Merge branch 'rickard/barriers/OTP-9281' into dev

* rickard/barriers/OTP-9281:
  Silence warnings
  Fix build with hipe on amd64
  Reduce number of atomic ops
  Use 32-bit atomic for port snapshot
  Remove pointless erts_ports_alive variable
  Ensure quick break
  Ensure that all rehashing information are seen when done
  Ensure that stack updates are seen when stack is released
  Add needed barriers for write_concurrency tables
  Homogenize memory barriers on atomics

11 files changed, 141 insertions, 76 deletions

diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index 327620772f..de76cb9680 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -76,6 +76,7 @@ atom allocator_sizes
 atom alloc_util_allocators
 atom allow_passive_connect
 atom already_loaded
+atom amd64
 atom anchored
 atom and
 atom andalso
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index d5d113200a..fb90a7d4f7 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -5325,7 +5325,7 @@ void process_main(void)
 	 ep->code[3] = (BeamInstr) OpCode(apply_bif);
 	 ep->code[4] = (BeamInstr) bif_table[i].f;
 	 /* XXX: set func info for bifs */
-	 ((BeamInstr*)ep->code + 3)[-5] = (BeamInstr) BeamOp(op_i_func_info_IaaI);
+	 ep->fake_op_func_info_for_hipe[0] = (BeamInstr) BeamOp(op_i_func_info_IaaI);
      }
 
      return;
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index ac93b10d12..68b3350d7f 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -3408,6 +3408,7 @@ BIF_RETTYPE ports_0(BIF_ALIST_0)
     Eterm* dead_ports;
     int alive, dead;
     Uint32 next_ss;
+    int i;
 
     /* To get a consistent snapshot... 
      * We add alive ports from start of the buffer
@@ -3419,21 +3420,18 @@ BIF_RETTYPE ports_0(BIF_ALIST_0)
     erts_smp_atomic_set(&erts_dead_ports_ptr,
 			(erts_aint_t) (port_buf + erts_max_ports));
 
-    next_ss = erts_smp_atomic_inctest(&erts_ports_snapshot);
+    next_ss = erts_smp_atomic32_inctest(&erts_ports_snapshot);
 
-    if (erts_smp_atomic_read(&erts_ports_alive) > 0) {
-	erts_aint_t i;
-	for (i = erts_max_ports-1; i >= 0; i--) {
-	    Port* prt = &erts_port[i];
-	    erts_smp_port_state_lock(prt);
-	    if (!(prt->status & ERTS_PORT_SFLGS_DEAD)
-		&& prt->snapshot != next_ss) {
-		ASSERT(prt->snapshot == next_ss - 1);
-		*pp++ = prt->id;		
-		prt->snapshot = next_ss; /* Consumed by this snapshot */
-	    }
-	    erts_smp_port_state_unlock(prt);
+    for (i = erts_max_ports-1; i >= 0; i--) {
+	Port* prt = &erts_port[i];
+	erts_smp_port_state_lock(prt);
+	if (!(prt->status & ERTS_PORT_SFLGS_DEAD)
+	    && prt->snapshot != next_ss) {
+	    ASSERT(prt->snapshot == next_ss - 1);
+	    *pp++ = prt->id;		
+	    prt->snapshot = next_ss; /* Consumed by this snapshot */
 	}
+	erts_smp_port_state_unlock(prt);
     }
 
     dead_ports = (Eterm*)erts_smp_atomic_xchg(&erts_dead_ports_ptr,
diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c
index 694348e31d..fdc82c8b88 100644
--- a/erts/emulator/beam/erl_db_hash.c
+++ b/erts/emulator/beam/erl_db_hash.c
@@ -105,7 +105,7 @@
 #define NSEG_2   256 /* Size of second segment table */
 #define NSEG_INC 128 /* Number of segments to grow after that */
 
-#define SEGTAB(tb) ((struct segment**)erts_smp_atomic_read(&(tb)->segtab))
+#define SEGTAB(tb) ((struct segment**)erts_smp_atomic_read_acqb(&(tb)->segtab))
 #define NACTIVE(tb) ((int)erts_smp_atomic_read(&(tb)->nactive))
 #define NITEMS(tb) ((int)erts_smp_atomic_read(&(tb)->common.nitems))
 
@@ -122,8 +122,8 @@
 */
 static ERTS_INLINE Uint hash_to_ix(DbTableHash* tb, HashValue hval)
 {
-    Uint mask = erts_smp_atomic_read(&tb->szm);
-    Uint ix = hval & mask; 
+    Uint mask = erts_smp_atomic_read_acqb(&tb->szm);
+    Uint ix = hval & mask;
     if (ix >= erts_smp_atomic_read(&tb->nactive)) {
 	ix &= mask>>1;
 	ASSERT(ix < erts_smp_atomic_read(&tb->nactive));
@@ -668,6 +668,7 @@ int db_create_hash(Process *p, DbTable *tbl)
     else { /* coarse locking */
 	tb->locks = NULL;
     }
+    ERTS_THR_MEMORY_BARRIER;
 #endif /* ERST_SMP */
     return DB_ERROR_NONE;
 }
@@ -2349,7 +2350,7 @@ static int alloc_seg(DbTableHash *tb)
 	    struct ext_segment* eseg;
 	    eseg = (struct ext_segment*) SEGTAB(tb)[seg_ix-1];
 	    MY_ASSERT(eseg!=NULL && eseg->s.is_ext_segment);
-	    erts_smp_atomic_set(&tb->segtab, (erts_aint_t) eseg->segtab);
+	    erts_smp_atomic_set_relb(&tb->segtab, (erts_aint_t) eseg->segtab);
 	    tb->nsegs = eseg->nsegs;
 	}
 	ASSERT(seg_ix < tb->nsegs);
@@ -2421,7 +2422,7 @@ static int free_seg(DbTableHash *tb, int free_records)
 	    MY_ASSERT(newtop->s.is_ext_segment);
 	    if (newtop->prev_segtab != NULL) {
 		/* Time to use a smaller segtab */
-		erts_smp_atomic_set(&tb->segtab, (erts_aint_t)newtop->prev_segtab);
+		erts_smp_atomic_set_relb(&tb->segtab, (erts_aint_t)newtop->prev_segtab);
 		tb->nsegs = seg_ix;
 		ASSERT(tb->nsegs == EXTSEG(SEGTAB(tb))->nsegs);
 	    }
@@ -2438,7 +2439,7 @@ static int free_seg(DbTableHash *tb, int free_records)
     if (seg_ix > 0) {
 	if (seg_ix < tb->nsegs) SEGTAB(tb)[seg_ix] = NULL;
     } else {
-	erts_smp_atomic_set(&tb->segtab, (erts_aint_t)NULL);
+	erts_smp_atomic_set_relb(&tb->segtab, (erts_aint_t)NULL);
     }
 #endif
     tb->nslots -= SEGSZ;
@@ -2533,9 +2534,9 @@ static void grow(DbTableHash* tb, int nactive)
     }
     erts_smp_atomic_inc(&tb->nactive);
     if (from_ix == 0) {
-	erts_smp_atomic_set(&tb->szm, szm);
+	erts_smp_atomic_set_relb(&tb->szm, szm);
     }
-    erts_smp_atomic_set(&tb->is_resizing, 0);
+    erts_smp_atomic_set_relb(&tb->is_resizing, 0);
 
     /* Finally, let's split the bucket. We try to do it in a smart way
        to keep link order and avoid unnecessary updates of next-pointers */
@@ -2567,7 +2568,7 @@ static void grow(DbTableHash* tb, int nactive)
     return;
    
 abort:
-    erts_smp_atomic_set(&tb->is_resizing, 0);
+    erts_smp_atomic_set_relb(&tb->is_resizing, 0);
 }
 
 
@@ -2611,7 +2612,7 @@ static void shrink(DbTableHash* tb, int nactive)
 	    
 	    erts_smp_atomic_set(&tb->nactive, src_ix);
 	    if (dst_ix == 0) {
-		erts_smp_atomic_set(&tb->szm, low_szm);
+		erts_smp_atomic_set_relb(&tb->szm, low_szm);
 	    }
 	    WUNLOCK_HASH(lck);
 	    
@@ -2625,7 +2626,7 @@ static void shrink(DbTableHash* tb, int nactive)
 
     }
     /*else already done */
-    erts_smp_atomic_set(&tb->is_resizing, 0);
+    erts_smp_atomic_set_relb(&tb->is_resizing, 0);
 }
 
 
diff --git a/erts/emulator/beam/erl_db_tree.c b/erts/emulator/beam/erl_db_tree.c
index eb77d1281a..9a0ba3a418 100644
--- a/erts/emulator/beam/erl_db_tree.c
+++ b/erts/emulator/beam/erl_db_tree.c
@@ -111,7 +111,7 @@ static void release_stack(DbTableTree* tb, DbTreeStack* stack)
 {
     if (stack == &tb->static_stack) {
 	ASSERT(erts_smp_atomic_read(&tb->is_stack_busy) == 1);
-	erts_smp_atomic_set(&tb->is_stack_busy, 0);
+	erts_smp_atomic_set_relb(&tb->is_stack_busy, 0);
     }
     else {
 	erts_db_free(ERTS_ALC_T_DB_STK, (DbTable *) tb,
diff --git a/erts/emulator/beam/erl_drv_thread.c b/erts/emulator/beam/erl_drv_thread.c
index 39bbe9633b..dc578f6d2a 100644
--- a/erts/emulator/beam/erl_drv_thread.c
+++ b/erts/emulator/beam/erl_drv_thread.c
@@ -700,6 +700,13 @@ erl_drv_thread_join(ErlDrvTid tid, void **respp)
 extern int erts_darwin_main_thread_pipe[2];
 extern int erts_darwin_main_thread_result_pipe[2];
 
+int erl_drv_stolen_main_thread_join(ErlDrvTid tid, void **respp);
+int erl_drv_steal_main_thread(char *name,
+			      ErlDrvTid *dtid,
+			      void* (*func)(void*),
+			      void* arg,
+			      ErlDrvThreadOpts *opts);
+
 
 int
 erl_drv_stolen_main_thread_join(ErlDrvTid tid, void **respp)
diff --git a/erts/emulator/beam/erl_port_task.c b/erts/emulator/beam/erl_port_task.c
index 1b07024ca1..326021643f 100644
--- a/erts/emulator/beam/erl_port_task.c
+++ b/erts/emulator/beam/erl_port_task.c
@@ -658,8 +658,6 @@ erts_port_task_free_port(Port *pp)
 	   when scheduled out... */
 	ErtsPortTask *ptp = port_task_alloc();
 	erts_smp_port_state_lock(pp);
-	ASSERT(erts_smp_atomic_read(&erts_ports_alive) > 0);
-	erts_smp_atomic_dec(&erts_ports_alive);
 	pp->status &= ~ERTS_PORT_SFLG_CLOSING;
 	pp->status |= ERTS_PORT_SFLG_FREE_SCHEDULED;
 	erts_may_save_closed_port(pp);
@@ -681,7 +679,6 @@ erts_port_task_free_port(Port *pp)
 	    port_is_dequeued = 1;
 	}
 	erts_smp_port_state_lock(pp);
-	erts_smp_atomic_dec(&erts_ports_alive);
 	pp->status &= ~ERTS_PORT_SFLG_CLOSING;
 	pp->status |= ERTS_PORT_SFLG_FREE_SCHEDULED;
 	erts_may_save_closed_port(pp);
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 05172aaefa..2704359a8f 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -166,9 +166,8 @@ static struct {
 
 static struct {
     erts_smp_mtx_t update_mtx;
-    erts_smp_atomic32_t active_runqs;
+    erts_smp_atomic32_t no_runqs;
     int last_active_runqs;
-    erts_smp_atomic32_t used_runqs;
     int forced_check_balance;
     erts_smp_atomic32_t checking_balance;
     int halftime;
@@ -965,7 +964,7 @@ sched_spin_wait(ErtsSchedulerSleepInfo *ssi, int spincount)
     erts_aint32_t flgs;
 
     do {
-	flgs = erts_smp_atomic32_read(&ssi->flags);
+	flgs = erts_smp_atomic32_read_acqb(&ssi->flags);
 	if ((flgs & (ERTS_SSI_FLG_SLEEPING|ERTS_SSI_FLG_WAITING))
 	    != (ERTS_SSI_FLG_SLEEPING|ERTS_SSI_FLG_WAITING)) {
 	    break;
@@ -1114,7 +1113,7 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
     else {
 	erts_aint_t dt;
 
-	erts_smp_atomic32_set(&function_calls, 0);
+	erts_smp_atomic32_set_relb(&function_calls, 0);
 	*fcalls = 0;
 
 	sched_waiting_sys(esdp->no, rq);
@@ -1147,7 +1146,7 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 	    nonblockable_aux_work(esdp, ssi, aux_work);
 #endif
 
-	    flgs = erts_smp_atomic32_read(&ssi->flags);
+	    flgs = erts_smp_atomic32_read_acqb(&ssi->flags);
 	    if (!(flgs & ERTS_SSI_FLG_WAITING)) {
 		ASSERT(!(flgs & ERTS_SSI_FLG_SLEEPING));
 		goto sys_woken;
@@ -1333,6 +1332,76 @@ wake_all_schedulers(void)
     }
 }
 
+#define ERTS_NO_USED_RUNQS_SHIFT 16
+#define ERTS_NO_RUNQS_MASK 0xffff
+
+#if ERTS_MAX_NO_OF_SCHEDULERS > ERTS_NO_RUNQS_MASK
+#  error "Too large amount of schedulers allowed"
+#endif
+
+static ERTS_INLINE void
+init_no_runqs(int active, int used)
+{
+    erts_aint32_t no_runqs = (erts_aint32_t) (active & ERTS_NO_RUNQS_MASK);
+    no_runqs |= (erts_aint32_t) ((used & ERTS_NO_RUNQS_MASK) << ERTS_NO_USED_RUNQS_SHIFT);
+    erts_smp_atomic32_init(&balance_info.no_runqs, no_runqs);
+}
+
+static ERTS_INLINE void
+get_no_runqs(int *active, int *used)
+{
+    erts_aint32_t no_runqs = erts_smp_atomic32_read(&balance_info.no_runqs);
+    if (active)
+	*active = (int) (no_runqs & ERTS_NO_RUNQS_MASK);
+    if (used)
+	*used = (int) ((no_runqs >> ERTS_NO_USED_RUNQS_SHIFT) & ERTS_NO_RUNQS_MASK);
+}
+
+static ERTS_INLINE void
+set_no_used_runqs(int used)
+{
+    erts_aint32_t exp = erts_smp_atomic32_read(&balance_info.no_runqs);
+    while (1) {
+	erts_aint32_t act, new;
+	new = (used << ERTS_NO_USED_RUNQS_SHIFT) | (exp & ERTS_NO_RUNQS_MASK);
+	act = erts_smp_atomic32_cmpxchg(&balance_info.no_runqs, new, exp);
+	if (act == exp)
+	    break;
+	exp = act;
+    }
+}
+
+static ERTS_INLINE void
+set_no_active_runqs(int active)
+{
+    erts_aint32_t exp = erts_smp_atomic32_read(&balance_info.no_runqs);
+    while (1) {
+	erts_aint32_t act, new;
+	new = (exp & (ERTS_NO_RUNQS_MASK << ERTS_NO_USED_RUNQS_SHIFT)) | active;
+	act = erts_smp_atomic32_cmpxchg(&balance_info.no_runqs, new, exp);
+	if (act == exp)
+	    break;
+	exp = act;
+    }
+}
+
+static ERTS_INLINE int
+try_inc_no_active_runqs(int active)
+{
+    erts_aint32_t exp = erts_smp_atomic32_read(&balance_info.no_runqs);
+    if (((exp >> ERTS_NO_USED_RUNQS_SHIFT) & ERTS_NO_RUNQS_MASK) < active)
+	return 0;
+    if ((exp & ERTS_NO_RUNQS_MASK) + 1 == active) {
+	erts_aint32_t new, act;
+	new = (exp & ~ERTS_NO_RUNQS_MASK) | active;
+	act = erts_smp_atomic32_cmpxchg(&balance_info.no_runqs, new, exp);
+	if (act == exp)
+	    return 1;
+    }
+    return 0;
+}
+
+
 static ERTS_INLINE int
 chk_wake_sched(ErtsRunQueue *crq, int ix, int activate)
 {
@@ -1344,9 +1413,7 @@ chk_wake_sched(ErtsRunQueue *crq, int ix, int activate)
     iflgs = erts_smp_atomic32_read(&wrq->info_flags);
     if (!(iflgs & (ERTS_RUNQ_IFLG_SUSPENDED|ERTS_RUNQ_IFLG_NONEMPTY))) {
 	if (activate) {
-	    if (ix == erts_smp_atomic32_cmpxchg(&balance_info.active_runqs,
-						ix+1,
-						ix)) {
+	    if (try_inc_no_active_runqs(ix+1)) {
 		erts_smp_xrunq_lock(crq, wrq);
 		wrq->flags &= ~ERTS_RUNQ_FLG_INACTIVE;
 		erts_smp_xrunq_unlock(crq, wrq);
@@ -1363,8 +1430,9 @@ wake_scheduler_on_empty_runq(ErtsRunQueue *crq)
 {
     int ix = crq->ix;
     int stop_ix = ix;
-    int active_ix = erts_smp_atomic32_read(&balance_info.active_runqs);
-    int balance_ix = erts_smp_atomic32_read(&balance_info.used_runqs);
+    int active_ix, balance_ix;
+
+    get_no_runqs(&active_ix, &balance_ix);
 
     if (active_ix > balance_ix)
 	active_ix = balance_ix;
@@ -1416,7 +1484,7 @@ erts_sched_notify_check_cpu_bind(void)
     int ix;
     if (erts_common_run_queue) {
 	for (ix = 0; ix < erts_no_schedulers; ix++)
-	    erts_smp_atomic32_set(&ERTS_SCHEDULER_IX(ix)->chk_cpu_bind, 1);
+	    erts_smp_atomic32_set_relb(&ERTS_SCHEDULER_IX(ix)->chk_cpu_bind, 1);
 	wake_all_schedulers();
     }
     else {
@@ -1871,8 +1939,7 @@ try_steal_task(ErtsRunQueue *rq)
 
     ERTS_SMP_LC_CHK_RUNQ_LOCK(rq, rq_locked);
 
-    active_rqs = erts_smp_atomic32_read(&balance_info.active_runqs);
-    blnc_rqs = erts_smp_atomic32_read(&balance_info.used_runqs);
+    get_no_runqs(&active_rqs, &blnc_rqs);
 
     if (active_rqs > blnc_rqs)
 	active_rqs = blnc_rqs;
@@ -1883,7 +1950,7 @@ try_steal_task(ErtsRunQueue *rq)
 	if (active_rqs < blnc_rqs) {
 	    int no = blnc_rqs - active_rqs;
 	    int stop_ix = vix = active_rqs + rq->ix % no;
-	    while (erts_smp_atomic32_read(&no_empty_run_queues) < blnc_rqs) {
+	    while (erts_smp_atomic32_read_acqb(&no_empty_run_queues) < blnc_rqs) {
 		res = check_possible_steal_victim(rq, &rq_locked, vix);
 		if (res)
 		    goto done;
@@ -1898,7 +1965,7 @@ try_steal_task(ErtsRunQueue *rq)
 	vix = rq->ix;
 
 	/* ... then try to steal a job from another active queue... */
-	while (erts_smp_atomic32_read(&no_empty_run_queues) < blnc_rqs) {
+	while (erts_smp_atomic32_read_acqb(&no_empty_run_queues) < blnc_rqs) {
 	    vix++;
 	    if (vix >= active_rqs)
 		vix = 0;
@@ -1999,7 +2066,7 @@ check_balance(ErtsRunQueue *c_rq)
 	return;
     }
 
-    blnc_no_rqs = (int) erts_smp_atomic32_read(&balance_info.used_runqs);
+    get_no_runqs(NULL, &blnc_no_rqs);
     if (blnc_no_rqs == 1) {
 	c_rq->check_balance_reds = INT_MAX;
 	erts_smp_atomic32_set(&balance_info.checking_balance, 0);
@@ -2038,7 +2105,8 @@ check_balance(ErtsRunQueue *c_rq)
     forced = balance_info.forced_check_balance;
     balance_info.forced_check_balance = 0;
 
-    blnc_no_rqs = (int) erts_smp_atomic32_read(&balance_info.used_runqs);
+    get_no_runqs(&current_active, &blnc_no_rqs);
+
     if (blnc_no_rqs == 1) {
 	erts_smp_mtx_unlock(&balance_info.update_mtx);
 	erts_smp_runq_lock(c_rq);
@@ -2052,8 +2120,6 @@ check_balance(ErtsRunQueue *c_rq)
     if (balance_info.full_reds_history_index >= ERTS_FULL_REDS_HISTORY_SIZE)
 	balance_info.full_reds_history_index = 0;
 
-    current_active = erts_smp_atomic32_read(&balance_info.active_runqs);
-
     /* Read balance information for all run queues */
     for (qix = 0; qix < blnc_no_rqs; qix++) {
 	ErtsRunQueue *rq = ERTS_RUNQ_IX(qix);
@@ -2387,7 +2453,7 @@ erts_fprintf(stderr, "--------------------------------\n");
     }
 
     balance_info.last_active_runqs = active;
-    erts_smp_atomic32_set(&balance_info.active_runqs, active);
+    set_no_active_runqs(active);
 
     balance_info.halftime = 1;
     erts_smp_atomic32_set(&balance_info.checking_balance, 0);
@@ -2695,9 +2761,8 @@ erts_init_scheduling(int mrq, int no_schedulers, int no_schedulers_online)
     erts_smp_atomic32_init(&schdlr_sspnd.msb.ongoing, 0);
     erts_smp_atomic32_init(&schdlr_sspnd.active, no_schedulers);
     schdlr_sspnd.msb.procs = NULL;
-    erts_smp_atomic32_set(&balance_info.used_runqs,
-			  erts_common_run_queue ? 1 : no_schedulers_online);
-    erts_smp_atomic32_init(&balance_info.active_runqs, no_schedulers);
+    init_no_runqs(no_schedulers,
+		  erts_common_run_queue ? 1 : no_schedulers_online);
     balance_info.last_active_runqs = no_schedulers;
     erts_smp_mtx_init(&balance_info.update_mtx, "migration_info_update");
     balance_info.forced_check_balance = 0;
@@ -2939,7 +3004,7 @@ sched_spin_suspended(ErtsSchedulerSleepInfo *ssi, int spincount)
     erts_aint32_t flgs;
 
     do {
-	flgs = erts_smp_atomic32_read(&ssi->flags);
+	flgs = erts_smp_atomic32_read_acqb(&ssi->flags);
 	if ((flgs & (ERTS_SSI_FLG_SLEEPING
 		     | ERTS_SSI_FLG_WAITING
 		     | ERTS_SSI_FLG_SUSPENDED))
@@ -3068,7 +3133,7 @@ suspend_scheduler(ErtsSchedulerData *esdp)
 		wake = 0;
 	    }
 
-	    flgs = erts_smp_atomic32_read(&ssi->flags);
+	    flgs = erts_smp_atomic32_read_acqb(&ssi->flags);
 	    if (!(flgs & ERTS_SSI_FLG_SUSPENDED))
 		break;
 	    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
@@ -3292,7 +3357,7 @@ erts_set_schedulers_online(Process *p,
 			ErtsRunQueue *to_rq = ERTS_RUNQ_IX(ix % no);
 			evacuate_run_queue(from_rq, to_rq);
 		    }
-		    erts_smp_atomic32_set(&balance_info.used_runqs, no);
+		    set_no_used_runqs(no);
 		    erts_smp_mtx_unlock(&balance_info.update_mtx);
 		    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
 		}
@@ -3346,7 +3411,7 @@ erts_set_schedulers_online(Process *p,
 		    for (ix = erts_no_run_queues-1; ix >= no; ix--)
 			evacuate_run_queue(ERTS_RUNQ_IX(ix),
 					   ERTS_RUNQ_IX(ix % no));
-		    erts_smp_atomic32_set(&balance_info.used_runqs, no);
+		    set_no_used_runqs(no);
 		    erts_smp_mtx_unlock(&balance_info.update_mtx);
 		    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
 		    for (ix = no; ix < online; ix++) {
@@ -3443,7 +3508,7 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all)
 		else {
 		    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
 		    erts_smp_mtx_lock(&balance_info.update_mtx);
-		    erts_smp_atomic32_set(&balance_info.used_runqs, 1);
+		    set_no_used_runqs(1);
 		    for (ix = 0; ix < online; ix++) {
 			ErtsRunQueue *rq = ERTS_RUNQ_IX(ix);
 			erts_smp_runq_lock(rq);
@@ -3580,7 +3645,7 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all)
 		    evacuate_run_queue(ERTS_RUNQ_IX(ix),
 				       ERTS_RUNQ_IX(ix % online));
 
-		erts_smp_atomic32_set(&balance_info.used_runqs, online);
+		set_no_used_runqs(online);
 		/* Make sure that we balance soon... */
 		balance_info.forced_check_balance = 1;
 		erts_smp_runq_lock(ERTS_RUNQ_IX(0));
@@ -5131,7 +5196,7 @@ Process *schedule(Process *p, int calls)
 	esdp = erts_get_scheduler_data();
 	rq = erts_get_runq_current(esdp);
 	ASSERT(esdp);
-	fcalls = (int) erts_smp_atomic32_read(&function_calls);
+	fcalls = (int) erts_smp_atomic32_read_acqb(&function_calls);
 	actual_reds = reds = 0;
 	erts_smp_runq_lock(rq);
     } else {
@@ -5282,14 +5347,14 @@ Process *schedule(Process *p, int calls)
 			 | ERTS_RUNQ_FLG_CHK_CPU_BIND
 			 | ERTS_RUNQ_FLG_SUSPENDED)) {
 	    if ((rq->flags & ERTS_RUNQ_FLG_SUSPENDED)
-		|| (erts_smp_atomic32_read(&esdp->ssi->flags)
+		|| (erts_smp_atomic32_read_acqb(&esdp->ssi->flags)
 		    & ERTS_SSI_FLG_SUSPENDED)) {
 		ASSERT(erts_smp_atomic32_read(&esdp->ssi->flags)
 		       & ERTS_SSI_FLG_SUSPENDED);
 		suspend_scheduler(esdp);
 	    }
 	    if ((rq->flags & ERTS_RUNQ_FLG_CHK_CPU_BIND)
-		|| erts_smp_atomic32_read(&esdp->chk_cpu_bind)) {
+		|| erts_smp_atomic32_read_acqb(&esdp->chk_cpu_bind)) {
 		erts_sched_check_cpu_bind(esdp);
 	    }
 	}
@@ -5340,7 +5405,7 @@ Process *schedule(Process *p, int calls)
 	    if (rq->flags & (ERTS_RUNQ_FLG_SHARED_RUNQ
 			     | ERTS_RUNQ_FLG_SUSPENDED)) {
 		if ((rq->flags & ERTS_RUNQ_FLG_SUSPENDED)
-		    || (erts_smp_atomic32_read(&esdp->ssi->flags)
+		    || (erts_smp_atomic32_read_acqb(&esdp->ssi->flags)
 			& ERTS_SSI_FLG_SUSPENDED)) {
 		    ASSERT(erts_smp_atomic32_read(&esdp->ssi->flags)
 			   & ERTS_SSI_FLG_SUSPENDED);
@@ -5384,7 +5449,7 @@ Process *schedule(Process *p, int calls)
 	     * Schedule system-level activities.
 	     */
 
-	    erts_smp_atomic32_set(&function_calls, 0);
+	    erts_smp_atomic32_set_relb(&function_calls, 0);
 	    fcalls = 0;
 
 	    ASSERT(!erts_port_task_have_outstanding_io_tasks());
@@ -5426,7 +5491,7 @@ Process *schedule(Process *p, int calls)
 			if (erts_common_run_queue->waiting)
 			    wake_scheduler(erts_common_run_queue, 0, 1);
 		    }
-		    else if (erts_smp_atomic32_read(&no_empty_run_queues) != 0) {
+		    else if (erts_smp_atomic32_read_acqb(&no_empty_run_queues) != 0) {
 			wake_scheduler_on_empty_runq(rq);
 			rq->wakeup_other = 0;
 		    }
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 30b0a60611..499bdd77ba 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -183,7 +183,7 @@ struct port {
 				    process to get (line oriented I/O)*/
     Uint32 status;		 /* Status and type flags */
     int control_flags;		 /* Flags for port_control()  */
-    Uint32 snapshot;             /* Next snapshot that port should be part of */
+    erts_aint32_t snapshot;      /* Next snapshot that port should be part of */
     struct reg_proc *reg;
     ErlDrvPDL port_data_lock;
 
@@ -527,11 +527,10 @@ union erl_off_heap_ptr {
 
 /* arrays that get malloced at startup */
 extern Port* erts_port;
-extern erts_smp_atomic_t erts_ports_alive;
 
 extern Uint erts_max_ports;
 extern Uint erts_port_tab_index_mask;
-extern erts_smp_atomic_t erts_ports_snapshot;
+extern erts_smp_atomic32_t erts_ports_snapshot;
 extern erts_smp_atomic_t erts_dead_ports_ptr;
 
 ERTS_GLB_INLINE void erts_may_save_closed_port(Port *prt);
@@ -541,12 +540,12 @@ ERTS_GLB_INLINE void erts_may_save_closed_port(Port *prt);
 ERTS_GLB_INLINE void erts_may_save_closed_port(Port *prt)
 {
     ERTS_SMP_LC_ASSERT(erts_smp_lc_spinlock_is_locked(&prt->state_lck));
-    if (prt->snapshot != erts_smp_atomic_read(&erts_ports_snapshot)) {
+    if (prt->snapshot != erts_smp_atomic32_read_acqb(&erts_ports_snapshot)) {
 	/* Dead ports are added from the end of the snapshot buffer */
 	Eterm* tombstone = (Eterm*) erts_smp_atomic_addtest(&erts_dead_ports_ptr,
 							    -(erts_aint_t)sizeof(Eterm));
 	ASSERT(tombstone+1 != NULL);
-	ASSERT(prt->snapshot == (Uint32) erts_smp_atomic_read(&erts_ports_snapshot) - 1);
+	ASSERT(prt->snapshot == erts_smp_atomic32_read(&erts_ports_snapshot) - 1);
 	*tombstone = prt->id;
     }
     /*else no ongoing snapshot or port was already included or created after snapshot */
diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index d9df90fe7d..df5f8b22a3 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -56,7 +56,6 @@ static erts_smp_tsd_key_t driver_list_last_error_key;  /* Save last DDLL error o
 							  per thread basis (for BC interfaces) */
 
 Port*      erts_port; /* The port table */
-erts_smp_atomic_t erts_ports_alive;
 erts_smp_atomic_t erts_bytes_out;	/* No bytes sent out of the system */
 erts_smp_atomic_t erts_bytes_in;	/* No bytes gotten into the system */
 
@@ -193,7 +192,7 @@ typedef struct line_buf_context {
 static erts_smp_spinlock_t get_free_port_lck;
 static Uint last_port_num;
 static Uint port_num_mask;
-erts_smp_atomic_t erts_ports_snapshot; /* Identifies the _next_ snapshot (not the ongoing) */
+erts_smp_atomic32_t erts_ports_snapshot; /* Identifies the _next_ snapshot (not the ongoing) */
 
 
 static ERTS_INLINE void
@@ -424,10 +423,9 @@ setup_port(Port* prt, Eterm pid, erts_driver_t *driver,
     new_name = (char*) erts_alloc(ERTS_ALC_T_PORT_NAME, sys_strlen(name)+1);
     sys_strcpy(new_name, name);
     erts_smp_runq_lock(runq);
-    erts_smp_atomic_inc(&erts_ports_alive);
     erts_smp_port_state_lock(prt);    
     prt->status = ERTS_PORT_SFLG_CONNECTED | xstatus;
-    prt->snapshot = (Uint32) erts_smp_atomic_read(&erts_ports_snapshot);    
+    prt->snapshot = erts_smp_atomic32_read(&erts_ports_snapshot);    
     old_name = prt->name;
     prt->name = new_name;
 #ifdef ERTS_SMP
@@ -1281,7 +1279,6 @@ void init_io(void)
 
     erts_smp_atomic_init(&erts_bytes_out, 0);
     erts_smp_atomic_init(&erts_bytes_in, 0);
-    erts_smp_atomic_init(&erts_ports_alive, 0);
 
     for (i = 0; i < erts_max_ports; i++) {
 	erts_port_task_init_sched(&erts_port[i].sched);
@@ -1303,7 +1300,7 @@ void init_io(void)
 	erts_port[i].port_data_lock = NULL;
     }
 
-    erts_smp_atomic_init(&erts_ports_snapshot, (erts_aint_t) 0);
+    erts_smp_atomic32_init(&erts_ports_snapshot, (erts_aint32_t) 0);
     last_port_num = 0;
     erts_smp_spinlock_init(&get_free_port_lck, "get_free_port");
 
diff --git a/erts/emulator/beam/safe_hash.c b/erts/emulator/beam/safe_hash.c
index 21d6ce9304..3e9243c77d 100644
--- a/erts/emulator/beam/safe_hash.c
+++ b/erts/emulator/beam/safe_hash.c
@@ -99,7 +99,7 @@ static void rehash(SafeHash* h, int grow_limit)
 	erts_free(h->type, (void *) old_tab);
     }
     /*else already done */
-    erts_smp_atomic_set(&h->is_rehashing, 0);
+    erts_smp_atomic_set_relb(&h->is_rehashing, 0);
 }