
+
+    /* We can not assume that state is >= -1 here; unlock and unacquire might
+     * bring it below -1 and race to increment it back. */
+
+    if(state < 0) {
+        ethr_atomic_inc_acqb(l_state);
+    }
+}
+
+ERTS_GLB_INLINE
+erts_lcnt_lock_stats_t *lcnt_get_lock_stats__(erts_lcnt_lock_info_t *info, char *file, unsigned int line) {
+    ASSERT(info->location_count >= 1 && info->location_count <= ERTS_LCNT_MAX_LOCK_LOCATIONS);
+
+    if(erts_lcnt_rt_options & ERTS_LCNT_OPT_LOCATION) {
+        unsigned int i;
+
+        for(i = 0; i < info->location_count; i++) {
+            erts_lcnt_lock_stats_t *stats = &info->location_stats[i];
+
+            if(stats->file == file && stats->line == line) {
+                return stats;
+            }
+        }
+
+        if(info->location_count < ERTS_LCNT_MAX_LOCK_LOCATIONS) {
+            erts_lcnt_lock_stats_t *stats = &info->location_stats[info->location_count];
+
+            stats->file = file;
+            stats->line = line;
+
+            info->location_count++;
+
+            return stats;
+        }
+    }
+
+    return &info->location_stats[0];
+}
+
+ERTS_GLB_INLINE
+lcnt_thread_data_t__ *lcnt_get_thread_data__(void) {
+    lcnt_thread_data_t__ *eltd = (lcnt_thread_data_t__ *)ethr_tsd_get(lcnt_thr_data_key__);
+
+    ASSERT(eltd);
+
+    return eltd;
+}
+
+ERTS_GLB_FORCE_INLINE
+int erts_lcnt_open_ref(erts_lcnt_ref_t *ref, int *handle, erts_lcnt_lock_info_carrier_t **result) {
+    if(!*ethr_atomic_addr(ref) || !lcnt_initialization_completed__) {
+        return 0;
+    }
+
+    (*handle) = lcnt_thr_progress_unmanaged_delay__();
+    (*result) = (erts_lcnt_lock_info_carrier_t*)ethr_atomic_read(ref);
+
+    if(*result) {
+        if(*handle != LCNT_THR_PRGR_DHANDLE_MANAGED) {
+            lcnt_retain_carrier__(*result);
+            lcnt_thr_progress_unmanaged_continue__(*handle);
+        }
+
+        return 1;
+    } else if(*handle != LCNT_THR_PRGR_DHANDLE_MANAGED) {
+        lcnt_thr_progress_unmanaged_continue__(*handle);
+    }
+
+    return 0;
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_close_ref(int handle, erts_lcnt_lock_info_carrier_t *carrier) {
+    if(handle != LCNT_THR_PRGR_DHANDLE_MANAGED) {
+        lcnt_release_carrier__(carrier);
+    }
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock(erts_lcnt_ref_t *ref) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(ref, &handle, &carrier)) {
+        erts_lcnt_lock_idx(carrier, 0);
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock_opt(erts_lcnt_ref_t *ref, Uint16 option) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(ref, &handle, &carrier)) {
+        erts_lcnt_lock_opt_idx(carrier, 0, option);
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock_post(erts_lcnt_ref_t *ref) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(ref, &handle, &carrier)) {
+        erts_lcnt_lock_post_idx(carrier, 0);
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock_post_x(erts_lcnt_ref_t *ref, char *file, unsigned int line) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(ref, &handle, &carrier)) {
+        erts_lcnt_lock_post_x_idx(carrier, 0, file, line);
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_lock_unacquire(erts_lcnt_ref_t *ref) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(ref, &handle, &carrier)) {
+        erts_lcnt_lock_unacquire_idx(carrier, 0);
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_unlock(erts_lcnt_ref_t *ref) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(ref, &handle, &carrier)) {
+        erts_lcnt_unlock_idx(carrier, 0);
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_unlock_opt(erts_lcnt_ref_t *ref, Uint16 option) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(ref, &handle, &carrier)) {
+        erts_lcnt_unlock_opt_idx(carrier, 0, option);
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_trylock(erts_lcnt_ref_t *ref, int result) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(ref, &handle, &carrier)) {
+        erts_lcnt_trylock_idx(carrier, 0, result);
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_FORCE_INLINE
+void erts_lcnt_trylock_opt(erts_lcnt_ref_t *ref, int result, Uint16 option) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(ref, &handle, &carrier)) {
+        erts_lcnt_trylock_opt_idx(carrier, 0, result, option);
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_lock_idx(erts_lcnt_lock_info_carrier_t *carrier, int index) {
+    erts_lcnt_lock_opt_idx(carrier, index, ERTS_LCNT_LO_WRITE);
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_lock_opt_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, Uint16 option) {
+    erts_lcnt_lock_info_t *info = &carrier->entries[index];
+
+    lcnt_thread_data_t__ *eltd = lcnt_get_thread_data__();
+
+    ASSERT(index < carrier->entry_count);
+
+    ASSERT((option & ERTS_LCNT_LO_READ) || (option & ERTS_LCNT_LO_WRITE));
+
+    if(option & ERTS_LCNT_LO_WRITE) {
+        ethr_sint_t w_state, r_state;
+
+        w_state = ethr_atomic_inc_read(&info->w_state) - 1;
+        r_state = ethr_atomic_read(&info->r_state);
+
+        /* We cannot acquire w_lock if either w or r are taken */
+        eltd->lock_in_conflict = (w_state > 0) || (r_state > 0);
+    } else {
+        ethr_sint_t w_state = ethr_atomic_read(&info->w_state);
+
+        /* We cannot acquire r_lock if w_lock is taken */
+        eltd->lock_in_conflict = (w_state > 0);
+    }
+
+    if(option & ERTS_LCNT_LO_READ) {
+        ethr_atomic_inc(&info->r_state);
+    }
+
+    if(eltd->lock_in_conflict) {
+        /* Only set the timer if nobody else has it. This should only happen
+         * when proc_locks acquires several locks "atomically." All other locks
+         * will block the thread when locked (w_state > 0) */
+        if(eltd->timer_set == 0) {
+            lcnt_time__(&eltd->timer);
+        }
+
+        eltd->timer_set++;
+    }
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_lock_post_idx(erts_lcnt_lock_info_carrier_t *carrier, int index) {
+    erts_lcnt_lock_post_x_idx(carrier, index, NULL, 0);
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_lock_post_x_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, char *file, unsigned int line) {
+    erts_lcnt_lock_info_t *info = &carrier->entries[index];
+
+    lcnt_thread_data_t__ *eltd = lcnt_get_thread_data__();
+    erts_lcnt_lock_stats_t *stats;
+
+    ASSERT(index < carrier->entry_count);
+
+#ifdef LCNT_DEBUG_LOCK_FLOW
+    if(!(info->flag & (ERTS_LCNT_LT_RWMUTEX | ERTS_LCNT_LT_RWSPINLOCK))) {
+        ASSERT(ethr_atomic_inc_read(&info->flowstate) == 1);
+    }
+#endif
+
+    /* If the lock was in conflict, update the time spent waiting. */
+    stats = lcnt_get_lock_stats__(info, file, line);
+    if(eltd->timer_set) {
+        erts_lcnt_time_t time_wait;
+        erts_lcnt_time_t timer;
+
+        lcnt_time__(&timer);
+
+        lcnt_time_diff__(&time_wait, &timer, &eltd->timer);
+        lcnt_update_stats__(stats, eltd->lock_in_conflict, &time_wait);
+
+        eltd->timer_set--;
+
+        ASSERT(eltd->timer_set >= 0);
+    } else {
+        lcnt_update_stats__(stats, eltd->lock_in_conflict, NULL);
+    }
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_unlock_idx(erts_lcnt_lock_info_carrier_t *carrier, int index) {
+#ifdef LCNT_DEBUG_LOCK_FLOW
+    erts_lcnt_lock_info_t *info = &carrier->entries[index];
+
+    ASSERT(ethr_atomic_dec_read(&info->flowstate) == 0);
+#endif
+
+    ASSERT(index < carrier->entry_count);
+
+    erts_lcnt_unlock_opt_idx(carrier, index, ERTS_LCNT_LO_WRITE);
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_unlock_opt_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, Uint16 option) {
+    erts_lcnt_lock_info_t *info = &carrier->entries[index];
+
+    ASSERT(index < carrier->entry_count);
+
+    ASSERT((option & ERTS_LCNT_LO_READ) || (option & ERTS_LCNT_LO_WRITE));
+
+    if(option & ERTS_LCNT_LO_WRITE) {
+        lcnt_dec_lock_state__(&info->w_state);
+    }
+
+    if(option & ERTS_LCNT_LO_READ) {
+        lcnt_dec_lock_state__(&info->r_state);
+    }
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_lock_unacquire_idx(erts_lcnt_lock_info_carrier_t *carrier, int index) {
+    erts_lcnt_lock_info_t *info = &carrier->entries[index];
+
+    ASSERT(index < carrier->entry_count);
+
+    lcnt_dec_lock_state__(&info->w_state);
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_trylock_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, int result) {
+#ifdef LCNT_DEBUG_LOCK_FLOW
+    erts_lcnt_lock_info_t *info = &carrier->entries[index];
+
+    ASSERT(result == EBUSY || ethr_atomic_inc_read(&info->flowstate) == 1);
+#endif
+
+    ASSERT(index < carrier->entry_count);
+
+    erts_lcnt_trylock_opt_idx(carrier, index, result, ERTS_LCNT_LO_WRITE);
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_trylock_opt_idx(erts_lcnt_lock_info_carrier_t *carrier, int index, int result, Uint16 option) {
+    erts_lcnt_lock_info_t *info = &carrier->entries[index];
+
+    ASSERT(index < carrier->entry_count);
+
+    ASSERT((option & ERTS_LCNT_LO_READ) || (option & ERTS_LCNT_LO_WRITE));
+
+    if(result != EBUSY) {
+        if(option & ERTS_LCNT_LO_WRITE) {
+            ethr_atomic_inc(&info->w_state);
+        }
+
+        if(option & ERTS_LCNT_LO_READ) {
+            ethr_atomic_inc(&info->r_state);
+        }
+
+        lcnt_update_stats__(&info->location_stats[0], 0, NULL);
+    } else {
+        ethr_atomic_inc(&info->location_stats[0].attempts);
+        ethr_atomic_inc(&info->location_stats[0].collisions);
+    }
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_init_lock_info_x_idx(erts_lcnt_lock_info_carrier_t *carrier, int index,
+                                    const char *name, Uint16 flag, Eterm id) {
+    erts_lcnt_lock_info_t *info = &carrier->entries[index];
+
+    ASSERT(is_immed(id));
+
+    info->flag = flag;
+    info->name = name;
+    info->id = id;
+}
+
+ERTS_GLB_INLINE
+void lcnt_retain_carrier__(erts_lcnt_lock_info_carrier_t *carrier) {
+#ifdef DEBUG
+    ASSERT(ethr_atomic_inc_read_acqb(&carrier->ref_count) >= 2);
+#else
+    ethr_atomic_inc_acqb(&carrier->ref_count);
+#endif
+}
+
+ERTS_GLB_INLINE
+void lcnt_release_carrier__(erts_lcnt_lock_info_carrier_t *carrier) {
+    ethr_sint_t count = ethr_atomic_dec_read_relb(&carrier->ref_count);
+
+    ASSERT(count >= 0);
+
+    if(count == 0) {
+        carrier->deallocate(carrier);
+    }
+}
+
+#endif
 
 #endif /* ifdef  ERTS_ENABLE_LOCK_COUNT  */
 #endif /* ifndef ERTS_LOCK_COUNT_H__     */
diff --git a/erts/emulator/beam/erl_process_lock.c b/erts/emulator/beam/erl_process_lock.c
index c0e7380ed0..59577bf422 100644
--- a/erts/emulator/beam/erl_process_lock.c
+++ b/erts/emulator/beam/erl_process_lock.c
@@ -944,7 +944,7 @@ erts_pid2proc_opt(Process *c_p,
 			erts_proc_inc_refc(proc);
 
 #if ERTS_PROC_LOCK_OWN_IMPL && defined(ERTS_ENABLE_LOCK_COUNT)
-		    erts_lcnt_proc_lock_unaquire(&proc->lock, lcnt_locks);
+		    erts_lcnt_proc_lock_unacquire(&proc->lock, lcnt_locks);
 #endif
 
 		    managed = dhndl == ERTS_THR_PRGR_DHANDLE_MANAGED;
@@ -1127,114 +1127,52 @@ erts_proc_lock_fin(Process *p)
 void erts_lcnt_enable_proc_lock_count(int enable) {
     int ix, max = erts_ptab_max(&erts_proc);
     Process *proc = NULL;
-    for (ix = 0; ix < max; ++ix) {
-	if ((proc = erts_pix2proc(ix)) != NULL)
+    for(ix = 0; ix < max; ++ix) {
+        if((proc = erts_pix2proc(ix)) != NULL) {
             lcnt_enable_proc_lock_count(proc, enable);
+        }
     } /* for all processes */
 }
 
 void erts_lcnt_proc_lock_init(Process *p) {
-    if (!(erts_lcnt_rt_options & ERTS_LCNT_OPT_PROCLOCK)) {
-        erts_lcnt_init_lock_empty(&(p->lock.lcnt_main));
-        erts_lcnt_init_lock_empty(&(p->lock.lcnt_link));
-        erts_lcnt_init_lock_empty(&(p->lock.lcnt_msgq));
-        erts_lcnt_init_lock_empty(&(p->lock.lcnt_btm));
-        erts_lcnt_init_lock_empty(&(p->lock.lcnt_status));
-        erts_lcnt_init_lock_empty(&(p->lock.lcnt_trace));
-    } else { /* now the common case */
-        Eterm pid = (p->common.id != ERTS_INVALID_PID) ? p->common.id : NIL;
-        erts_lcnt_init_lock_x(&(p->lock.lcnt_main),  "proc_main",  ERTS_LCNT_LT_PROCLOCK, pid);
-        erts_lcnt_init_lock_x(&(p->lock.lcnt_link),  "proc_link",  ERTS_LCNT_LT_PROCLOCK, pid);
-        erts_lcnt_init_lock_x(&(p->lock.lcnt_msgq),  "proc_msgq",  ERTS_LCNT_LT_PROCLOCK, pid);
-        erts_lcnt_init_lock_x(&(p->lock.lcnt_btm),   "proc_btm",   ERTS_LCNT_LT_PROCLOCK, pid);
-        erts_lcnt_init_lock_x(&(p->lock.lcnt_status),"proc_status",ERTS_LCNT_LT_PROCLOCK, pid);
-        erts_lcnt_init_lock_x(&(p->lock.lcnt_trace), "proc_trace", ERTS_LCNT_LT_PROCLOCK, pid);
-    } /* the lock names should really be aligned to four characters */
+    erts_lcnt_init_ref(&p->lock.lcnt_carrier);
+
+    if (erts_lcnt_rt_options & ERTS_LCNT_OPT_PROCLOCK) {
+        lcnt_enable_proc_lock_count(p, 1);
+    }
 } /* logic reversed */
 
 void erts_lcnt_proc_lock_destroy(Process *p) {
-    erts_lcnt_destroy_lock(&(p->lock.lcnt_main));
-    erts_lcnt_destroy_lock(&(p->lock.lcnt_link));
-    erts_lcnt_destroy_lock(&(p->lock.lcnt_msgq));
-    erts_lcnt_destroy_lock(&(p->lock.lcnt_btm));
-    erts_lcnt_destroy_lock(&(p->lock.lcnt_status));
-    erts_lcnt_destroy_lock(&(p->lock.lcnt_trace));
+    erts_lcnt_uninstall(&p->lock.lcnt_carrier);
 }
 
 static void lcnt_enable_proc_lock_count(Process *proc, int enable) {
     if (enable) {
-        if (!ERTS_LCNT_LOCK_TYPE(&(proc->lock.lcnt_main))) {
-            erts_lcnt_proc_lock_init(proc);
-        }
-    }
-    else {
-        if (ERTS_LCNT_LOCK_TYPE(&(proc->lock.lcnt_main))) {
-            erts_lcnt_proc_lock_destroy(proc);
-        }
-    }
-}
-
-void erts_lcnt_proc_lock(erts_proc_lock_t *lock, ErtsProcLocks locks) {
-    if (!(erts_lcnt_rt_options & ERTS_LCNT_OPT_PROCLOCK)) return;
-    if (locks & ERTS_PROC_LOCK_MAIN) { erts_lcnt_lock(&(lock->lcnt_main)); }
-    if (locks & ERTS_PROC_LOCK_LINK) { erts_lcnt_lock(&(lock->lcnt_link)); }
-    if (locks & ERTS_PROC_LOCK_MSGQ) { erts_lcnt_lock(&(lock->lcnt_msgq)); }
-    if (locks & ERTS_PROC_LOCK_BTM) { erts_lcnt_lock(&(lock->lcnt_btm)); }
-    if (locks & ERTS_PROC_LOCK_STATUS) { erts_lcnt_lock(&(lock->lcnt_status)); }
-    if (locks & ERTS_PROC_LOCK_TRACE) { erts_lcnt_lock(&(lock->lcnt_trace)); }
-}
-
-void erts_lcnt_proc_lock_post_x(erts_proc_lock_t *lock, ErtsProcLocks locks,
-                                char *file, unsigned int line) {
-    if (!(erts_lcnt_rt_options & ERTS_LCNT_OPT_PROCLOCK)) return;
-    if (locks & ERTS_PROC_LOCK_MAIN) {
-	erts_lcnt_lock_post_x(&(lock->lcnt_main), file, line);
-    }
-    if (locks & ERTS_PROC_LOCK_LINK) {
-	erts_lcnt_lock_post_x(&(lock->lcnt_link), file, line);
-    }
-    if (locks & ERTS_PROC_LOCK_MSGQ) {
-        erts_lcnt_lock_post_x(&(lock->lcnt_msgq), file, line);
-    }
-    if (locks & ERTS_PROC_LOCK_BTM) {
-        erts_lcnt_lock_post_x(&(lock->lcnt_btm), file, line);
-    }
-    if (locks & ERTS_PROC_LOCK_STATUS) {
-	erts_lcnt_lock_post_x(&(lock->lcnt_status), file, line);
-    }
-    if (locks & ERTS_PROC_LOCK_TRACE) {
-        erts_lcnt_lock_post_x(&(lock->lcnt_trace), file, line);
+        erts_lcnt_lock_info_carrier_t *carrier;
+        Eterm pid;
+
+        carrier = erts_lcnt_create_lock_info_carrier(ERTS_LCNT_PROCLOCK_COUNT);
+        pid = (proc->common.id != ERTS_INVALID_PID) ? proc->common.id : NIL;
+
+        erts_lcnt_init_lock_info_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MAIN,
+            "proc_main", ERTS_LCNT_LT_PROCLOCK, pid);
+        erts_lcnt_init_lock_info_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_LINK,
+            "proc_link", ERTS_LCNT_LT_PROCLOCK, pid);
+        erts_lcnt_init_lock_info_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MSGQ,
+            "proc_msgq", ERTS_LCNT_LT_PROCLOCK, pid);
+        erts_lcnt_init_lock_info_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_BTM,
+            "proc_btm", ERTS_LCNT_LT_PROCLOCK, pid);
+        erts_lcnt_init_lock_info_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_STATUS,
+            "proc_status",ERTS_LCNT_LT_PROCLOCK, pid);
+        erts_lcnt_init_lock_info_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_TRACE,
+            "proc_trace", ERTS_LCNT_LT_PROCLOCK, pid);
+
+        erts_lcnt_install(&proc->lock.lcnt_carrier, carrier);
+    } else {
+        erts_lcnt_proc_lock_destroy(proc);
     }
 }
 
-void erts_lcnt_proc_lock_unaquire(erts_proc_lock_t *lock, ErtsProcLocks locks) {
-    if (!(erts_lcnt_rt_options & ERTS_LCNT_OPT_PROCLOCK)) return;
-    if (locks & ERTS_PROC_LOCK_MAIN) { erts_lcnt_lock_unaquire(&(lock->lcnt_main)); }
-    if (locks & ERTS_PROC_LOCK_LINK) { erts_lcnt_lock_unaquire(&(lock->lcnt_link)); }
-    if (locks & ERTS_PROC_LOCK_MSGQ) { erts_lcnt_lock_unaquire(&(lock->lcnt_msgq)); }
-    if (locks & ERTS_PROC_LOCK_BTM) { erts_lcnt_lock_unaquire(&(lock->lcnt_btm)); }
-    if (locks & ERTS_PROC_LOCK_STATUS) { erts_lcnt_lock_unaquire(&(lock->lcnt_status)); }
-    if (locks & ERTS_PROC_LOCK_TRACE) { erts_lcnt_lock_unaquire(&(lock->lcnt_trace)); }
-}
-
-void erts_lcnt_proc_unlock(erts_proc_lock_t *lock, ErtsProcLocks locks) {
-    if (!(erts_lcnt_rt_options & ERTS_LCNT_OPT_PROCLOCK)) return;
-    if (locks & ERTS_PROC_LOCK_MAIN) { erts_lcnt_unlock(&(lock->lcnt_main)); }
-    if (locks & ERTS_PROC_LOCK_LINK) { erts_lcnt_unlock(&(lock->lcnt_link)); }
-    if (locks & ERTS_PROC_LOCK_MSGQ) { erts_lcnt_unlock(&(lock->lcnt_msgq)); }
-    if (locks & ERTS_PROC_LOCK_BTM) { erts_lcnt_unlock(&(lock->lcnt_btm)); }
-    if (locks & ERTS_PROC_LOCK_STATUS) { erts_lcnt_unlock(&(lock->lcnt_status)); }
-    if (locks & ERTS_PROC_LOCK_TRACE) { erts_lcnt_unlock(&(lock->lcnt_trace)); }
-}
-void erts_lcnt_proc_trylock(erts_proc_lock_t *lock, ErtsProcLocks locks, int res) {
-    if (!(erts_lcnt_rt_options & ERTS_LCNT_OPT_PROCLOCK)) return;
-    if (locks & ERTS_PROC_LOCK_MAIN) { erts_lcnt_trylock(&(lock->lcnt_main), res); }
-    if (locks & ERTS_PROC_LOCK_LINK) { erts_lcnt_trylock(&(lock->lcnt_link), res); }
-    if (locks & ERTS_PROC_LOCK_MSGQ) { erts_lcnt_trylock(&(lock->lcnt_msgq), res); }
-    if (locks & ERTS_PROC_LOCK_BTM) { erts_lcnt_trylock(&(lock->lcnt_btm), res); }
-    if (locks & ERTS_PROC_LOCK_STATUS) { erts_lcnt_trylock(&(lock->lcnt_status), res); }
-    if (locks & ERTS_PROC_LOCK_TRACE) { erts_lcnt_trylock(&(lock->lcnt_trace), res); }
-} /* reversed logic */
 #endif /* ERTS_ENABLE_LOCK_COUNT */
 
 
diff --git a/erts/emulator/beam/erl_process_lock.h b/erts/emulator/beam/erl_process_lock.h
index 6e704b185d..b4a5ef3f28 100644
--- a/erts/emulator/beam/erl_process_lock.h
+++ b/erts/emulator/beam/erl_process_lock.h
@@ -78,13 +78,19 @@ typedef struct erts_proc_lock_t_ {
     ErtsProcLocks flags;
 #endif
     erts_tse_t *queue[ERTS_PROC_LOCK_MAX_BIT+1];
-#ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_lock_t lcnt_main;
-    erts_lcnt_lock_t lcnt_link;
-    erts_lcnt_lock_t lcnt_msgq;
-    erts_lcnt_lock_t lcnt_btm;
-    erts_lcnt_lock_t lcnt_status;
-    erts_lcnt_lock_t lcnt_trace;
+#if defined(ERTS_ENABLE_LOCK_COUNT) && !ERTS_PROC_LOCK_RAW_MUTEX_IMPL
+    /* Each erts_mtx_t has its own lock counter ^ */
+
+    #define ERTS_LCNT_PROCLOCK_IDX_MAIN 0
+    #define ERTS_LCNT_PROCLOCK_IDX_LINK 1
+    #define ERTS_LCNT_PROCLOCK_IDX_MSGQ 2
+    #define ERTS_LCNT_PROCLOCK_IDX_BTM 3
+    #define ERTS_LCNT_PROCLOCK_IDX_STATUS 4
+    #define ERTS_LCNT_PROCLOCK_IDX_TRACE 5
+
+    #define ERTS_LCNT_PROCLOCK_COUNT 6
+
+    erts_lcnt_ref_t lcnt_carrier;
 #endif
 #elif ERTS_PROC_LOCK_RAW_MUTEX_IMPL
     erts_mtx_t main;
@@ -245,14 +251,169 @@ typedef struct erts_proc_lock_t_ {
 
 void erts_lcnt_proc_lock_init(Process *p);
 void erts_lcnt_proc_lock_destroy(Process *p);
+
+ERTS_GLB_INLINE
 void erts_lcnt_proc_lock(erts_proc_lock_t *lock, ErtsProcLocks locks);
+ERTS_GLB_INLINE
 void erts_lcnt_proc_lock_post_x(erts_proc_lock_t *lock, ErtsProcLocks locks, char *file, unsigned int line);
-void erts_lcnt_proc_lock_unaquire(erts_proc_lock_t *lock, ErtsProcLocks locks);
+ERTS_GLB_INLINE
+void erts_lcnt_proc_lock_unacquire(erts_proc_lock_t *lock, ErtsProcLocks locks);
+ERTS_GLB_INLINE
 void erts_lcnt_proc_unlock(erts_proc_lock_t *lock, ErtsProcLocks locks);
+ERTS_GLB_INLINE
 void erts_lcnt_proc_trylock(erts_proc_lock_t *lock, ErtsProcLocks locks, int res);
 
 void erts_lcnt_enable_proc_lock_count(int enable);
 
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE
+void erts_lcnt_proc_lock(erts_proc_lock_t *lock, ErtsProcLocks locks) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(&lock->lcnt_carrier, &handle, &carrier)) {
+        if (locks & ERTS_PROC_LOCK_MAIN) {
+            erts_lcnt_lock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MAIN);
+        }
+        if (locks & ERTS_PROC_LOCK_LINK) {
+            erts_lcnt_lock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_LINK);
+        }
+        if (locks & ERTS_PROC_LOCK_MSGQ) {
+            erts_lcnt_lock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MSGQ);
+        }
+        if (locks & ERTS_PROC_LOCK_BTM) {
+            erts_lcnt_lock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_BTM);
+        }
+        if (locks & ERTS_PROC_LOCK_STATUS) {
+            erts_lcnt_lock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_STATUS);
+        }
+        if (locks & ERTS_PROC_LOCK_TRACE) {
+            erts_lcnt_lock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_TRACE);
+        }
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_proc_lock_post_x(erts_proc_lock_t *lock, ErtsProcLocks locks,
+                                char *file, unsigned int line) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(&lock->lcnt_carrier, &handle, &carrier)) {
+        if (locks & ERTS_PROC_LOCK_MAIN) {
+            erts_lcnt_lock_post_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MAIN, file, line);
+        }
+        if (locks & ERTS_PROC_LOCK_LINK) {
+            erts_lcnt_lock_post_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_LINK, file, line);
+        }
+        if (locks & ERTS_PROC_LOCK_MSGQ) {
+            erts_lcnt_lock_post_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MSGQ, file, line);
+        }
+        if (locks & ERTS_PROC_LOCK_BTM) {
+            erts_lcnt_lock_post_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_BTM, file, line);
+        }
+        if (locks & ERTS_PROC_LOCK_STATUS) {
+            erts_lcnt_lock_post_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_STATUS, file, line);
+        }
+        if (locks & ERTS_PROC_LOCK_TRACE) {
+            erts_lcnt_lock_post_x_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_TRACE, file, line);
+        }
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_proc_lock_unacquire(erts_proc_lock_t *lock, ErtsProcLocks locks) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(&lock->lcnt_carrier, &handle, &carrier)) {
+        if (locks & ERTS_PROC_LOCK_MAIN) {
+            erts_lcnt_lock_unacquire_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MAIN);
+        }
+        if (locks & ERTS_PROC_LOCK_LINK) {
+            erts_lcnt_lock_unacquire_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_LINK);
+        }
+        if (locks & ERTS_PROC_LOCK_MSGQ) {
+            erts_lcnt_lock_unacquire_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MSGQ);
+        }
+        if (locks & ERTS_PROC_LOCK_BTM) {
+            erts_lcnt_lock_unacquire_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_BTM);
+        }
+        if (locks & ERTS_PROC_LOCK_STATUS) {
+            erts_lcnt_lock_unacquire_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_STATUS);
+        }
+        if (locks & ERTS_PROC_LOCK_TRACE) {
+            erts_lcnt_lock_unacquire_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_TRACE);
+        }
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_proc_unlock(erts_proc_lock_t *lock, ErtsProcLocks locks) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(&lock->lcnt_carrier, &handle, &carrier)) {
+        if (locks & ERTS_PROC_LOCK_MAIN) {
+            erts_lcnt_unlock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MAIN);
+        }
+        if (locks & ERTS_PROC_LOCK_LINK) {
+            erts_lcnt_unlock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_LINK);
+        }
+        if (locks & ERTS_PROC_LOCK_MSGQ) {
+            erts_lcnt_unlock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MSGQ);
+        }
+        if (locks & ERTS_PROC_LOCK_BTM) {
+            erts_lcnt_unlock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_BTM);
+        }
+        if (locks & ERTS_PROC_LOCK_STATUS) {
+            erts_lcnt_unlock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_STATUS);
+        }
+        if (locks & ERTS_PROC_LOCK_TRACE) {
+            erts_lcnt_unlock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_TRACE);
+        }
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+}
+
+ERTS_GLB_INLINE
+void erts_lcnt_proc_trylock(erts_proc_lock_t *lock, ErtsProcLocks locks, int res) {
+    erts_lcnt_lock_info_carrier_t *carrier;
+    int handle;
+
+    if(erts_lcnt_open_ref(&lock->lcnt_carrier, &handle, &carrier)) {
+        if (locks & ERTS_PROC_LOCK_MAIN) {
+            erts_lcnt_trylock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MAIN, res);
+        }
+        if (locks & ERTS_PROC_LOCK_LINK) {
+            erts_lcnt_trylock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_LINK, res);
+        }
+        if (locks & ERTS_PROC_LOCK_MSGQ) {
+            erts_lcnt_trylock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_MSGQ, res);
+        }
+        if (locks & ERTS_PROC_LOCK_BTM) {
+            erts_lcnt_trylock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_BTM, res);
+        }
+        if (locks & ERTS_PROC_LOCK_STATUS) {
+            erts_lcnt_trylock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_STATUS, res);
+        }
+        if (locks & ERTS_PROC_LOCK_TRACE) {
+            erts_lcnt_trylock_idx(carrier, ERTS_LCNT_PROCLOCK_IDX_TRACE, res);
+        }
+
+        erts_lcnt_close_ref(handle, carrier);
+    }
+} /* reversed logic */
+
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
 #endif /* ERTS_ENABLE_LOCK_COUNT*/
 
 
diff --git a/erts/emulator/beam/erl_thr_progress.c b/erts/emulator/beam/erl_thr_progress.c
index 700ed90def..2a9f276e02 100644
--- a/erts/emulator/beam/erl_thr_progress.c
+++ b/erts/emulator/beam/erl_thr_progress.c
@@ -321,13 +321,23 @@ tmp_thr_prgr_data(ErtsSchedulerData *esdp)
     ErtsThrPrgrData *tpd = perhaps_thr_prgr_data(esdp);
 
     if (!tpd) {
-	/*
-	 * We only allocate the part up to the wakeup_request field
-	 * which is the first field only used by registered threads
-	 */
-	tpd = erts_alloc(ERTS_ALC_T_T_THR_PRGR_DATA,
-			 offsetof(ErtsThrPrgrData, wakeup_request));
-	init_tmp_thr_prgr_data(tpd);
+        /*
+         * We only allocate the part up to the wakeup_request field which is
+         * the first field only used by registered threads
+         */
+        size_t alloc_size = offsetof(ErtsThrPrgrData, wakeup_request);
+
+        /* We may land here as a result of unmanaged_delay being called from
+         * the lock counting module, which in turn might be called from within
+         * the allocator, so we use plain malloc to avoid deadlocks. */
+        tpd =
+#ifdef ERTS_ENABLE_LOCK_COUNT
+            malloc(alloc_size);
+#else
+            erts_alloc(ERTS_ALC_T_T_THR_PRGR_DATA, alloc_size);
+#endif
+
+        init_tmp_thr_prgr_data(tpd);
     }
 
     return tpd;
@@ -337,8 +347,13 @@ static ERTS_INLINE void
 return_tmp_thr_prgr_data(ErtsThrPrgrData *tpd)
 {
     if (tpd->is_temporary) {
-	erts_tsd_set(erts_thr_prgr_data_key__, NULL);
-	erts_free(ERTS_ALC_T_T_THR_PRGR_DATA, tpd);
+        erts_tsd_set(erts_thr_prgr_data_key__, NULL);
+
+#ifdef ERTS_ENABLE_LOCK_COUNT
+        free(tpd);
+#else
+        erts_free(ERTS_ALC_T_T_THR_PRGR_DATA, tpd);
+#endif
     }
 }
 
diff --git a/erts/emulator/beam/erl_threads.h b/erts/emulator/beam/erl_threads.h
index 28ff5d3a42..f7b53f5ef3 100644
--- a/erts/emulator/beam/erl_threads.h
+++ b/erts/emulator/beam/erl_threads.h
@@ -307,7 +307,7 @@ typedef struct {
     erts_lc_lock_t lc;
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_lock_t lcnt;
+    erts_lcnt_ref_t lcnt;
 #endif
 
 } erts_mtx_t;
@@ -320,7 +320,7 @@ typedef struct {
     erts_lc_lock_t lc;
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_lock_t lcnt;
+    erts_lcnt_ref_t lcnt;
 #endif
 } erts_rwmtx_t;
 
@@ -365,7 +365,7 @@ typedef struct {
     erts_lc_lock_t lc;
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_lock_t lcnt;
+    erts_lcnt_ref_t lcnt;
 #endif
 } erts_spinlock_t;
 
@@ -376,7 +376,7 @@ typedef struct {
     erts_lc_lock_t lc;
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_lock_t lcnt;
+    erts_lcnt_ref_t lcnt;
 #endif
 } erts_rwlock_t;
 
@@ -2169,7 +2169,8 @@ erts_mtx_init_x(erts_mtx_t *mtx, char *name, Eterm extra)
     erts_lc_init_lock_x(&mtx->lc, name, ERTS_LC_FLG_LT_MUTEX, extra);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock_x(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX, extra);
+    erts_lcnt_init_ref(&mtx->lcnt);
+    erts_lcnt_install_new_lock_info_x(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX, extra);
 #endif
 #endif
 }
@@ -2185,7 +2186,10 @@ erts_mtx_init_x_opt(erts_mtx_t *mtx, char *name, Eterm extra, Uint16 opt)
     erts_lc_init_lock_x(&mtx->lc, name, ERTS_LC_FLG_LT_MUTEX, extra);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock_x(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX | opt, extra);
+    erts_lcnt_init_ref(&mtx->lcnt);
+    if(!(opt & ERTS_LCNT_LT_DISABLE)) { // Incorrect, but preserves the old interface.
+        erts_lcnt_install_new_lock_info_x(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX | opt, extra);
+    }
 #endif
 #endif
 }
@@ -2202,7 +2206,10 @@ erts_mtx_init_locked_x_opt(erts_mtx_t *mtx, char *name, Eterm extra, Uint16 opt)
     erts_lc_init_lock_x(&mtx->lc, name, ERTS_LC_FLG_LT_MUTEX, extra);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock_x(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX | opt, extra);
+    erts_lcnt_init_ref(&mtx->lcnt);
+    if(!(opt & ERTS_LCNT_LT_DISABLE)) { // Incorrect, but preserves the old interface.
+        erts_lcnt_install_new_lock_info_x(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX, extra);
+    }
 #endif
     ethr_mutex_lock(&mtx->mtx);
 #ifdef ERTS_ENABLE_LOCK_CHECK
@@ -2225,7 +2232,8 @@ erts_mtx_init(erts_mtx_t *mtx, char *name)
     erts_lc_init_lock(&mtx->lc, name, ERTS_LC_FLG_LT_MUTEX);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX);
+    erts_lcnt_init_ref(&mtx->lcnt);
+    erts_lcnt_install_new_lock_info(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX);
 #endif
 #endif
 }
@@ -2241,7 +2249,8 @@ erts_mtx_init_locked(erts_mtx_t *mtx, char *name)
     erts_lc_init_lock(&mtx->lc, name, ERTS_LC_FLG_LT_MUTEX);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX);
+    erts_lcnt_init_ref(&mtx->lcnt);
+    erts_lcnt_install_new_lock_info(&mtx->lcnt, name, ERTS_LCNT_LT_MUTEX);
 #endif
     ethr_mutex_lock(&mtx->mtx);
 #ifdef ERTS_ENABLE_LOCK_CHECK
@@ -2262,7 +2271,7 @@ erts_mtx_destroy(erts_mtx_t *mtx)
     erts_lc_destroy_lock(&mtx->lc);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_destroy_lock(&mtx->lcnt);
+    erts_lcnt_uninstall(&mtx->lcnt);
 #endif
     res = ethr_mutex_destroy(&mtx->mtx);
     if (res != 0) {
@@ -2481,10 +2490,11 @@ erts_rwmtx_init_opt_x(erts_rwmtx_t *rwmtx,
     erts_lc_init_lock_x(&rwmtx->lc, name, ERTS_LC_FLG_LT_RWMUTEX, extra);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
+    erts_lcnt_init_ref(&rwmtx->lcnt);
     if (name && name[0] == '\0')
-      erts_lcnt_init_lock_x(&rwmtx->lcnt, NULL, ERTS_LCNT_LT_RWMUTEX, extra);
+        erts_lcnt_install_new_lock_info_x(&rwmtx->lcnt, NULL, ERTS_LCNT_LT_RWMUTEX, extra);
     else
-      erts_lcnt_init_lock_x(&rwmtx->lcnt, name, ERTS_LCNT_LT_RWMUTEX, extra);
+        erts_lcnt_install_new_lock_info_x(&rwmtx->lcnt, name, ERTS_LCNT_LT_RWMUTEX, extra);
 #endif
 #endif
 }
@@ -2510,7 +2520,8 @@ erts_rwmtx_init_opt(erts_rwmtx_t *rwmtx,
     erts_lc_init_lock(&rwmtx->lc, name, ERTS_LC_FLG_LT_RWMUTEX);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock(&rwmtx->lcnt, name, ERTS_LCNT_LT_RWMUTEX);
+    erts_lcnt_init_ref(&rwmtx->lcnt);
+    erts_lcnt_install_new_lock_info(&rwmtx->lcnt, name, ERTS_LCNT_LT_RWMUTEX);
 #endif
 #endif
 }
@@ -2530,7 +2541,7 @@ erts_rwmtx_destroy(erts_rwmtx_t *rwmtx)
     erts_lc_destroy_lock(&rwmtx->lc);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_destroy_lock(&rwmtx->lcnt);
+    erts_lcnt_uninstall(&rwmtx->lcnt);
 #endif
     res = ethr_rwmutex_destroy(&rwmtx->rwmtx);
     if (res != 0) {
@@ -3085,7 +3096,8 @@ erts_spinlock_init_x(erts_spinlock_t *lock, char *name, Eterm extra)
     erts_lc_init_lock_x(&lock->lc, name, ERTS_LC_FLG_LT_SPINLOCK, extra);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock_x(&lock->lcnt, name, ERTS_LCNT_LT_SPINLOCK, extra);
+    erts_lcnt_init_ref(&lock->lcnt);
+    erts_lcnt_install_new_lock_info_x(&lock->lcnt, name, ERTS_LCNT_LT_SPINLOCK, extra);
 #endif
 #else
     (void)lock;
@@ -3104,7 +3116,8 @@ erts_spinlock_init_x_opt(erts_spinlock_t *lock, char *name, Eterm extra,
     erts_lc_init_lock_x(&lock->lc, name, ERTS_LC_FLG_LT_SPINLOCK, extra);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock_x(&lock->lcnt, name, ERTS_LCNT_LT_SPINLOCK|opt, extra);
+    erts_lcnt_init_ref(&lock->lcnt);
+    erts_lcnt_install_new_lock_info_x(&lock->lcnt, name, ERTS_LCNT_LT_SPINLOCK | opt, extra);
 #endif
 #else
     (void)lock;
@@ -3123,7 +3136,8 @@ erts_spinlock_init(erts_spinlock_t *lock, char *name)
     erts_lc_init_lock(&lock->lc, name, ERTS_LC_FLG_LT_SPINLOCK);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock(&lock->lcnt, name, ERTS_LCNT_LT_SPINLOCK);
+    erts_lcnt_init_ref(&lock->lcnt);
+    erts_lcnt_install_new_lock_info(&lock->lcnt, name, ERTS_LCNT_LT_SPINLOCK);
 #endif
 #else
     (void)lock;
@@ -3139,7 +3153,7 @@ erts_spinlock_destroy(erts_spinlock_t *lock)
     erts_lc_destroy_lock(&lock->lc);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_destroy_lock(&lock->lcnt);
+    erts_lcnt_uninstall(&lock->lcnt);
 #endif
     res = ethr_spinlock_destroy(&lock->slck);
     if (res != 0) {
@@ -3228,7 +3242,8 @@ erts_rwlock_init_x(erts_rwlock_t *lock, char *name, Eterm extra)
     erts_lc_init_lock_x(&lock->lc, name, ERTS_LC_FLG_LT_RWSPINLOCK, extra);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock_x(&lock->lcnt, name, ERTS_LCNT_LT_RWSPINLOCK, extra);
+    erts_lcnt_init_ref(&lock->lcnt);
+    erts_lcnt_install_new_lock_info_x(&lock->lcnt, name, ERTS_LCNT_LT_RWSPINLOCK, extra);
 #endif
 #else
     (void)lock;
@@ -3246,7 +3261,8 @@ erts_rwlock_init(erts_rwlock_t *lock, char *name)
     erts_lc_init_lock(&lock->lc, name, ERTS_LC_FLG_LT_RWSPINLOCK);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init_lock(&lock->lcnt, name, ERTS_LCNT_LT_RWSPINLOCK);
+    erts_lcnt_init_ref(&lock->lcnt);
+    erts_lcnt_install_new_lock_info(&lock->lcnt, name, ERTS_LCNT_LT_RWSPINLOCK);
 #endif
 #else
     (void)lock;
@@ -3262,7 +3278,7 @@ erts_rwlock_destroy(erts_rwlock_t *lock)
     erts_lc_destroy_lock(&lock->lc);
 #endif
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_destroy_lock(&lock->lcnt);
+    erts_lcnt_uninstall(&lock->lcnt);
 #endif
     res = ethr_rwlock_destroy(&lock->rwlck);
     if (res != 0) {
diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index d25e53ada0..11cb2dfddf 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -3461,39 +3461,34 @@ void erts_init_io(int port_tab_size,
 static ERTS_INLINE void lcnt_enable_drv_lock_count(erts_driver_t *dp, int enable)
 {
     if (dp->lock) {
-	if (enable)
-	    erts_lcnt_init_lock_x(&dp->lock->lcnt,
-				  "driver_lock",
-				  ERTS_LCNT_LT_MUTEX,
-				  erts_atom_put((byte*)dp->name,
-						sys_strlen(dp->name),
-						ERTS_ATOM_ENC_LATIN1,
-						1));
-
-	else
-	    erts_lcnt_destroy_lock(&dp->lock->lcnt);
-
-    }
+	if (enable) {
+			Eterm name_as_atom = erts_atom_put((byte*)dp->name, sys_strlen(dp->name),
+											   ERTS_ATOM_ENC_LATIN1, 1);
+			erts_lcnt_install_new_lock_info_x(&dp->lock->lcnt,
+				"driver_lock", ERTS_LCNT_LT_MUTEX, name_as_atom);
+		} else {
+			erts_lcnt_uninstall(&dp->lock->lcnt);
+		}
+	}
 }
 
 static ERTS_INLINE void lcnt_enable_port_lock_count(Port *prt, int enable)
 {
     erts_aint32_t state = erts_atomic32_read_nob(&prt->state);
-    if (!enable) {
-	erts_lcnt_destroy_lock(&prt->sched.mtx.lcnt);
-	if (state & ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK)
-	    erts_lcnt_destroy_lock(&prt->lock->lcnt);
-    }
-    else {
-	erts_lcnt_init_lock_x(&prt->sched.mtx.lcnt,
-			      "port_sched_lock",
-			      ERTS_LCNT_LT_MUTEX,
-			      prt->common.id);
-	if (state & ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK)
-	    erts_lcnt_init_lock_x(&prt->lock->lcnt,
-				  "port_lock",
-				  ERTS_LCNT_LT_MUTEX,
-				  prt->common.id);
+
+    if(enable) {
+		erts_lcnt_install_new_lock_info_x(&prt->sched.mtx.lcnt,
+			"port_sched_lock", ERTS_LCNT_LT_MUTEX,prt->common.id);
+
+		if (state & ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK) {
+			erts_lcnt_install_new_lock_info_x(&prt->lock->lcnt,
+				"port_lock", ERTS_LCNT_LT_MUTEX, prt->common.id);
+		}
+    } else {
+		erts_lcnt_uninstall(&prt->sched.mtx.lcnt);
+		if (state & ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK) {
+			erts_lcnt_uninstall(&prt->lock->lcnt);
+		}
     }
 }
 
@@ -3701,7 +3696,7 @@ deliver_result(Port *prt, Eterm sender, Eterm pid, Eterm res)
     ERTS_SMP_CHK_NO_PROC_LOCKS;
 
     ASSERT(!prt || prt->common.id == sender);
-#ifdef ERTS_SMP
+#if defined(ERTS_SMP) && defined(ERTS_ENABLE_LOCK_CHECK)
     ASSERT(!prt || erts_lc_is_port_locked(prt));
 #endif
 
diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index 457cada745..0fb25c2082 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -42,6 +42,7 @@
 #include "dist.h"
 #include "erl_printf.h"
 #include "erl_threads.h"
+#include "erl_lock_count.h"
 #include "erl_smp.h"
 #include "erl_time.h"
 #include "erl_thr_progress.h"
diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 0079912b10..e86258b5e0 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -438,14 +438,18 @@ erts_sys_pre_init(void)
     /* After creation in parent */
     eid.thread_create_parent_func = thr_create_cleanup,
 
+#ifdef ERTS_ENABLE_LOCK_COUNT
+    erts_lcnt_pre_thr_init();
+#endif
+
     erts_thr_init(&eid);
 
-#ifdef ERTS_ENABLE_LOCK_CHECK
-    erts_lc_init();
+#ifdef ERTS_ENABLE_LOCK_COUNT
+    erts_lcnt_post_thr_init();
 #endif
 
-#ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init();
+#ifdef ERTS_ENABLE_LOCK_CHECK
+    erts_lc_init();
 #endif
 
 #endif /* USE_THREADS */
diff --git a/erts/emulator/sys/win32/sys.c b/erts/emulator/sys/win32/sys.c
index 28019e306c..15c59109b1 100644
--- a/erts/emulator/sys/win32/sys.c
+++ b/erts/emulator/sys/win32/sys.c
@@ -3195,15 +3195,22 @@ erts_sys_pre_init(void)
     /* After creation in parent */
     eid.thread_create_parent_func = thr_create_cleanup;
 
-    erts_thr_init(&eid);
-#ifdef ERTS_ENABLE_LOCK_CHECK
-    erts_lc_init();
+#ifdef ERTS_ENABLE_LOCK_COUNT
+    erts_lcnt_pre_thr_init();
 #endif
+
+    erts_thr_init(&eid);
+
 #ifdef ERTS_ENABLE_LOCK_COUNT
-    erts_lcnt_init();
+    erts_lcnt_post_thr_init();
 #endif
+
+#ifdef ERTS_ENABLE_LOCK_CHECK
+    erts_lc_init();
 #endif
 
+#endif /* USE_THREADS */
+
     erts_init_sys_time_sup();
 
     erts_smp_atomic_init_nob(&sys_misc_mem_sz, 0);
diff --git a/lib/tools/doc/src/lcnt.xml b/lib/tools/doc/src/lcnt.xml
index 6e66a957ab..590049e681 100644
--- a/lib/tools/doc/src/lcnt.xml
+++ b/lib/tools/doc/src/lcnt.xml
@@ -109,14 +109,6 @@
 		    statistics. If the server held any lock statistics data before the collect then
 		    that data is lost.
 		</p>
-		<note>
-		    <p>
-			When collection occurs the runtime system transitions to a single thread,
-			blocking all other threads. No other tasks will be scheduled during this
-			operation. Depending on the size of the data this might take a long time
-			(several seconds) and cause timeouts in the system.
-		    </p>
-		</note>
 	    </desc>
 	</func>