Merge branch 'master' into sverk/master/halt-INT_MIN

1 files changed, 870 insertions, 654 deletions

diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 12687deaeb..d976df1d7e 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -58,11 +58,7 @@
 
 #define ERTS_PROC_MIN_CONTEXT_SWITCH_REDS_COST (CONTEXT_REDS/10)
 
-#ifndef ERTS_SCHED_MIN_SPIN
 #define ERTS_SCHED_SPIN_UNTIL_YIELD 100
-#else
-#define ERTS_SCHED_SPIN_UNTIL_YIELD 1
-#endif
 
 #define ERTS_SCHED_SYS_SLEEP_SPINCOUNT_VERY_LONG 40
 #define ERTS_SCHED_AUX_WORK_SLEEP_SPINCOUNT_FACT_VERY_LONG 1000
@@ -119,7 +115,7 @@
 #define RUNQ_SET_RQ(X, RQ) erts_smp_atomic_set_nob((X), (erts_aint_t) (RQ))
 
 #ifdef DEBUG
-#  if defined(ARCH_64) && !HALFWORD_HEAP
+#  if defined(ARCH_64)
 #    define ERTS_DBG_SET_INVALID_RUNQP(RQP, N) \
     (RUNQ_SET_RQ((RQP), (0xdeadbeefdead0003LL | ((N) << 4)))
 #  define ERTS_DBG_VERIFY_VALID_RUNQP(RQP) \
@@ -152,18 +148,14 @@ extern BeamInstr beam_apply[];
 extern BeamInstr beam_exit[];
 extern BeamInstr beam_continue_exit[];
 
-#ifdef __OSE__
-/* Eager check I/O not supported on OSE yet. */
-int erts_eager_check_io = 0;
-#else
-int erts_eager_check_io = 1;
-#endif
-int erts_sched_compact_load;
-int erts_sched_balance_util = 0;
-Uint erts_no_schedulers;
+int ERTS_WRITE_UNLIKELY(erts_default_spo_flags) = 0;
+int ERTS_WRITE_UNLIKELY(erts_eager_check_io) = 1;
+int ERTS_WRITE_UNLIKELY(erts_sched_compact_load);
+int ERTS_WRITE_UNLIKELY(erts_sched_balance_util) = 0;
+Uint ERTS_WRITE_UNLIKELY(erts_no_schedulers);
 #ifdef ERTS_DIRTY_SCHEDULERS
-Uint erts_no_dirty_cpu_schedulers;
-Uint erts_no_dirty_io_schedulers;
+Uint ERTS_WRITE_UNLIKELY(erts_no_dirty_cpu_schedulers);
+Uint ERTS_WRITE_UNLIKELY(erts_no_dirty_io_schedulers);
 #endif
 
 static char *erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_NO_FLAGS] = {0};
@@ -303,7 +295,7 @@ do {							\
 erts_sched_stat_t erts_sched_stat;
 
 #ifdef USE_THREADS
-static erts_tsd_key_t sched_data_key;
+static erts_tsd_key_t ERTS_WRITE_UNLIKELY(sched_data_key);
 #endif
 
 static erts_smp_atomic32_t function_calls;
@@ -343,16 +335,16 @@ static ErtsAlignedSchedulerSleepInfo *aligned_dirty_io_sched_sleep_info;
 
 static Uint last_reductions;
 static Uint last_exact_reductions;
-Uint erts_default_process_flags;
-Eterm erts_system_monitor;
-Eterm erts_system_monitor_long_gc;
-Uint erts_system_monitor_long_schedule;
-Eterm erts_system_monitor_large_heap;
+Eterm ERTS_WRITE_UNLIKELY(erts_system_monitor);
+Eterm ERTS_WRITE_UNLIKELY(erts_system_monitor_long_gc);
+Uint ERTS_WRITE_UNLIKELY(erts_system_monitor_long_schedule);
+Eterm ERTS_WRITE_UNLIKELY(erts_system_monitor_large_heap);
 struct erts_system_monitor_flags_t erts_system_monitor_flags;
 
 /* system performance monitor */
 Eterm erts_system_profile;
 struct erts_system_profile_flags_t erts_system_profile_flags;
+int erts_system_profile_ts_type = ERTS_TRACE_FLG_NOW_TIMESTAMP;
 
 #if ERTS_MAX_PROCESSES > 0x7fffffff
 #error "Need to store process_count in another type"
@@ -360,7 +352,8 @@ struct erts_system_profile_flags_t erts_system_profile_flags;
 
 typedef enum {
     ERTS_PSTT_GC,	/* Garbage Collect */
-    ERTS_PSTT_CPC	/* Check Process Code */
+    ERTS_PSTT_CPC,	/* Check Process Code */
+    ERTS_PSTT_COHMQ     /* Change off heap message queue */
 } ErtsProcSysTaskType;
 
 #define ERTS_MAX_PROC_SYS_TASK_ARGS 2
@@ -506,9 +499,6 @@ dbg_chk_aux_work_val(erts_aint32_t value)
 #if HAVE_ERTS_MSEG
     valid |= ERTS_SSI_AUX_WORK_MSEG_CACHE_CHECK;
 #endif
-#ifdef ERTS_SMP_SCHEDULERS_NEED_TO_CHECK_CHILDREN
-    valid |= ERTS_SSI_AUX_WORK_CHECK_CHILDREN;
-#endif
 #ifdef ERTS_SSI_AUX_WORK_REAP_PORTS
     valid |= ERTS_SSI_AUX_WORK_REAP_PORTS;
 #endif
@@ -595,8 +585,6 @@ erts_pre_init_process(void)
 	= "MISC_THR_PRGR";
     erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_MISC_IX]
 	= "MISC";
-    erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_CHECK_CHILDREN_IX]
-	= "CHECK_CHILDREN";
     erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_SET_TMO_IX]
 	= "SET_TMO";
     erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_MSEG_CACHE_CHECK_IX]
@@ -684,7 +672,6 @@ erts_init_process(int ncpu, int proc_tab_size, int legacy_proc_tab)
 
     last_reductions = 0;
     last_exact_reductions = 0;
-    erts_default_process_flags = 0;
 }
 
 void
@@ -954,6 +941,12 @@ sched_wall_time_change(ErtsSchedulerData *esdp, int working)
 	    }
 	}
     }
+    if (!working) {
+        ERTS_MSACC_SET_STATE_M_X(ERTS_MSACC_STATE_BUSY_WAIT);
+    } else {
+        ERTS_MSACC_SET_STATE_M_X(ERTS_MSACC_STATE_OTHER);
+    }
+
 }
 
 typedef struct {
@@ -966,25 +959,10 @@ typedef struct {
     erts_smp_atomic32_t refc;
 } ErtsSchedWallTimeReq;
 
-#if !HALFWORD_HEAP
 ERTS_SCHED_PREF_QUICK_ALLOC_IMPL(swtreq,
-				 ErtsSchedWallTimeReq,
-				 5,
-				 ERTS_ALC_T_SCHED_WTIME_REQ)
-#else
-static ERTS_INLINE ErtsSchedWallTimeReq *
-swtreq_alloc(void)
-{
-    return erts_alloc(ERTS_ALC_T_SCHED_WTIME_REQ,
-		      sizeof(ErtsSchedWallTimeReq));
-}
-
-static ERTS_INLINE void
-swtreq_free(ErtsSchedWallTimeReq *ptr)
-{
-    erts_free(ERTS_ALC_T_SCHED_WTIME_REQ, ptr);
-}
-#endif
+                                 ErtsSchedWallTimeReq,
+                                 5,
+                                 ERTS_ALC_T_SCHED_WTIME_REQ)
 
 static void
 reply_sched_wall_time(void *vswtrp)
@@ -1001,7 +979,7 @@ reply_sched_wall_time(void *vswtrp)
     Eterm **hpp;
     Uint sz, *szp;
     ErlOffHeap *ohp = NULL;
-    ErlHeapFragment *bp = NULL;
+    ErtsMessage *mp = NULL;
 
     ASSERT(esdp);
 #ifdef ERTS_DIRTY_SCHEDULERS
@@ -1057,12 +1035,12 @@ reply_sched_wall_time(void *vswtrp)
 	if (hpp)
 	    break;
 
-	hp = erts_alloc_message_heap(sz, &bp, &ohp, rp, &rp_locks);
+	mp = erts_alloc_message_heap(rp, &rp_locks, sz, &hp, &ohp);
 	szp = NULL;
 	hpp = &hp;
     }
 
-    erts_queue_message(rp, &rp_locks, bp, msg, NIL);
+    erts_queue_message(rp, &rp_locks, mp, msg, NIL);
 
     if (swtrp->req_sched == esdp->no)
 	rp_locks &= ~ERTS_PROC_LOCK_MAIN;
@@ -1724,15 +1702,17 @@ handle_delayed_dealloc(ErtsAuxWorkData *awdp, erts_aint32_t aux_work, int waitin
     int need_thr_progress = 0;
     ErtsThrPrgrVal wakeup = ERTS_THR_PRGR_INVALID;
     int more_work = 0;
-
+    ERTS_MSACC_PUSH_STATE_M_X();
 #ifdef ERTS_DIRTY_SCHEDULERS
     ASSERT(!awdp->esdp || !ERTS_SCHEDULER_IS_DIRTY(awdp->esdp));
 #endif
     unset_aux_work_flags(ssi, ERTS_SSI_AUX_WORK_DD);
+    ERTS_MSACC_SET_STATE_CACHED_M_X(ERTS_MSACC_STATE_ALLOC);
     erts_alloc_scheduler_handle_delayed_dealloc((void *) awdp->esdp,
 						&need_thr_progress,
 						&wakeup,
 						&more_work);
+    ERTS_MSACC_POP_STATE_M_X();
     if (more_work) {
 	if (set_aux_work_flags(ssi, ERTS_SSI_AUX_WORK_DD)
 	    & ERTS_SSI_AUX_WORK_DD_THR_PRGR) {
@@ -2119,34 +2099,6 @@ erts_debug_wait_completed(Process *c_p, int flags)
 }
 
 
-#ifdef ERTS_SMP_SCHEDULERS_NEED_TO_CHECK_CHILDREN
-void
-erts_smp_notify_check_children_needed(void)
-{
-    int i;
-    for (i = 0; i < erts_no_schedulers; i++)
-	set_aux_work_flags_wakeup_nob(ERTS_SCHED_SLEEP_INFO_IX(i),
-				      ERTS_SSI_AUX_WORK_CHECK_CHILDREN);
-#ifdef ERTS_DIRTY_SCHEDULERS
-    for (i = 0; i < erts_no_dirty_cpu_schedulers; i++)
-	set_aux_work_flags_wakeup_nob(ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(i),
-				      ERTS_SSI_AUX_WORK_CHECK_CHILDREN);
-    for (i = 0; i < erts_no_dirty_io_schedulers; i++)
-	set_aux_work_flags_wakeup_nob(ERTS_DIRTY_IO_SCHED_SLEEP_INFO_IX(i),
-				      ERTS_SSI_AUX_WORK_CHECK_CHILDREN);
-#endif
-}
-
-static ERTS_INLINE erts_aint32_t
-handle_check_children(ErtsAuxWorkData *awdp, erts_aint32_t aux_work, int waiting)
-{
-    unset_aux_work_flags(awdp->ssi, ERTS_SSI_AUX_WORK_CHECK_CHILDREN);
-    erts_check_children();
-    return aux_work & ~ERTS_SSI_AUX_WORK_CHECK_CHILDREN;
-}
-
-#endif
-
 static void
 notify_reap_ports_relb(void)
 {
@@ -2232,13 +2184,17 @@ handle_aux_work(ErtsAuxWorkData *awdp, erts_aint32_t orig_aux_work, int waiting)
 	ERTS_DBG_CHK_AUX_WORK_VAL(aux_work); \
 	if (!(aux_work & ~ignore)) { \
 	    ERTS_DBG_CHK_AUX_WORK_VAL(aux_work); \
+            ERTS_MSACC_UPDATE_CACHE();       \
+            ERTS_MSACC_POP_STATE_M();              \
 	    return aux_work; \
 	} \
     }
 
     erts_aint32_t aux_work = orig_aux_work;
     erts_aint32_t ignore = 0;
+    ERTS_MSACC_PUSH_AND_SET_STATE_M(ERTS_MSACC_STATE_AUX);
 
+    ASSERT(!awdp->esdp || !ERTS_SCHEDULER_IS_DIRTY(awdp->esdp));
 #ifdef ERTS_SMP
     haw_thr_prgr_current_reset(awdp);
 #endif
@@ -2300,10 +2256,6 @@ handle_aux_work(ErtsAuxWorkData *awdp, erts_aint32_t orig_aux_work, int waiting)
     HANDLE_AUX_WORK(ERTS_SSI_AUX_WORK_MISC,
 		    handle_misc_aux_work);
 
-#ifdef ERTS_SMP_SCHEDULERS_NEED_TO_CHECK_CHILDREN
-    HANDLE_AUX_WORK(ERTS_SSI_AUX_WORK_CHECK_CHILDREN,
-		    handle_check_children);
-#endif
 
     HANDLE_AUX_WORK(ERTS_SSI_AUX_WORK_SET_TMO,
 		    handle_setup_aux_work_timer);
@@ -2331,6 +2283,8 @@ handle_aux_work(ErtsAuxWorkData *awdp, erts_aint32_t orig_aux_work, int waiting)
 	haw_thr_prgr_current_check_progress(awdp);
 #endif
 
+    ERTS_MSACC_UPDATE_CACHE();
+    ERTS_MSACC_POP_STATE_M();
     return aux_work;
 
 #undef HANDLE_AUX_WORK
@@ -2531,19 +2485,10 @@ try_set_sys_scheduling(void)
 #endif
 
 static ERTS_INLINE int
-prepare_for_sys_schedule(ErtsSchedulerData *esdp, int non_blocking)
+prepare_for_sys_schedule(int non_blocking)
 {
     if (non_blocking && erts_eager_check_io) {
 #ifdef ERTS_SMP
-#ifdef ERTS_SCHED_ONLY_POLL_SCHED_1
-	if (esdp->no != 1) {
-	    /* If we are not scheduler 1 and ERTS_SCHED_ONLY_POLL_SCHED_1 is used
-	       then we make sure to wake scheduler 1 */
-	    ErtsRunQueue *rq = ERTS_RUNQ_IX(0);
-	    wake_scheduler(rq);
-	    return 0;
-	}
-#endif
 	return try_set_sys_scheduling();
 #else
 	return 1;
@@ -2553,16 +2498,6 @@ prepare_for_sys_schedule(ErtsSchedulerData *esdp, int non_blocking)
 #ifdef ERTS_SMP
 	while (!erts_port_task_have_outstanding_io_tasks()
 	       && try_set_sys_scheduling()) {
-#ifdef ERTS_SCHED_ONLY_POLL_SCHED_1
-	    if (esdp->no != 1) {
-		/* If we are not scheduler 1 and ERTS_SCHED_ONLY_POLL_SCHED_1 is used
-		   then we make sure to wake scheduler 1 */
-		ErtsRunQueue *rq = ERTS_RUNQ_IX(0);
-		clear_sys_scheduling();
-		wake_scheduler(rq);
-		return 0;
-	    }
-#endif
 	    if (!erts_port_task_have_outstanding_io_tasks())
 		return 1;
 	    clear_sys_scheduling();
@@ -2857,6 +2792,8 @@ aux_thread(void *unused)
 
     ssi->event = erts_tse_fetch();
 
+    erts_msacc_init_thread("aux", 1, 1);
+
     callbacks.arg = (void *) ssi;
     callbacks.wakeup = thr_prgr_wakeup;
     callbacks.prepare_wait = thr_prgr_prep_wait;
@@ -2867,6 +2804,7 @@ aux_thread(void *unused)
     init_aux_work_data(awdp, NULL, NULL);
     awdp->ssi = ssi;
 
+
     sched_prep_spin_wait(ssi);
 
     while (1) {
@@ -2886,8 +2824,6 @@ aux_thread(void *unused)
 		erts_thr_progress_active(NULL, thr_prgr_active = 0);
 	    erts_thr_progress_prepare_wait(NULL);
 
-	    ERTS_SCHED_FAIR_YIELD();
-
 	    flgs = sched_spin_wait(ssi, 0);
 
 	    if (flgs & ERTS_SSI_FLG_SLEEPING) {
@@ -2922,6 +2858,9 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 #ifdef ERTS_SMP
     int thr_prgr_active = 1;
     erts_aint32_t flgs;
+#endif
+    ERTS_MSACC_PUSH_STATE_M();
+#ifdef ERTS_SMP
 
     ERTS_SMP_LC_ASSERT(erts_smp_lc_runq_is_locked(rq));
 
@@ -2955,7 +2894,7 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
      * be waiting in erl_sys_schedule()
      */
 
-    if (ERTS_SCHEDULER_IS_DIRTY(esdp) || !prepare_for_sys_schedule(esdp, 0)) {
+    if (ERTS_SCHEDULER_IS_DIRTY(esdp) || !prepare_for_sys_schedule(0)) {
 
 	sched_waiting(esdp->no, rq);
 
@@ -2969,17 +2908,17 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 	    sched_wall_time_change(esdp, thr_prgr_active);
 
 	while (1) {
-	    ErtsMonotonicTime current_time;
+	    ErtsMonotonicTime current_time = 0;
 
 	    aux_work = erts_atomic32_read_acqb(&ssi->aux_work);
-	    if (aux_work) {
-		if (!ERTS_SCHEDULER_IS_DIRTY(esdp) && !thr_prgr_active) {
+	    if (aux_work && !ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+		if (!thr_prgr_active) {
 		    erts_thr_progress_active(esdp, thr_prgr_active = 1);
 		    sched_wall_time_change(esdp, 1);
 		}
 		aux_work = handle_aux_work(&esdp->aux_work_data, aux_work, 1);
-		if (aux_work && !ERTS_SCHEDULER_IS_DIRTY(esdp)
-		    && erts_thr_progress_update(esdp))
+                ERTS_MSACC_UPDATE_CACHE();
+		if (aux_work && erts_thr_progress_update(esdp))
 		    erts_thr_progress_leader_update(esdp);
 	    }
 
@@ -3020,8 +2959,6 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 			erts_thr_progress_prepare_wait(esdp);
 		    }
 
-		    ERTS_SCHED_FAIR_YIELD();
-
 		    flgs = sched_spin_wait(ssi, spincount);
 		    if (flgs & ERTS_SSI_FLG_SLEEPING) {
 			ASSERT(flgs & ERTS_SSI_FLG_WAITING);
@@ -3042,7 +2979,9 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 								     - 1) + 1;
 				} else
 				    timeout = -1;
+                                ERTS_MSACC_SET_STATE_CACHED_M(ERTS_MSACC_STATE_SLEEP);
 				res = erts_tse_twait(ssi->event, timeout);
+                                ERTS_MSACC_POP_STATE_M();
 				current_time = ERTS_SCHEDULER_IS_DIRTY(esdp) ? 0 :
 				    erts_get_monotonic_time(esdp);
 			    } while (res == EINTR);
@@ -3092,13 +3031,8 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 #ifdef ERTS_DIRTY_SCHEDULERS
 	ASSERT(!ERTS_SCHEDULER_IS_DIRTY(esdp));
 #endif
-
-#ifdef ERTS_SCHED_ONLY_POLL_SCHED_1
-	ASSERT(esdp->no == 1);
-#endif
 	sched_waiting_sys(esdp->no, rq);
 
-
 	erts_smp_runq_unlock(rq);
 
 	ASSERT(working);
@@ -3116,9 +3050,13 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 	    if (working)
 		sched_wall_time_change(esdp, working = 0);
 
+	    ERTS_MSACC_SET_STATE_CACHED_M(ERTS_MSACC_STATE_CHECK_IO);
+
 	    ASSERT(!erts_port_task_have_outstanding_io_tasks());
 	    erl_sys_schedule(1); /* Might give us something to do */
 
+	    ERTS_MSACC_POP_STATE_M();
+
 	    if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
 		current_time = erts_get_monotonic_time(esdp);
 		if (current_time >= erts_next_timeout_time(esdp->next_tmo_ref))
@@ -3131,25 +3069,23 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 #endif
 
 	    aux_work = erts_atomic32_read_acqb(&ssi->aux_work);
-	    if (aux_work) {
-		if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
-		    if (!working)
-			sched_wall_time_change(esdp, working = 1);
+	    if (aux_work && !ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+		if (!working)
+		    sched_wall_time_change(esdp, working = 1);
 #ifdef ERTS_SMP
-		    if (!thr_prgr_active)
-			erts_thr_progress_active(esdp, thr_prgr_active = 1);
+		if (!thr_prgr_active)
+		    erts_thr_progress_active(esdp, thr_prgr_active = 1);
 #endif
-		}
 		aux_work = handle_aux_work(&esdp->aux_work_data, aux_work, 1);
+                ERTS_MSACC_UPDATE_CACHE();
 #ifdef ERTS_SMP
-		if (!ERTS_SCHEDULER_IS_DIRTY(esdp) && aux_work &&
-		    erts_thr_progress_update(esdp))
+		if (aux_work && erts_thr_progress_update(esdp))
 		    erts_thr_progress_leader_update(esdp);
 #endif
 	    }
 
 #ifndef ERTS_SMP
-	    if (rq->len != 0 || rq->misc.start)
+	    if (erts_smp_atomic32_read_dirty(&rq->len) != 0 || rq->misc.start)
 		goto sys_woken;
 #else
 	    flgs = erts_smp_atomic32_read_acqb(&ssi->flags);
@@ -3168,7 +3104,7 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 		 * Got to check that we still got I/O tasks; otherwise
 		 * we have to continue checking for I/O...
 		 */
-		if (!prepare_for_sys_schedule(esdp, 0)) {
+		if (!prepare_for_sys_schedule(0)) {
 		    spincount *= ERTS_SCHED_TSE_SLEEP_SPINCOUNT_FACT;
 		    goto tse_wait;
 		}
@@ -3190,7 +3126,7 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 	     * Got to check that we still got I/O tasks; otherwise
 	     * we have to wait in erl_sys_schedule() after all...
 	     */
-	    if (!prepare_for_sys_schedule(esdp, 0)) {
+	    if (!prepare_for_sys_schedule(0)) {
 		/*
 		 * Not allowed to wait in erl_sys_schedule;
 		 * do tse wait instead...
@@ -3239,8 +3175,12 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 
 	ASSERT(!erts_port_task_have_outstanding_io_tasks());
 
+	ERTS_MSACC_SET_STATE_CACHED_M(ERTS_MSACC_STATE_CHECK_IO);
+
 	erl_sys_schedule(0);
 
+	ERTS_MSACC_POP_STATE_M();
+
 	if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
 	    ErtsMonotonicTime current_time = erts_get_monotonic_time(esdp);
 	    if (current_time >= erts_next_timeout_time(esdp->next_tmo_ref))
@@ -3248,7 +3188,7 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 	}
 
 #ifndef ERTS_SMP
-	if (rq->len == 0 && !rq->misc.start)
+	if (erts_smp_atomic32_read_dirty(&rq->len) == 0 && !rq->misc.start)
 	    goto sys_aux_work;
     sys_woken:
 #else
@@ -3635,6 +3575,13 @@ check_requeue_process(ErtsRunQueue *rq, int prio_q)
     return 0;
 }
 
+static ERTS_INLINE void
+free_proxy_proc(Process *proxy)
+{
+    ASSERT(erts_smp_atomic32_read_nob(&proxy->state) & ERTS_PSFLG_PROXY);
+    erts_free(ERTS_ALC_T_PROC, proxy);
+}
+
 #ifdef ERTS_SMP
 
 static ErtsRunQueue *
@@ -3949,9 +3896,6 @@ evacuate_run_queue(ErtsRunQueue *rq,
 	erts_aint32_t state;
 	Process *proc;
 	int notify = 0;
-#ifdef ERTS_DIRTY_SCHEDULERS
-	int requeue;
-#endif
 	to_rq = NULL;
 
 #ifdef ERTS_DIRTY_SCHEDULERS
@@ -3966,49 +3910,94 @@ evacuate_run_queue(ErtsRunQueue *rq,
 
 	proc = dequeue_process(rq, prio_q, &state);
 	while (proc) {
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    requeue = 1;
+	    Process *real_proc;
+	    int prio;
+	    erts_aint32_t max_qbit, qbit, real_state;
+
+	    prio = ERTS_PSFLGS_GET_PRQ_PRIO(state);
+	    qbit = ((erts_aint32_t) 1) << prio;
+
+	    if (!(state & ERTS_PSFLG_PROXY)) {
+		real_proc = proc;
+		real_state = state;
+	    }
+	    else {
+		real_proc = erts_proc_lookup_raw(proc->common.id);
+		if (!real_proc) {
+		    free_proxy_proc(proc);
+		    goto handle_next_proc;
+		}
+		real_state =  erts_smp_atomic32_read_acqb(&real_proc->state);
+	    }
+
+	    max_qbit = (state >> ERTS_PSFLGS_IN_PRQ_MASK_OFFSET);
+	    max_qbit &= ERTS_PSFLGS_QMASK;
+	    max_qbit |= 1 << ERTS_PSFLGS_QMASK_BITS;
+	    max_qbit &= -max_qbit;
+
+	    if (qbit > max_qbit) {
+		/* Process already queued with higher prio; drop it... */
+		if (real_proc != proc)
+		    free_proxy_proc(proc);
+		else {
+		    erts_aint32_t clr_bits;
+#ifdef DEBUG
+		    erts_aint32_t old;
 #endif
-	    if (ERTS_PSFLG_BOUND & state) {
-		/* Bound processes get stuck here... */
-		proc->next = NULL;
-		if (sbpp->last)
-		    sbpp->last->next = proc;
-		else
-		    sbpp->first = proc;
-		sbpp->last = proc;
-#ifdef ERTS_DIRTY_SCHEDULERS
-		requeue = 0;
+
+		    clr_bits = ERTS_PSFLG_IN_RUNQ;
+		    clr_bits |= qbit << ERTS_PSFLGS_IN_PRQ_MASK_OFFSET;
+
+#ifdef DEBUG
+		    old =
+#else
+			(void)
 #endif
+			erts_smp_atomic32_read_band_mb(&proc->state,
+						       ~clr_bits);
+			ASSERT((old & clr_bits) == clr_bits);
+
+		}
+
+		goto handle_next_proc;
 	    }
+
 #ifdef ERTS_DIRTY_SCHEDULERS
-	    else if (state & ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q) {
+
+	    if (ERTS_RUNQ_IX_IS_DIRTY(rq->ix)) {
+		erts_aint32_t dqbit = qbit;
 #ifdef DEBUG
-		erts_aint32_t old =
-#else
-		(void)
+		erts_aint32_t old_dqbit;
 #endif
-		    erts_smp_atomic32_read_band_nob(&proc->state,
-						    ~(ERTS_PSFLG_DIRTY_CPU_PROC
-						      | ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q));
-		/* assert that no other dirty flags are set */
-		ASSERT(!(old & (ERTS_PSFLG_DIRTY_IO_PROC|ERTS_PSFLG_DIRTY_IO_PROC_IN_Q)));
-	    } else if (state & ERTS_PSFLG_DIRTY_IO_PROC_IN_Q) {
+
+		if (rq == ERTS_DIRTY_CPU_RUNQ)
+		    dqbit <<= ERTS_PDSFLGS_IN_CPU_PRQ_MASK_OFFSET;
+		else {
+		    ASSERT(rq == ERTS_DIRTY_IO_RUNQ);
+		    dqbit <<= ERTS_PDSFLGS_IN_IO_PRQ_MASK_OFFSET;
+		}
+
 #ifdef DEBUG
-		erts_aint32_t old =
+		old_dqbit = (int)
 #else
-		(void)
+		    (void)
 #endif
-		    erts_smp_atomic32_read_band_nob(&proc->state,
-						    ~(ERTS_PSFLG_DIRTY_IO_PROC
-						      | ERTS_PSFLG_DIRTY_IO_PROC_IN_Q));
-		/* assert that no other dirty flags are set */
-		ASSERT(!(old & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q)));
+		    erts_smp_atomic32_read_band_mb(&real_proc->dirty_state,
+						   ~dqbit);
+		ASSERT(old_dqbit & dqbit);
 	    }
-	    if (requeue) {
-#else
-	    else {
 #endif
+
+	    if (ERTS_PSFLG_BOUND & real_state) {
+		/* Bound processes get stuck here... */
+		proc->next = NULL;
+		if (sbpp->last)
+		    sbpp->last->next = proc;
+		else
+		    sbpp->first = proc;
+		sbpp->last = proc;
+	    }
+	    else {
 		int prio = (int) ERTS_PSFLGS_GET_PRQ_PRIO(state);
 		erts_smp_runq_unlock(rq);
 
@@ -4031,6 +4020,8 @@ evacuate_run_queue(ErtsRunQueue *rq,
 
 		erts_smp_runq_lock(rq);
 	    }
+
+	handle_next_proc:
 	    proc = dequeue_process(rq, prio_q, &state);
 	}
 	if (notify)
@@ -4965,7 +4956,7 @@ erts_fprintf(stderr, "--------------------------------\n");
 	rq->out_of_work_count = 0;
 	(void) ERTS_RUNQ_FLGS_READ_BSET(rq, ERTS_RUNQ_FLGS_MIGRATION_INFO, flags);
 
-	rq->max_len = rq->len;
+	rq->max_len = erts_smp_atomic32_read_dirty(&rq->len);
 	for (pix = 0; pix < ERTS_NO_PRIO_LEVELS; pix++) {
 	    ErtsRunQueueInfo *rqi;
 	    rqi = (pix == ERTS_PORT_PRIO_LEVEL
@@ -5123,7 +5114,7 @@ wakeup_other_check(ErtsRunQueue *rq, Uint32 flags)
 {
     int wo_reds = rq->wakeup_other_reds;
     if (wo_reds) {
-	int left_len = rq->len - 1;
+	int left_len = erts_smp_atomic32_read_dirty(&rq->len) - 1;
 	if (left_len < 1) {
 	    int wo_reduce = wo_reds << wakeup_other.dec_shift;
 	    wo_reduce &= wakeup_other.dec_mask;
@@ -5196,7 +5187,7 @@ wakeup_other_check_legacy(ErtsRunQueue *rq, Uint32 flags)
 {
     int wo_reds = rq->wakeup_other_reds;
     if (wo_reds) {
-	erts_aint32_t len = rq->len;
+	erts_aint32_t len = erts_smp_atomic32_read_dirty(&rq->len);
 	if (len < 2) {
 	    rq->wakeup_other -= ERTS_WAKEUP_OTHER_DEC_LEGACY*wo_reds;
 	    if (rq->wakeup_other < 0)
@@ -5292,7 +5283,7 @@ runq_supervisor(void *unused)
 	    ErtsRunQueue *rq = ERTS_RUNQ_IX(ix);
 	    if (ERTS_RUNQ_FLGS_GET(rq) & ERTS_RUNQ_FLG_NONEMPTY) {
 		erts_smp_runq_lock(rq);
-		if (rq->len != 0)
+		if (erts_smp_atomic32_read_dirty(&rq->len) != 0)
 		    wake_scheduler_on_empty_runq(rq); /* forced wakeup... */
 		erts_smp_runq_unlock(rq);
 	    }
@@ -5311,17 +5302,11 @@ erts_early_init_scheduling(int no_schedulers)
     wakeup_other.threshold = ERTS_SCHED_WAKEUP_OTHER_THRESHOLD_MEDIUM;
     wakeup_other.type = ERTS_SCHED_WAKEUP_OTHER_TYPE_DEFAULT;
 #endif
-#ifndef ERTS_SCHED_MIN_SPIN
     sched_busy_wait.sys_schedule = ERTS_SCHED_SYS_SLEEP_SPINCOUNT_MEDIUM;
     sched_busy_wait.tse = (ERTS_SCHED_SYS_SLEEP_SPINCOUNT_MEDIUM
 			   * ERTS_SCHED_TSE_SLEEP_SPINCOUNT_FACT);
     sched_busy_wait.aux_work = (ERTS_SCHED_SYS_SLEEP_SPINCOUNT_MEDIUM
 				* ERTS_SCHED_AUX_WORK_SLEEP_SPINCOUNT_FACT_MEDIUM);
-#else
-    sched_busy_wait.sys_schedule = ERTS_SCHED_SYS_SLEEP_SPINCOUNT_NONE;
-    sched_busy_wait.tse = ERTS_SCHED_SYS_SLEEP_SPINCOUNT_NONE;
-    sched_busy_wait.aux_work = ERTS_SCHED_SYS_SLEEP_SPINCOUNT_NONE;
-#endif
 }
 
 int
@@ -5505,9 +5490,6 @@ init_scheduler_data(ErtsSchedulerData* esdp, int num,
     esdp->f_reg_array =
 	erts_alloc_permanent_cache_aligned(ERTS_ALC_T_BEAM_REGISTER,
 					   MAX_REG * sizeof(FloatDef));
-#if !HEAP_ON_C_STACK
-    esdp->num_tmp_heap_used = 0;
-#endif
 #ifdef ERTS_DIRTY_SCHEDULERS
     if (ERTS_RUNQ_IX_IS_DIRTY(runq->ix)) {
 	esdp->no = 0;
@@ -5642,7 +5624,7 @@ erts_init_scheduling(int no_schedulers, int no_schedulers_online
 	}
 	rq->out_of_work_count = 0;
 	rq->max_len = 0;
-	rq->len = 0;
+	erts_smp_atomic32_set_nob(&rq->len, 0);
 	rq->wakeup_other = 0;
 	rq->wakeup_other_reds = 0;
 	rq->halt_in_progress = 0;
@@ -5792,9 +5774,7 @@ erts_init_scheduling(int no_schedulers, int no_schedulers_online
 #endif
 
     init_misc_aux_work();
-#if !HALFWORD_HEAP
     init_swtreq_alloc();
-#endif
 
     erts_atomic32_init_nob(&debug_wait_completed_count, 0); /* debug only */
     debug_wait_completed_flags = 0;
@@ -5974,19 +5954,96 @@ make_proxy_proc(Process *prev_proxy, Process *proc, erts_aint32_t prio)
     return proxy;
 }
 
-static ERTS_INLINE void
-free_proxy_proc(Process *proxy)
-{
-    ASSERT(erts_smp_atomic32_read_nob(&proxy->state) & ERTS_PSFLG_PROXY);
-    erts_free(ERTS_ALC_T_PROC, proxy);
-}
-
 #define ERTS_ENQUEUE_NOT 0
 #define ERTS_ENQUEUE_NORMAL_QUEUE 1
-#ifdef ERTS_DIRTY_SCHEDULERS
 #define ERTS_ENQUEUE_DIRTY_CPU_QUEUE 2
 #define ERTS_ENQUEUE_DIRTY_IO_QUEUE 3
+
+#ifdef ERTS_DIRTY_SCHEDULERS
+
+static int
+check_dirty_enqueue_in_prio_queue(Process *c_p,
+				  erts_aint32_t *newp,
+				  erts_aint32_t actual,
+				  erts_aint32_t aprio,
+				  erts_aint32_t qbit)
+{
+    int queue;
+    erts_aint32_t dact, max_qbit;
+
+    /* Termination should be done on an ordinary scheduler */
+    if (actual & ERTS_PSFLG_EXITING) {
+	*newp &= ~ERTS_PSFLGS_DIRTY_WORK;
+	return ERTS_ENQUEUE_NORMAL_QUEUE;
+    }
+
+    /*
+     * If we have system tasks, we enqueue on ordinary run-queue
+     * and take care of those system tasks first.
+     */
+    if (actual & ERTS_PSFLG_ACTIVE_SYS)
+	return ERTS_ENQUEUE_NORMAL_QUEUE;
+
+    dact = erts_smp_atomic32_read_mb(&c_p->dirty_state);
+    if (actual & (ERTS_PSFLG_DIRTY_ACTIVE_SYS
+		  | ERTS_PSFLG_DIRTY_CPU_PROC)) {
+	max_qbit = ((dact >> ERTS_PDSFLGS_IN_CPU_PRQ_MASK_OFFSET)
+		    & ERTS_PDSFLGS_QMASK);
+	queue = ERTS_ENQUEUE_DIRTY_CPU_QUEUE;
+    }
+    else {
+	ASSERT(actual & ERTS_PSFLG_DIRTY_IO_PROC);
+	max_qbit = ((dact >> ERTS_PDSFLGS_IN_IO_PRQ_MASK_OFFSET)
+		    & ERTS_PDSFLGS_QMASK);
+	queue = ERTS_ENQUEUE_DIRTY_IO_QUEUE;
+    }
+
+    max_qbit |= 1 << ERTS_PSFLGS_QMASK_BITS;
+    max_qbit &= -max_qbit;
+
+    if (qbit >= max_qbit)
+	return ERTS_ENQUEUE_NOT; /* Already queued in higher or equal prio */
+    if ((actual & (ERTS_PSFLG_IN_RUNQ|ERTS_PSFLGS_USR_PRIO_MASK))
+	!= (aprio << ERTS_PSFLGS_USR_PRIO_OFFSET)) {
+	/*
+	 * Process struct already enqueued, or actual prio not
+	 * equal to user prio, i.e., enqueue using proxy.
+	 */
+	return -1*queue;
+    }
+
+    *newp |= ERTS_PSFLG_IN_RUNQ;
+    return queue;
+}
+
+static ERTS_INLINE int
+fin_dirty_enq_s_change(Process *p,
+		       int pstruct_reserved,
+		       erts_aint32_t enq_prio,
+		       int qmask_offset)
+{
+    erts_aint32_t qbit = 1 << enq_prio;
+    qbit <<= qmask_offset;
+
+    if (qbit & erts_smp_atomic32_read_bor_mb(&p->dirty_state, qbit)) {
+	/* Already enqueue by someone else... */
+	if (pstruct_reserved) {
+	    /* We reserved process struct for enqueue; clear it... */
+#ifdef DEBUG
+	    erts_aint32_t old =
+#else
+		(void)
 #endif
+		erts_smp_atomic32_read_band_nob(&p->state, ~ERTS_PSFLG_IN_RUNQ);
+	    ASSERT(old & ERTS_PSFLG_IN_RUNQ);
+	}
+	return 0;
+    }
+
+    return !0;
+}
+
+#endif /* ERTS_DIRTY_SCHEDULERS */
 
 static ERTS_INLINE int
 check_enqueue_in_prio_queue(Process *c_p,
@@ -6002,61 +6059,14 @@ check_enqueue_in_prio_queue(Process *c_p,
     *prq_prio_p = aprio;
 
 #ifdef ERTS_DIRTY_SCHEDULERS
-    if (actual & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC)) {
-        /*
-         * If we have system tasks of a priority higher
-         * or equal to the user priority, we enqueue
-         * on ordinary run-queue and take care of
-         * those system tasks first.
-         */
-        if (actual & ERTS_PSFLG_ACTIVE_SYS) {
-            erts_aint32_t uprio, stprio, qmask;
-            uprio = (actual >> ERTS_PSFLGS_USR_PRIO_OFFSET) & ERTS_PSFLGS_PRIO_MASK;
-            if (aprio < uprio)
-                goto enqueue_normal_runq; /* system tasks with higher prio */
-            erts_smp_proc_lock(c_p, ERTS_PROC_LOCK_STATUS);
-            qmask = c_p->sys_task_qs->qmask;
-            erts_smp_proc_unlock(c_p, ERTS_PROC_LOCK_STATUS);
-            switch (qmask & -qmask) {
-            case MAX_BIT:
-                stprio = PRIORITY_MAX;
-                break;
-            case HIGH_BIT:
-                stprio = PRIORITY_HIGH;
-                break;
-            case NORMAL_BIT:
-                stprio = PRIORITY_NORMAL;
-                break;
-            case LOW_BIT:
-                stprio = PRIORITY_LOW;
-                break;
-            default:
-                stprio = PRIORITY_LOW+1;
-                break;
-            }
-            if (stprio <= uprio)
-                goto enqueue_normal_runq; /* system tasks with higher prio */
-        }
-
-        /* Enqueue in dirty run queue if not already enqueued */
-	if (actual & (ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q|ERTS_PSFLG_DIRTY_IO_PROC_IN_Q))
-	    return ERTS_ENQUEUE_NOT; /* already in queue */
-        if (actual & ERTS_PSFLG_DIRTY_CPU_PROC) {
-	    *newp |= ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q;
-            if (actual & ERTS_PSFLG_IN_RUNQ)
-                return -ERTS_ENQUEUE_DIRTY_CPU_QUEUE; /* use proxy */
-	    *newp |= ERTS_PSFLG_IN_RUNQ;
-            return ERTS_ENQUEUE_DIRTY_CPU_QUEUE;
-        }
-	*newp |= ERTS_PSFLG_DIRTY_IO_PROC_IN_Q;
-        if (actual & ERTS_PSFLG_IN_RUNQ)
-            return -ERTS_ENQUEUE_DIRTY_IO_QUEUE; /* use proxy */
-	*newp |= ERTS_PSFLG_IN_RUNQ;
-        return ERTS_ENQUEUE_DIRTY_IO_QUEUE;
+    if (actual & ERTS_PSFLGS_DIRTY_WORK) {
+	int res = check_dirty_enqueue_in_prio_queue(c_p, newp, actual,
+						    aprio, qbit);
+	if (res != ERTS_ENQUEUE_NORMAL_QUEUE)
+	    return res;
     }
-
- enqueue_normal_runq:
 #endif
+
     max_qbit = (actual >> ERTS_PSFLGS_IN_PRQ_MASK_OFFSET) & ERTS_PSFLGS_QMASK;
     max_qbit |= 1 << ERTS_PSFLGS_QMASK_BITS;
     max_qbit &= -max_qbit;
@@ -6088,6 +6098,65 @@ check_enqueue_in_prio_queue(Process *c_p,
     return ERTS_ENQUEUE_NORMAL_QUEUE;
 }
 
+static ERTS_INLINE ErtsRunQueue *
+select_enqueue_run_queue(int enqueue, int enq_prio, Process *p, erts_aint32_t state)
+{
+
+    switch (enqueue) {
+
+    case ERTS_ENQUEUE_NOT:
+
+	return NULL;
+
+#ifdef ERTS_DIRTY_SCHEDULERS
+
+    case ERTS_ENQUEUE_DIRTY_CPU_QUEUE:
+    case -ERTS_ENQUEUE_DIRTY_CPU_QUEUE:
+
+	if (fin_dirty_enq_s_change(p, enqueue > 0, enq_prio,
+				   ERTS_PDSFLGS_IN_CPU_PRQ_MASK_OFFSET))
+	    return ERTS_DIRTY_CPU_RUNQ;
+
+	return NULL;
+
+
+    case ERTS_ENQUEUE_DIRTY_IO_QUEUE:
+    case -ERTS_ENQUEUE_DIRTY_IO_QUEUE:
+
+	if (fin_dirty_enq_s_change(p, enqueue > 0, enq_prio,
+				   ERTS_PDSFLGS_IN_IO_PRQ_MASK_OFFSET))
+	    return ERTS_DIRTY_IO_RUNQ;
+
+	return NULL;
+
+#endif
+
+    default: {
+	ErtsRunQueue* runq;
+
+	ASSERT(enqueue == ERTS_ENQUEUE_NORMAL_QUEUE
+	       || enqueue == -ERTS_ENQUEUE_NORMAL_QUEUE);
+
+	runq = erts_get_runq_proc(p);
+
+#ifdef ERTS_SMP
+	if (!(ERTS_PSFLG_BOUND & state)) {
+	    ErtsRunQueue *new_runq = erts_check_emigration_need(runq, enq_prio);
+	    if (new_runq) {
+		RUNQ_SET_RQ(&p->run_queue, new_runq);
+		runq = new_runq;
+	    }
+	}
+#endif
+
+	ASSERT(runq);
+
+	return runq;
+    }
+    }
+}
+
+
 /*
  * schedule_out_process() return with c_rq locked.
  */
@@ -6096,11 +6165,7 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p, Proces
 {
     erts_aint32_t a, e, n, enq_prio = -1;
     int enqueue; /* < 0 -> use proxy */
-    Process* sched_p;
     ErtsRunQueue* runq;
-#ifdef ERTS_SMP
-    int check_emigration_need;
-#endif
 
     a = state;
 
@@ -6112,7 +6177,7 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p, Proces
 	enqueue = ERTS_ENQUEUE_NOT;
 
 	n &= ~(ERTS_PSFLG_RUNNING|ERTS_PSFLG_RUNNING_SYS);
-	if (a & ERTS_PSFLG_ACTIVE_SYS
+	if (a & (ERTS_PSFLG_ACTIVE_SYS|ERTS_PSFLG_DIRTY_ACTIVE_SYS)
 	    || (a & (ERTS_PSFLG_ACTIVE|ERTS_PSFLG_SUSPENDED)) == ERTS_PSFLG_ACTIVE) {
 	    enqueue = check_enqueue_in_prio_queue(p, &enq_prio, &n, a);
 	}
@@ -6121,16 +6186,17 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p, Proces
 	    break;
     }
 
-    switch (enqueue) {
-    case ERTS_ENQUEUE_NOT:
+    runq = select_enqueue_run_queue(enqueue, enq_prio, p, n);
+
+    if (!runq) {
+
 	if (erts_system_profile_flags.runnable_procs) {
 
 	    /* Status lock prevents out of order "runnable proc" trace msgs */
 	    ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_STATUS & erts_proc_lc_my_proc_locks(p));
 
-	    if (!(a & ERTS_PSFLG_ACTIVE_SYS)
-		&& (!(a & ERTS_PSFLG_ACTIVE)
-		    || (a & ERTS_PSFLG_SUSPENDED))) {
+	    if (!(a & (ERTS_PSFLG_ACTIVE_SYS|ERTS_PSFLG_DIRTY_ACTIVE_SYS))
+		&& (!(a & ERTS_PSFLG_ACTIVE) || (a & ERTS_PSFLG_SUSPENDED))) {
 		/* Process inactive */
 		profile_runnable_proc(p, am_inactive);
 	    }
@@ -6143,98 +6209,76 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p, Proces
 
 	return 0;
 
-#ifdef ERTS_DIRTY_SCHEDULERS
-#ifdef ERTS_SMP
-    case ERTS_ENQUEUE_DIRTY_CPU_QUEUE:
-    case -ERTS_ENQUEUE_DIRTY_CPU_QUEUE:
-	runq = ERTS_DIRTY_CPU_RUNQ;
-	ASSERT(ERTS_SCHEDULER_IS_DIRTY_CPU(runq->scheduler));
-#ifdef ERTS_SMP
-	check_emigration_need = 0;
-#endif
-	break;
+    }
+    else {
+	Process* sched_p;
 
-    case ERTS_ENQUEUE_DIRTY_IO_QUEUE:
-    case -ERTS_ENQUEUE_DIRTY_IO_QUEUE:
-	runq = ERTS_DIRTY_IO_RUNQ;
-	ASSERT(ERTS_SCHEDULER_IS_DIRTY_IO(runq->scheduler));
-#ifdef ERTS_SMP
-	check_emigration_need = 0;
-#endif
-	break;
-#endif
-#endif
+	ASSERT(!(n & ERTS_PSFLG_SUSPENDED) || (n & (ERTS_PSFLG_ACTIVE_SYS
+						    | ERTS_PSFLG_DIRTY_ACTIVE_SYS)));
 
-    default:
-	ASSERT(enqueue == ERTS_ENQUEUE_NORMAL_QUEUE
-	       || enqueue == -ERTS_ENQUEUE_NORMAL_QUEUE);
+	if (enqueue < 0)
+	    sched_p = make_proxy_proc(proxy, p, enq_prio);
+	else {
+	    sched_p = p;
+	    if (proxy)
+		free_proxy_proc(proxy);
+	}
 
-	runq = erts_get_runq_proc(p);
-#ifdef ERTS_SMP
-	check_emigration_need = !(ERTS_PSFLG_BOUND & n);
-#endif
-	break;
-    }
+	ASSERT(runq);
 
-    ASSERT(!(n & ERTS_PSFLG_SUSPENDED) || (n & ERTS_PSFLG_ACTIVE_SYS));
+	erts_smp_runq_lock(runq);
 
-    if (enqueue < 0)
-	sched_p = make_proxy_proc(proxy, p, enq_prio);
-    else {
-	sched_p = p;
-	if (proxy)
-	    free_proxy_proc(proxy);
-    }
+	/* Enqueue the process */
+	enqueue_process(runq, (int) enq_prio, sched_p);
 
-#ifdef ERTS_SMP
-    if (check_emigration_need) {
-	ErtsRunQueue *new_runq = erts_check_emigration_need(runq, enq_prio);
-	if (new_runq) {
-	    RUNQ_SET_RQ(&sched_p->run_queue, new_runq);
-	    runq = new_runq;
-	}
-    }
-#endif
+	if (runq == c_rq)
+	    return 1;
 
-    ASSERT(runq);
+	erts_smp_runq_unlock(runq);
 
-    erts_smp_runq_lock(runq);
+	smp_notify_inc_runq(runq);
 
-    /* Enqueue the process */
-    enqueue_process(runq, (int) enq_prio, sched_p);
+	erts_smp_runq_lock(c_rq);
 
-    if (runq == c_rq)
 	return 1;
-    erts_smp_runq_unlock(runq);
-    smp_notify_inc_runq(runq);
-    erts_smp_runq_lock(c_rq);
-    return 1;
+    }
+
 }
 
 static ERTS_INLINE void
-add2runq(Process *p, erts_aint32_t state, erts_aint32_t prio)
+add2runq(int enqueue, erts_aint32_t prio,
+	 Process *proc, erts_aint32_t state,
+	 Process **proxy)
 {
-    ErtsRunQueue *runq = erts_get_runq_proc(p);
+    ErtsRunQueue *runq;
 
-#ifdef ERTS_SMP
-    if (!(ERTS_PSFLG_BOUND & state)) {
-	ErtsRunQueue *new_runq = erts_check_emigration_need(runq, (int) prio);
-	if (new_runq) {
-	    RUNQ_SET_RQ(&p->run_queue, new_runq);
-	    runq = new_runq;
-	}
-    }
-#endif
-    ASSERT(runq);
+    runq = select_enqueue_run_queue(enqueue, prio, proc, state);
+
+    if (runq) {
+	Process *sched_p;
 
-    erts_smp_runq_lock(runq);
+	if (enqueue > 0)
+	    sched_p = proc;
+	else {
+	    Process *pxy;
+
+	    if (!proxy)
+		pxy = NULL;
+	    else {
+		pxy = *proxy;
+		*proxy = NULL;
+	    }
+	    sched_p = make_proxy_proc(pxy, proc, prio);
+	}
 
-    /* Enqueue the process */
-    enqueue_process(runq, (int) prio, p);
+	erts_smp_runq_lock(runq);
 
-    erts_smp_runq_unlock(runq);
-    smp_notify_inc_runq(runq);
+	/* Enqueue the process */
+	enqueue_process(runq, (int) prio, sched_p);
 
+	erts_smp_runq_unlock(runq);
+	smp_notify_inc_runq(runq);
+    }
 }
 
 static ERTS_INLINE int
@@ -6340,10 +6384,7 @@ schedule_process(Process *p, erts_aint32_t in_state, ErtsProcLocks locks)
 					     &state,
 					     &enq_prio,
 					     locks);
-    if (enqueue != ERTS_ENQUEUE_NOT)
-	add2runq(enqueue > 0 ? p : make_proxy_proc(NULL, p, enq_prio),
-		 state,
-		 enq_prio);
+    add2runq(enqueue, enq_prio, p, state, NULL);
 }
 
 void
@@ -6352,22 +6393,99 @@ erts_schedule_process(Process *p, erts_aint32_t state, ErtsProcLocks locks)
     schedule_process(p, state, locks);
 }
 
-static void
-schedule_process_sys_task(Process *p, erts_aint32_t state, Process *proxy)
+static int
+schedule_process_sys_task(Process *p, erts_aint32_t prio, ErtsProcSysTask *st)
 {
-    /*
-     * Expects status lock to be locked when called, and
-     * returns with status lock unlocked...
-     */
-    erts_aint32_t a = state, n, enq_prio = -1;
+    int res;
+    int locked;
+    ErtsProcSysTaskQs *stqs, *free_stqs;
+    erts_aint32_t state, a, n, enq_prio;
     int enqueue; /* < 0 -> use proxy */
-    unsigned int prof_runnable_procs = erts_system_profile_flags.runnable_procs;
+    unsigned int prof_runnable_procs;
+
+    res = 1; /* prepare for success */
+    st->next = st->prev = st; /* Prep for empty prio queue */
+    state = erts_smp_atomic32_read_nob(&p->state);
+    prof_runnable_procs = erts_system_profile_flags.runnable_procs;
+    locked = 0;
+    free_stqs = NULL;
+    if (state & ERTS_PSFLG_ACTIVE_SYS)
+	stqs = NULL;
+    else {
+    alloc_qs:
+	stqs = proc_sys_task_queues_alloc();
+	stqs->qmask = 1 << prio;
+	stqs->ncount = 0;
+	stqs->q[PRIORITY_MAX] = NULL;
+	stqs->q[PRIORITY_HIGH] = NULL;
+	stqs->q[PRIORITY_NORMAL] = NULL;
+	stqs->q[PRIORITY_LOW] = NULL;
+	stqs->q[prio] = st;
+    }
+
+    if (!locked) {
+	locked = 1;
+	erts_smp_proc_lock(p, ERTS_PROC_LOCK_STATUS);
+
+	state = erts_smp_atomic32_read_nob(&p->state);
+	if (state & ERTS_PSFLG_EXITING) {
+	    free_stqs = stqs;
+	    res = 0;
+	    goto cleanup;
+	}
+    }
+
+    if (!p->sys_task_qs) {
+	if (stqs)
+	    p->sys_task_qs = stqs;
+	else
+	    goto alloc_qs;
+    }
+    else {
+	free_stqs = stqs;
+	stqs = p->sys_task_qs;
+	if (!stqs->q[prio]) {
+	    stqs->q[prio] = st;
+	    stqs->qmask |= 1 << prio;
+	}
+	else {
+	    st->next = stqs->q[prio];
+	    st->prev = stqs->q[prio]->prev;
+	    st->next->prev = st;
+	    st->prev->next = st;
+	    ASSERT(stqs->qmask & (1 << prio));
+	}
+    }
+
+    if (ERTS_PSFLGS_GET_ACT_PRIO(state) > prio) {
+	erts_aint32_t n, a, e;
+	/* Need to elevate actual prio */
+
+	a = state;
+	do {
+	    if (ERTS_PSFLGS_GET_ACT_PRIO(a) <= prio) {
+		n = a;
+		break;
+	    }
+	    n = e = a;
+	    n &= ~ERTS_PSFLGS_ACT_PRIO_MASK;
+	    n |= (prio << ERTS_PSFLGS_ACT_PRIO_OFFSET);
+	    a = erts_smp_atomic32_cmpxchg_nob(&p->state, n, e);    
+	} while (a != e);
+	state = n;
+    }
+
+
+    a = state;
+    enq_prio = -1;
 
     /* Status lock prevents out of order "runnable proc" trace msgs */
     ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_STATUS & erts_proc_lc_my_proc_locks(p));
 
-    if (!prof_runnable_procs)
+    if (!prof_runnable_procs) {
 	erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
+	locked = 0;
+    }
 
     ASSERT(!(state & ERTS_PSFLG_PROXY));
 
@@ -6375,8 +6493,10 @@ schedule_process_sys_task(Process *p, erts_aint32_t state, Process *proxy)
 	erts_aint32_t e;
 	n = e = a;
 
-	if (a & ERTS_PSFLG_FREE)
+	if (a & ERTS_PSFLG_FREE) {
+	    res = 0;
 	    goto cleanup; /* We don't want to schedule free processes... */
+	}
 
 	enqueue = ERTS_ENQUEUE_NOT;
 	n |= ERTS_PSFLG_ACTIVE_SYS;
@@ -6400,29 +6520,22 @@ schedule_process_sys_task(Process *p, erts_aint32_t state, Process *proxy)
 	}
 
 	erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
-	prof_runnable_procs = 0;
+	locked = 0;
     }
 
-    if (enqueue != ERTS_ENQUEUE_NOT) {
-	Process *sched_p;
-	if (enqueue > 0)
-	    sched_p = p;
-	else {
-	    sched_p = make_proxy_proc(proxy, p, enq_prio);
-	    proxy = NULL;
-	}
-	add2runq(sched_p, n, enq_prio);
-    }
+    add2runq(enqueue, enq_prio, p, n, NULL);
 
 cleanup:
 
-    if (prof_runnable_procs)
+    if (locked)
 	erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
 
-    if (proxy)
-	free_proxy_proc(proxy);
+    if (free_stqs)
+	proc_sys_task_queues_free(free_stqs);
 
     ERTS_SMP_LC_ASSERT(!(ERTS_PROC_LOCK_STATUS & erts_proc_lc_my_proc_locks(p)));
+
+    return res;
 }
 
 static ERTS_INLINE int
@@ -6464,9 +6577,6 @@ suspend_process(Process *c_p, Process *p)
 
     if (suspended) {
 
-	ASSERT(!(ERTS_PSFLG_RUNNING & state)
-	       || p == erts_get_current_process());
-
 	if (suspended > 0 && erts_system_profile_flags.runnable_procs) {
 
 	    /* 'state' is before our change... */
@@ -6508,10 +6618,7 @@ resume_process(Process *p, ErtsProcLocks locks)
 					 &state,
 					 &enq_prio,
 					 locks);
-    if (enqueue)
-	add2runq(enqueue > 0 ? p : make_proxy_proc(NULL, p, enq_prio),
-		 state,
-		 enq_prio);
+    add2runq(enqueue, enq_prio, p, state, NULL);
 }
 
 int
@@ -6798,18 +6905,19 @@ suspend_scheduler(ErtsSchedulerData *esdp)
 			 & ERTS_RUNQ_FLGS_QMASK);
 		aux_work = erts_atomic32_read_acqb(&ssi->aux_work);
 		if (aux_work|qmask) {
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp) && !thr_prgr_active) {
-			erts_thr_progress_active(esdp, thr_prgr_active = 1);
-			sched_wall_time_change(esdp, 1);
+		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+			if (!thr_prgr_active) {
+			    erts_thr_progress_active(esdp, thr_prgr_active = 1);
+			    sched_wall_time_change(esdp, 1);
+			}
+			if (aux_work)
+			    aux_work = handle_aux_work(&esdp->aux_work_data,
+						       aux_work,
+						       1);
+
+			if (aux_work && erts_thr_progress_update(esdp))
+			    erts_thr_progress_leader_update(esdp);
 		    }
-		    if (aux_work)
-			aux_work = handle_aux_work(&esdp->aux_work_data,
-						   aux_work,
-						   1);
-
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp) &&
-			(aux_work && erts_thr_progress_update(esdp)))
-			erts_thr_progress_leader_update(esdp);
 		    if (qmask) {
 #ifdef ERTS_DIRTY_SCHEDULERS
 			if (ERTS_SCHEDULER_IS_DIRTY(esdp)) {
@@ -7026,17 +7134,18 @@ suspend_scheduler(ErtsSchedulerData *esdp)
 			 & ERTS_RUNQ_FLGS_QMASK);
 		aux_work = erts_atomic32_read_acqb(&ssi->aux_work);
 		if (aux_work|qmask) {
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp) && !thr_prgr_active) {
-			erts_thr_progress_active(esdp, thr_prgr_active = 1);
-			sched_wall_time_change(esdp, 1);
+		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+			if (!thr_prgr_active) {
+			    erts_thr_progress_active(esdp, thr_prgr_active = 1);
+			    sched_wall_time_change(esdp, 1);
+			}
+			if (aux_work)
+			    aux_work = handle_aux_work(&esdp->aux_work_data,
+						       aux_work,
+						       1);
+			if (aux_work && erts_thr_progress_update(esdp))
+			    erts_thr_progress_leader_update(esdp);
 		    }
-		    if (aux_work)
-			aux_work = handle_aux_work(&esdp->aux_work_data,
-						   aux_work,
-						   1);
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp) && aux_work &&
-			erts_thr_progress_update(esdp))
-			erts_thr_progress_leader_update(esdp);
 		    if (qmask) {
 			erts_smp_runq_lock(esdp->run_queue);
 			evacuate_run_queue(esdp->run_queue, &sbp);
@@ -7939,6 +8048,9 @@ sched_thread_func(void *vesdp)
 
     erts_sched_init_time_sup(esdp);
 
+    (void) ERTS_RUNQ_FLGS_SET_NOB(esdp->run_queue,
+				  ERTS_RUNQ_FLG_EXEC);
+
 #ifdef ERTS_SMP
     tse = erts_tse_fetch();
     erts_tse_prepare_timed(tse);
@@ -7949,6 +8061,8 @@ sched_thread_func(void *vesdp)
     callbacks.wait = thr_prgr_wait;
     callbacks.finalize_wait = thr_prgr_fin_wait;
 
+    erts_msacc_init_thread("scheduler", no, 1);
+
     erts_thr_progress_register_managed_thread(esdp, &callbacks, 0);
     erts_alloc_register_scheduler(vesdp);
 #endif
@@ -8204,18 +8318,12 @@ erts_start_schedulers(void)
 
 	erts_snprintf(opts.name, 16, "%lu_scheduler", actual + 1);
 
-#ifdef __OSE__
-        /* This should be done in the bind strategy */
-	opts.coreNo = (actual+1) % ose_num_cpus();
-#endif
-
 	res = ethr_thr_create(&esdp->tid, sched_thread_func, (void*)esdp, &opts);
 
 	if (res != 0) {
            break;
 	}
     }
-
     erts_no_schedulers = actual;
 
 #ifdef ERTS_DIRTY_SCHEDULERS
@@ -8244,10 +8352,6 @@ erts_start_schedulers(void)
 
     erts_snprintf(opts.name, 16, "aux");
 
-#ifdef __OSE__
-    opts.coreNo = 0;
-#endif /* __OSE__ */
-
     res = ethr_thr_create(&aux_tid, aux_thread, NULL, &opts);
     if (res != 0)
 	erts_exit(ERTS_ERROR_EXIT, "Failed to create aux thread\n");
@@ -8267,7 +8371,6 @@ erts_start_schedulers(void)
 		      actual, actual == 1 ? " was" : "s were");
 	erts_send_error_to_logger_nogl(dsbufp);
     }
-
 }
 
 #endif /* ERTS_SMP */
@@ -8286,7 +8389,7 @@ add_pend_suspend(Process *suspendee,
 					 sizeof(ErtsPendingSuspend));
     psp->next = NULL;
 #ifdef DEBUG
-#if defined(ARCH_64) && !HALFWORD_HEAP
+#if defined(ARCH_64)
     psp->end = (ErtsPendingSuspend *) 0xdeaddeaddeaddead;
 #else
     psp->end = (ErtsPendingSuspend *) 0xdeaddead;
@@ -8408,9 +8511,8 @@ pid2proc_not_running(Process *c_p, ErtsProcLocks c_p_locks,
 	    resume_process(rp, rp_locks);
     }
     else {
-
 	rp = erts_pid2proc(c_p, c_p_locks|ERTS_PROC_LOCK_STATUS,
-			   pid, pid_locks|ERTS_PROC_LOCK_STATUS);
+			   pid, ERTS_PROC_LOCK_STATUS);
 
 	if (!rp) {
 	    c_p->flags &= ~F_P2PNR_RESCHED;
@@ -8419,40 +8521,84 @@ pid2proc_not_running(Process *c_p, ErtsProcLocks c_p_locks,
 
 	ASSERT(!(c_p->flags & F_P2PNR_RESCHED));
 
-	if (suspend) {
-	    if (suspend_process(c_p, rp))
-		goto done;
-	}
-	else {
-	    if (!((ERTS_PSFLG_RUNNING|ERTS_PSFLG_RUNNING_SYS)
-		  & erts_smp_atomic32_read_acqb(&rp->state)))
-		goto done;
+	/*
+	 * Suspend the other process in order to prevent
+	 * it from being selected for normal execution.
+	 * This will however not prevent it from being
+	 * selected for execution of a system task. If
+	 * it is selected for execution of a system task
+	 * we might be blocked for quite a while if the
+	 * try-lock below fails. That is, there is room
+	 * for improvement here...
+	 */
 
-	}
+	if (!suspend_process(c_p, rp)) {
+	    /* Other process running */
 
-	/* Other process running */
+	    ASSERT(ERTS_PSFLG_RUNNING
+		   & erts_smp_atomic32_read_nob(&rp->state));
 
-	/*
-	 * If we got pending suspenders and suspend ourselves waiting
-	 * to suspend another process we might deadlock.
-	 * In this case we have to yield, be suspended by
-	 * someone else and then do it all over again.
-	 */
-	if (!c_p->pending_suspenders) {
-	    /* Mark rp pending for suspend by c_p */
-	    add_pend_suspend(rp, c_p->common.id, handle_pend_sync_suspend);
-	    ASSERT(is_nil(c_p->suspendee));
+	running:
 
-	    /* Suspend c_p; when rp is suspended c_p will be resumed. */
-	    suspend_process(c_p, c_p);
-	    c_p->flags |= F_P2PNR_RESCHED;
+	    /*
+	     * If we got pending suspenders and suspend ourselves waiting
+	     * to suspend another process we might deadlock.
+	     * In this case we have to yield, be suspended by
+	     * someone else and then do it all over again.
+	     */
+	    if (!c_p->pending_suspenders) {
+		/* Mark rp pending for suspend by c_p */
+		add_pend_suspend(rp, c_p->common.id, handle_pend_sync_suspend);
+		ASSERT(is_nil(c_p->suspendee));
+
+		/* Suspend c_p; when rp is suspended c_p will be resumed. */
+		suspend_process(c_p, c_p);
+		c_p->flags |= F_P2PNR_RESCHED;
+	    }
+	    /* Yield (caller is assumed to yield immediately in bif). */
+	    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_STATUS);
+	    rp = ERTS_PROC_LOCK_BUSY;
+	}
+	else {
+	    ErtsProcLocks need_locks = pid_locks & ~ERTS_PROC_LOCK_STATUS;
+	    if (need_locks && erts_smp_proc_trylock(rp, need_locks) == EBUSY) {
+		if (ERTS_PSFLG_RUNNING_SYS
+		    & erts_smp_atomic32_read_nob(&rp->state)) {
+		    /* Executing system task... */
+		    resume_process(rp, ERTS_PROC_LOCK_STATUS);
+		    goto running;
+		}
+		erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_STATUS);
+		/*
+		 * If we are unlucky, the process just got selected for
+		 * execution of a system task. In this case we may be
+		 * blocked here for quite a while... Execution of system
+		 * tasks are fortunately quite rare events. We try to
+		 * avoid this by checking if it is in a state executing
+		 * system tasks (above), but it will not prevent all
+		 * scenarios for a long block here...
+		 */
+		rp = erts_pid2proc(c_p, c_p_locks|ERTS_PROC_LOCK_STATUS,
+				   pid, pid_locks|ERTS_PROC_LOCK_STATUS);
+		if (!rp)
+		    goto done;
+	    }
+
+	    /*
+	     * The previous suspend has prevented the process
+	     * from being selected for normal execution regardless
+	     * of locks held or not held on it...
+	     */
+	    ASSERT(!(ERTS_PSFLG_RUNNING
+		     & erts_smp_atomic32_read_nob(&rp->state)));
+
+	    if (!suspend)
+		resume_process(rp, pid_locks|ERTS_PROC_LOCK_STATUS);
 	}
-	/* Yield (caller is assumed to yield immediately in bif). */
-	erts_smp_proc_unlock(rp, pid_locks|ERTS_PROC_LOCK_STATUS);
-	rp = ERTS_PROC_LOCK_BUSY;
     }
 
  done:
+	
     if (rp && rp != ERTS_PROC_LOCK_BUSY && !(pid_locks & ERTS_PROC_LOCK_STATUS))
 	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_STATUS);
     if (unlock_c_p_status)
@@ -8947,24 +9093,39 @@ resume_process_1(BIF_ALIST_1)
 }
 
 Uint
-erts_run_queues_len(Uint *qlen)
+erts_run_queues_len(Uint *qlen, int atomic_queues_read, int incl_active_sched)
 {
     int i = 0;
     Uint len = 0;
-    ERTS_ATOMIC_FOREACH_RUNQ(rq,
-    {
-	Sint pqlen = 0;
-	int pix;
-	for (pix = 0; pix < ERTS_NO_PROC_PRIO_LEVELS; pix++)
-	    pqlen += RUNQ_READ_LEN(&rq->procs.prio_info[pix].len);
+    if (atomic_queues_read)
+	ERTS_ATOMIC_FOREACH_RUNQ(rq,
+	 {
+	     Sint rq_len = (Sint) erts_smp_atomic32_read_dirty(&rq->len);
+	     ASSERT(rq_len >= 0);
+	     if (incl_active_sched
+		 && (ERTS_RUNQ_FLGS_GET_NOB(rq) & ERTS_RUNQ_FLG_EXEC)) {
+		 rq_len++;
+	     }
+	     if (qlen)
+		 qlen[i++] = rq_len;
+	     len += (Uint) rq_len;
+	 }
+	    );
+    else {
+	for (i = 0; i < erts_no_run_queues; i++) {
+	    ErtsRunQueue *rq = ERTS_RUNQ_IX(i);
+	    Sint rq_len = (Sint) erts_smp_atomic32_read_nob(&rq->len);
+	    ASSERT(rq_len >= 0);
+	     if (incl_active_sched
+		 && (ERTS_RUNQ_FLGS_GET_NOB(rq) & ERTS_RUNQ_FLG_EXEC)) {
+		 rq_len++;
+	     }
+	    if (qlen)
+		qlen[i] = rq_len;
+	    len += (Uint) rq_len;
+	}
 
-	if (pqlen < 0)
-	    pqlen = 0;
- 	if (qlen)
-	    qlen[i++] = pqlen;
-	len += pqlen;
     }
-	);
     return len;
 }
 
@@ -9223,6 +9384,8 @@ Process *schedule(Process *p, int calls)
     Uint32 flags;
     erts_aint32_t state = 0; /* Supress warning... */
 
+    ERTS_MSACC_DECLARE_CACHE();
+
 #ifdef USE_VM_PROBES
     if (p != NULL && DTRACE_ENABLED(process_unscheduled)) {
         DTRACE_CHARBUF(process_buf, DTRACE_TERM_BUF_SIZE);
@@ -9257,6 +9420,8 @@ Process *schedule(Process *p, int calls)
     } else {
     sched_out_proc:
 
+	ASSERT(!(p->flags & F_DELAY_GC));
+
 #ifdef ERTS_SMP
 	ERTS_SMP_CHK_HAVE_ONLY_MAIN_PROC_LOCK(p);
 	esdp = p->scheduler_data;
@@ -9325,6 +9490,8 @@ Process *schedule(Process *p, int calls)
 
 	erts_smp_proc_unlock(p, ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_STATUS);
 
+        ERTS_MSACC_SET_STATE_CACHED_M(ERTS_MSACC_STATE_OTHER);
+
 	if (state & ERTS_PSFLG_FREE) {
 #ifdef ERTS_SMP
 	    ASSERT(esdp->free_process == p);
@@ -9361,15 +9528,16 @@ Process *schedule(Process *p, int calls)
 #ifdef ERTS_SMP
 	ErtsMigrationPaths *mps;
 	ErtsMigrationPath *mp;
-	ErtsProcList *pnd_xtrs = rq->procs.pending_exiters;
-	if (erts_proclist_fetch(&pnd_xtrs, NULL)) {
+
+	if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+	    ErtsProcList *pnd_xtrs = rq->procs.pending_exiters;
+	    if (erts_proclist_fetch(&pnd_xtrs, NULL)) {
 	    rq->procs.pending_exiters = NULL;
 	    erts_smp_runq_unlock(rq);
 	    handle_pending_exiters(pnd_xtrs);
 	    erts_smp_runq_lock(rq);
 	}
 
-	if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
 	    if (rq->check_balance_reds <= 0)
 		check_balance(rq);
 
@@ -9391,8 +9559,10 @@ Process *schedule(Process *p, int calls)
 
 	if (flags & (ERTS_RUNQ_FLG_CHK_CPU_BIND|ERTS_RUNQ_FLG_SUSPENDED)) {
 	    if (flags & ERTS_RUNQ_FLG_SUSPENDED) {
+		(void) ERTS_RUNQ_FLGS_UNSET_NOB(rq, ERTS_RUNQ_FLG_EXEC);
 		suspend_scheduler(esdp);
-		flags = ERTS_RUNQ_FLGS_GET_NOB(rq);
+		flags = ERTS_RUNQ_FLGS_SET_NOB(rq, ERTS_RUNQ_FLG_EXEC);
+		flags |= ERTS_RUNQ_FLG_EXEC;
 	    }
 	    if (flags & ERTS_RUNQ_FLG_CHK_CPU_BIND) {
 		flags = ERTS_RUNQ_FLGS_UNSET(rq, ERTS_RUNQ_FLG_CHK_CPU_BIND);
@@ -9407,24 +9577,20 @@ Process *schedule(Process *p, int calls)
 	    suspend_scheduler(esdp);
 #endif
 
-	{
+	if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
 	    erts_aint32_t aux_work;
-	    int leader_update = ERTS_SCHEDULER_IS_DIRTY(esdp) ? 0
-		: erts_thr_progress_update(esdp);
+	    int leader_update = erts_thr_progress_update(esdp);
 	    aux_work = erts_atomic32_read_acqb(&esdp->ssi->aux_work);
-	    if (aux_work | leader_update | ERTS_SCHED_FAIR) {
+	    if (aux_work | leader_update) {
 		erts_smp_runq_unlock(rq);
 		if (leader_update)
 		    erts_thr_progress_leader_update(esdp);
-		else if (ERTS_SCHED_FAIR)
-		  ERTS_SCHED_FAIR_YIELD();
 		if (aux_work)
 		    handle_aux_work(&esdp->aux_work_data, aux_work, 0);
 		erts_smp_runq_lock(rq);
 	    }
 
-	    ERTS_SMP_LC_ASSERT(ERTS_SCHEDULER_IS_DIRTY(esdp)
-			       || !erts_thr_progress_is_blocking());
+	    ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
 	}
 	ERTS_SMP_LC_ASSERT(erts_smp_lc_runq_is_locked(rq));
 
@@ -9483,8 +9649,11 @@ Process *schedule(Process *p, int calls)
 	    }
 #endif
 
+	    (void) ERTS_RUNQ_FLGS_UNSET(rq, ERTS_RUNQ_FLG_EXEC);
 	    scheduler_wait(&fcalls, esdp, rq);
-
+	    flags = ERTS_RUNQ_FLGS_SET_NOB(rq, ERTS_RUNQ_FLG_EXEC);
+	    flags |= ERTS_RUNQ_FLG_EXEC;
+            ERTS_MSACC_UPDATE_CACHE();
 #ifdef ERTS_SMP
 	    non_empty_runq(rq);
 #endif
@@ -9493,12 +9662,14 @@ Process *schedule(Process *p, int calls)
 	}
 	else if (!ERTS_SCHEDULER_IS_DIRTY(esdp) &&
 		 (fcalls > input_reductions &&
-		  prepare_for_sys_schedule(esdp, !0))) {
+		  prepare_for_sys_schedule(!0))) {
 	    ErtsMonotonicTime current_time;
 	    /*
 	     * Schedule system-level activities.
 	     */
 
+	    ERTS_MSACC_PUSH_STATE_CACHED_M();
+
 	    erts_smp_atomic32_set_relb(&function_calls, 0);
 	    fcalls = 0;
 
@@ -9506,7 +9677,9 @@ Process *schedule(Process *p, int calls)
 	    erts_sys_schedule_interrupt(0);
 #endif
 	    erts_smp_runq_unlock(rq);
+	    ERTS_MSACC_SET_STATE_CACHED_M(ERTS_MSACC_STATE_CHECK_IO);
 	    erl_sys_schedule(1);
+	    ERTS_MSACC_POP_STATE_M();
 
 	    current_time = erts_get_monotonic_time(esdp);
 	    if (current_time >= erts_next_timeout_time(esdp->next_tmo_ref))
@@ -9564,11 +9737,12 @@ Process *schedule(Process *p, int calls)
     pick_next_process: {
 	    erts_aint32_t psflg_band_mask;
 	    int prio_q;
-	    int qmask;
+	    int qmask, qbit;
 
 	    flags = ERTS_RUNQ_FLGS_GET_NOB(rq);
 	    qmask = (int) (flags & ERTS_RUNQ_FLGS_PROCS_QMASK);
-	    switch (qmask & -qmask) {
+	    qbit = qmask & -qmask;
+	    switch (qbit) {
 	    case MAX_BIT:
 		prio_q = PRIORITY_MAX;
 		break;
@@ -9584,9 +9758,12 @@ Process *schedule(Process *p, int calls)
 	    case 0:			/* No process at all */
 	    default:
 		ASSERT(qmask == 0);
+                ERTS_MSACC_SET_STATE_CACHED_M(ERTS_MSACC_STATE_OTHER);
 		goto check_activities_to_run;
 	    }
 
+            ERTS_MSACC_SET_STATE_CACHED_M(ERTS_MSACC_STATE_EMULATOR);
+
 	    BM_START_TIMER(system);
 
 	    /*
@@ -9596,20 +9773,11 @@ Process *schedule(Process *p, int calls)
 
 	    ASSERT(p); /* Wrong qmask in rq->flags? */
 
-	    psflg_band_mask = ~(((erts_aint32_t) 1) << (ERTS_PSFLGS_GET_PRQ_PRIO(state)
-							+ ERTS_PSFLGS_IN_PRQ_MASK_OFFSET));
-
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    ASSERT((state & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC)) !=
-		   (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC));
-	    if (state & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC)) {
-		ASSERT((ERTS_SCHEDULER_IS_DIRTY_CPU(esdp) && (state & ERTS_PSFLG_DIRTY_CPU_PROC)) ||
-		       (ERTS_SCHEDULER_IS_DIRTY_IO(esdp) && (state & ERTS_PSFLG_DIRTY_IO_PROC)));
-		if (!ERTS_SCHEDULER_IS_DIRTY(esdp) && !(state & ERTS_PSFLG_ACTIVE_SYS))
-		    goto pick_next_process;
-		state &= ~(ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q|ERTS_PSFLG_DIRTY_IO_PROC_IN_Q);
-	    }
-#endif
+	    if (ERTS_SCHEDULER_IS_DIRTY(esdp))
+		psflg_band_mask = ~((erts_aint32_t) 0);
+	    else
+		psflg_band_mask = ~(((erts_aint32_t) 1) << (ERTS_PSFLGS_GET_PRQ_PRIO(state)
+							    + ERTS_PSFLGS_IN_PRQ_MASK_OFFSET));
 
 	    if (!(state & ERTS_PSFLG_PROXY))
 		psflg_band_mask &= ~ERTS_PSFLG_IN_RUNQ;
@@ -9632,9 +9800,11 @@ Process *schedule(Process *p, int calls)
 			       | ERTS_PSFLG_RUNNING_SYS))) {
 		    tmp = state & (ERTS_PSFLG_SUSPENDED
 				   | ERTS_PSFLG_PENDING_EXIT
-				   | ERTS_PSFLG_ACTIVE_SYS);
+				   | ERTS_PSFLG_ACTIVE_SYS
+				   | ERTS_PSFLG_DIRTY_ACTIVE_SYS);
 		    if (tmp != ERTS_PSFLG_SUSPENDED) {
-			if (state & ERTS_PSFLG_ACTIVE_SYS)
+			if (state & (ERTS_PSFLG_ACTIVE_SYS
+				     | ERTS_PSFLG_DIRTY_ACTIVE_SYS))
 			    new |= ERTS_PSFLG_RUNNING_SYS;
 			else
 			    new |= ERTS_PSFLG_RUNNING;
@@ -9647,7 +9817,8 @@ Process *schedule(Process *p, int calls)
 				  | ERTS_PSFLG_FREE))
 			|| ((state & (ERTS_PSFLG_SUSPENDED
 				      | ERTS_PSFLG_PENDING_EXIT
-				      | ERTS_PSFLG_ACTIVE_SYS))
+				      | ERTS_PSFLG_ACTIVE_SYS
+				      | ERTS_PSFLG_DIRTY_ACTIVE_SYS))
 			    == ERTS_PSFLG_SUSPENDED)) {
 			if (state & ERTS_PSFLG_FREE)
 			    erts_proc_dec_refc(p);
@@ -9666,10 +9837,42 @@ Process *schedule(Process *p, int calls)
 
 	    esdp->current_process = p;
 
+
+	    reds = context_reds;
+
+#ifdef ERTS_SMP
+
+	    erts_smp_runq_unlock(rq);
+
+#ifdef ERTS_DIRTY_SCHEDULERS
+	    if (ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+#ifdef DEBUG
+		int old_dqbit;
+#endif
+		int dqbit = qbit;
+
+		if (rq == ERTS_DIRTY_CPU_RUNQ)
+		    dqbit <<= ERTS_PDSFLGS_IN_CPU_PRQ_MASK_OFFSET;
+		else {
+		    ASSERT(rq == ERTS_DIRTY_IO_RUNQ);
+		    dqbit <<= ERTS_PDSFLGS_IN_IO_PRQ_MASK_OFFSET;
+		}
+
+#ifdef DEBUG
+		old_dqbit = (int)
+#else
+		    (void)
+#endif
+		    erts_smp_atomic32_read_band_mb(&p->dirty_state, ~dqbit);
+		ASSERT(old_dqbit & dqbit);
+	    }
+#endif /* ERTS_DIRTY_SCHEDULERS */
+
+#endif /* ERTS_SMP */
+
 	}
 
 #ifdef ERTS_SMP
-	erts_smp_runq_unlock(rq);
 
 	if (flags & ERTS_RUNQ_FLG_PROTECTED)
 	    (void) ERTS_RUNQ_FLGS_UNSET(rq, ERTS_RUNQ_FLG_PROTECTED);
@@ -9678,6 +9881,8 @@ Process *schedule(Process *p, int calls)
 
 	erts_smp_proc_lock(p, ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_STATUS);
 
+	state = erts_smp_atomic32_read_nob(&p->state);
+
 	if (erts_sched_stat.enabled) {
 	    int prio;
 	    UWord old = ERTS_PROC_SCHED_ID(p,
@@ -9702,15 +9907,56 @@ Process *schedule(Process *p, int calls)
 	    erts_smp_spin_unlock(&erts_sched_stat.lock);
 	}
 
-	if (ERTS_PROC_PENDING_EXIT(p)) {
+	ASSERT(!p->scheduler_data);
+	p->scheduler_data = esdp;
+
+	state = erts_smp_atomic32_read_nob(&p->state);
+
+#ifdef ERTS_DIRTY_SCHEDULERS
+	if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+	    if (!!(state & ERTS_PSFLGS_DIRTY_WORK)
+		& !(state & ERTS_PSFLG_ACTIVE_SYS)) {
+		/* Migrate to dirty scheduler... */
+	    sunlock_sched_out_proc:
+		erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
+		p->fcalls = reds;
+		goto sched_out_proc;
+
+	    }
+	}
+	else {
+	    if (state & (ERTS_PSFLG_ACTIVE_SYS
+			 | ERTS_PSFLG_PENDING_EXIT
+			 | ERTS_PSFLG_EXITING)) {
+		/* Migrate to normal scheduler... */
+		goto sunlock_sched_out_proc;
+	    }
+	    if ((state & ERTS_PSFLG_DIRTY_ACTIVE_SYS)
+		&& rq == ERTS_DIRTY_IO_RUNQ) {
+		/* Migrate to dirty cpu scheduler... */
+		goto sunlock_sched_out_proc;
+	    }
+
+	    ASSERT((state & ERTS_PSFLG_DIRTY_ACTIVE_SYS)
+		   || *p->i == (BeamInstr) em_call_nif);
+
+	    ASSERT(rq == ERTS_DIRTY_CPU_RUNQ
+		   ? (state & (ERTS_PSFLG_DIRTY_CPU_PROC
+			       | ERTS_PSFLG_DIRTY_ACTIVE_SYS))
+		   : (rq == ERTS_DIRTY_IO_RUNQ
+		      && (state & ERTS_PSFLG_DIRTY_IO_PROC)));	    
+	}
+#endif
+
+	if (state & ERTS_PSFLG_PENDING_EXIT) {
 	    erts_handle_pending_exit(p,
 				     ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_STATUS);
 	    state = erts_smp_atomic32_read_nob(&p->state);
 	}
-	ASSERT(!p->scheduler_data);
-	p->scheduler_data = esdp;
-#endif
-	reds = context_reds;
+
+#endif /* ERTS_SMP */
+
+	p->fcalls = reds;
 
 	if (IS_TRACED(p)) {
 	    if (state & ERTS_PSFLG_EXITING) {
@@ -9739,7 +9985,8 @@ Process *schedule(Process *p, int calls)
 	    reds -= execute_sys_tasks(p, &state, reds);
 	    if (reds <= 0
 #ifdef ERTS_DIRTY_SCHEDULERS
-		|| (state & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC))
+		|| ERTS_SCHEDULER_IS_DIRTY(esdp)
+		|| (state & ERTS_PSFLGS_DIRTY_WORK)
 #endif
 		) {
 		p->fcalls = reds;
@@ -9772,13 +10019,13 @@ Process *schedule(Process *p, int calls)
 	    }
 	}
 
-	if (!(state & ERTS_PSFLG_EXITING)
-	    && ((FLAGS(p) & F_FORCE_GC)
-		|| (MSO(p).overhead > BIN_VHEAP_SZ(p)))) {
-	    reds -= erts_garbage_collect(p, 0, p->arg_reg, p->arity);
-	    if (reds <= 0) {
-		p->fcalls = reds;
-		goto sched_out_proc;
+	if (ERTS_IS_GC_DESIRED(p)) {
+	    if (!(state & ERTS_PSFLG_EXITING) && !(p->flags & F_DISABLE_GC)) {
+		reds -= erts_garbage_collect_nobump(p, 0, p->arg_reg, p->arity);
+		if (reds <= 0) {
+		    p->fcalls = reds;
+		    goto sched_out_proc;
+		}
 	    }
 	}
 
@@ -9787,7 +10034,6 @@ Process *schedule(Process *p, int calls)
 	    proxy_p = NULL;
 	}
 	    
-	p->fcalls = reds;
 	ERTS_SMP_CHK_HAVE_ONLY_MAIN_PROC_LOCK(p);
 
 	/* Never run a suspended process */
@@ -9818,7 +10064,7 @@ notify_sys_task_executed(Process *c_p, ErtsProcSysTask *st, Eterm st_result)
     if (rp) {
 	ErtsProcLocks rp_locks;
 	ErlOffHeap *ohp;
-	ErlHeapFragment* bp;
+	ErtsMessage *mp;
 	Eterm *hp, msg, req_id, result;
 	Uint st_result_sz, hsz;
 #ifdef DEBUG
@@ -9830,11 +10076,7 @@ notify_sys_task_executed(Process *c_p, ErtsProcSysTask *st, Eterm st_result)
 	st_result_sz = is_immed(st_result) ? 0 : size_object(st_result);
 	hsz = st->req_id_sz + st_result_sz + 4 /* 3-tuple */;
 
-	hp = erts_alloc_message_heap(hsz,
-				     &bp,
-				     &ohp,
-				     rp,
-				     &rp_locks);
+	mp = erts_alloc_message_heap(rp, &rp_locks, hsz, &hp, &ohp);
 
 #ifdef DEBUG
 	hp_start = hp;
@@ -9859,7 +10101,7 @@ notify_sys_task_executed(Process *c_p, ErtsProcSysTask *st, Eterm st_result)
 	ASSERT(hp_start + hsz == hp);
 #endif
 
-	erts_queue_message(rp, &rp_locks, bp, msg, NIL);
+	erts_queue_message(rp, &rp_locks, mp, msg, NIL);
 
 	if (c_p == rp)
 	    rp_locks &= ~ERTS_PROC_LOCK_MAIN;
@@ -10061,10 +10303,10 @@ execute_sys_tasks(Process *c_p, erts_aint32_t *statep, int in_reds)
 	    else {
 		if (!garbage_collected) {
 		    FLAGS(c_p) |= F_NEED_FULLSWEEP;
-		    reds += erts_garbage_collect(c_p,
-						 0,
-						 c_p->arg_reg,
-						 c_p->arity);
+		    reds += erts_garbage_collect_nobump(c_p,
+							0,
+							c_p->arg_reg,
+							c_p->arity);
 		    garbage_collected = 1;
 		}
 		st_res = am_true;
@@ -10073,7 +10315,7 @@ execute_sys_tasks(Process *c_p, erts_aint32_t *statep, int in_reds)
 	case ERTS_PSTT_CPC:
 	    st_res = erts_check_process_code(c_p,
 					     st->arg[0],
-					     st->arg[1] == am_true,
+                                             unsigned_val(st->arg[1]),
 					     &reds);
 	    if (is_non_value(st_res)) {
 		/* Needed gc, but gc was disabled */
@@ -10081,6 +10323,10 @@ execute_sys_tasks(Process *c_p, erts_aint32_t *statep, int in_reds)
 		st = NULL;
 	    }
 	    break;
+	case ERTS_PSTT_COHMQ:
+	    reds += erts_complete_off_heap_message_queue_change(c_p);
+	    st_res = am_true;
+	    break;
 	default:
 	    ERTS_INTERNAL_ERROR("Invalid process sys task type");
 	    st_res = am_false;
@@ -10123,6 +10369,9 @@ cleanup_sys_tasks(Process *c_p, erts_aint32_t in_state, int in_reds)
 	case ERTS_PSTT_CPC:
 	    st_res = am_false;
 	    break;
+	case ERTS_PSTT_COHMQ:
+	    st_res = am_false;
+	    break;
 	default:
 	    ERTS_INTERNAL_ERROR("Invalid process sys task type");
 	    st_res = am_false;
@@ -10141,10 +10390,8 @@ BIF_RETTYPE
 erts_internal_request_system_task_3(BIF_ALIST_3)
 {
     Process *rp = erts_proc_lookup(BIF_ARG_1);
-    ErtsProcSysTaskQs *stqs, *free_stqs = NULL;
     ErtsProcSysTask *st = NULL;
-    erts_aint32_t prio, rp_state;
-    int rp_locked;
+    erts_aint32_t prio;
     Eterm noproc_res, req_type;
 
     if (!rp && !is_internal_pid(BIF_ARG_1)) {
@@ -10201,7 +10448,6 @@ erts_internal_request_system_task_3(BIF_ALIST_3)
 	}
 	st = erts_alloc(ERTS_ALC_T_PROC_SYS_TSK,
 			ERTS_PROC_SYS_TASK_SIZE(tot_sz));
-	st->next = st->prev = st; /* Prep for empty prio queue */
 	ERTS_INIT_OFF_HEAP(&st->off_heap);
 	hp = &st->heap[0];
 
@@ -10233,7 +10479,7 @@ erts_internal_request_system_task_3(BIF_ALIST_3)
     case am_check_process_code:
 	if (is_not_atom(st->arg[0]))
 	    goto badarg;
-	if (st->arg[1] != am_true && st->arg[1] != am_false)
+	if (is_not_small(st->arg[1]) || (unsigned_val(st->arg[1]) & ~ERTS_CPC_ALL))
 	    goto badarg;
 	noproc_res = am_false;
 	st->type = ERTS_PSTT_CPC;
@@ -10245,95 +10491,11 @@ erts_internal_request_system_task_3(BIF_ALIST_3)
 	goto badarg;
     }
 
-    rp_state = erts_smp_atomic32_read_nob(&rp->state);
-
-    rp_locked = 0;
-
-    free_stqs = NULL;
-    if (rp_state & ERTS_PSFLG_ACTIVE_SYS)
-	stqs = NULL;
-    else {
-    alloc_qs:
-	stqs = proc_sys_task_queues_alloc();
-	stqs->qmask = 1 << prio;
-	stqs->ncount = 0;
-	stqs->q[PRIORITY_MAX] = NULL;
-	stqs->q[PRIORITY_HIGH] = NULL;
-	stqs->q[PRIORITY_NORMAL] = NULL;
-	stqs->q[PRIORITY_LOW] = NULL;
-	stqs->q[prio] = st;
-    }
-
-    if (!rp_locked) {
-	rp_locked = 1;
-	erts_smp_proc_lock(rp, ERTS_PROC_LOCK_STATUS);
-
-	rp_state = erts_smp_atomic32_read_nob(&rp->state);
-	if (rp_state & ERTS_PSFLG_EXITING) {
-	    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_STATUS);
-	    rp = NULL;
-	    free_stqs = stqs;
-	    goto noproc;
-	}
-    }
-
-    if (!rp->sys_task_qs) {
-	if (stqs)
-	    rp->sys_task_qs = stqs;
-	else
-	    goto alloc_qs;
-    }
-    else {
-	if (stqs)
-	    free_stqs = stqs;
-	stqs = rp->sys_task_qs;
-	if (!stqs->q[prio]) {
-	    stqs->q[prio] = st;
-	    stqs->qmask |= 1 << prio;
-	}
-	else {
-	    st->next = stqs->q[prio];
-	    st->prev = stqs->q[prio]->prev;
-	    st->next->prev = st;
-	    st->prev->next = st;
-	    ASSERT(stqs->qmask & (1 << prio));
-	}
-    }
-
-    if (ERTS_PSFLGS_GET_ACT_PRIO(rp_state) > prio) {
-	erts_aint32_t n, a, e;
-	/* Need to elevate actual prio */
-
-	a = rp_state;
-	do {
-	    if (ERTS_PSFLGS_GET_ACT_PRIO(a) <= prio) {
-		n = a;
-		break;
-	    }
-	    n = e = a;
-	    n &= ~ERTS_PSFLGS_ACT_PRIO_MASK;
-	    n |= (prio << ERTS_PSFLGS_ACT_PRIO_OFFSET);
-	    a = erts_smp_atomic32_cmpxchg_nob(&rp->state, n, e);    
-	} while (a != e);
-	rp_state = n;
+    if (!schedule_process_sys_task(rp, prio, st)) {
+    noproc:
+	notify_sys_task_executed(BIF_P, st, noproc_res);
     }
 
-    /*
-     * schedule_process_sys_task() unlocks status
-     * lock on process.
-     */
-    schedule_process_sys_task(rp, rp_state, NULL);
-
-    if (free_stqs)
-	proc_sys_task_queues_free(free_stqs);
-
-    BIF_RET(am_ok);
-
-noproc:
-
-    notify_sys_task_executed(BIF_P, st, noproc_res);
-    if (free_stqs)
-	proc_sys_task_queues_free(free_stqs);
     BIF_RET(am_ok);
 
 badarg:
@@ -10342,11 +10504,35 @@ badarg:
 	erts_cleanup_offheap(&st->off_heap);
 	erts_free(ERTS_ALC_T_PROC_SYS_TSK, st);
     }
-    if (free_stqs)
-	proc_sys_task_queues_free(free_stqs);
     BIF_ERROR(BIF_P, BADARG);
 }
 
+void
+erts_schedule_complete_off_heap_message_queue_change(Eterm pid)
+{
+    Process *rp = erts_proc_lookup(pid);
+    if (rp) {
+	ErtsProcSysTask *st;
+	erts_aint32_t state;
+	int i;
+
+	st = erts_alloc(ERTS_ALC_T_PROC_SYS_TSK,
+			ERTS_PROC_SYS_TASK_SIZE(0));
+	st->type = ERTS_PSTT_COHMQ;
+	st->requester = NIL;
+	st->reply_tag = NIL;
+	st->req_id = NIL;
+	st->req_id_sz = 0;
+	for (i = 0; i < ERTS_MAX_PROC_SYS_TASK_ARGS; i++)
+	    st->arg[i] = NIL;
+	ERTS_INIT_OFF_HEAP(&st->off_heap);
+	state = erts_smp_atomic32_read_nob(&rp->state);
+
+	if (!schedule_process_sys_task(rp, ERTS_PSFLGS_GET_USR_PRIO(state), st))
+	    erts_free(ERTS_ALC_T_PROC_SYS_TSK, st);
+    }
+}
+
 static void
 save_gc_task(Process *c_p, ErtsProcSysTask *st, int prio)
 {
@@ -10732,6 +10918,9 @@ static void early_init_process_struct(void *varg, Eterm data)
     Process *proc = arg->proc;
 
     proc->common.id = make_internal_pid(data);
+#ifdef ERTS_DIRTY_SCHEDULERS
+    erts_smp_atomic32_init_nob(&proc->dirty_state, 0);
+#endif
     erts_smp_atomic32_init_relb(&proc->state, arg->state);
 
 #ifdef ERTS_SMP
@@ -10792,6 +10981,7 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
 		   Eterm args,	/* Arguments for function (must be well-formed list). */
 		   ErlSpawnOpts* so) /* Options for spawn. */
 {
+    Uint flags = 0;
     ErtsRunQueue *rq = NULL;
     Process *p;
     Sint arity;			/* Number of arguments. */
@@ -10801,6 +10991,10 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     Eterm res = THE_NON_VALUE;
     erts_aint32_t state = 0;
     erts_aint32_t prio = (erts_aint32_t) PRIORITY_NORMAL;
+#ifdef SHCOPY_SPAWN
+    erts_shcopy_t info;
+    INITIALIZE_SHCOPY(info);
+#endif
 
 #ifdef ERTS_SMP
     erts_smp_proc_lock(parent, ERTS_PROC_LOCKS_ALL_MINOR);
@@ -10829,6 +11023,15 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     state |= (((prio & ERTS_PSFLGS_PRIO_MASK) << ERTS_PSFLGS_ACT_PRIO_OFFSET)
 	      | ((prio & ERTS_PSFLGS_PRIO_MASK) << ERTS_PSFLGS_USR_PRIO_OFFSET));
 
+    if (so->flags & SPO_OFF_HEAP_MSGQ) {
+	state |= ERTS_PSFLG_OFF_HEAP_MSGQ;
+	flags |= F_OFF_HEAP_MSGQ;
+    }
+    else if (so->flags & SPO_ON_HEAP_MSGQ) {
+	state |= ERTS_PSFLG_ON_HEAP_MSGQ;
+	flags |= F_ON_HEAP_MSGQ;
+    }
+
     if (!rq)
 	rq = erts_get_runq_proc(parent);
 
@@ -10847,11 +11050,15 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     BM_COUNT(processes_spawned);
 
     BM_SWAP_TIMER(system,size);
+#ifdef SHCOPY_SPAWN
+    arg_size = copy_shared_calculate(args, &info);
+#else
     arg_size = size_object(args);
+#endif
     BM_SWAP_TIMER(size,system);
     heap_need = arg_size;
 
-    p->flags = erts_default_process_flags;
+    p->flags = flags;
 
     p->static_flags = 0;
     if (so->flags & SPO_SYSTEM_PROC)
@@ -10900,12 +11107,13 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     p->stop = p->hend = p->heap + sz;
     p->htop = p->heap;
     p->heap_sz = sz;
+    p->abandoned_heap = NULL;
+    p->live_hf_end = ERTS_INVALID_HFRAG_PTR;
     p->catches = 0;
 
     p->bin_vheap_sz     = p->min_vheap_size;
     p->bin_old_vheap_sz = p->min_vheap_size;
     p->bin_old_vheap    = 0;
-    p->bin_vheap_mature = 0;
 
     p->sys_task_qs = NULL;
 
@@ -10924,7 +11132,12 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     BM_MESSAGE(args,p,parent);
     BM_START_TIMER(system);
     BM_SWAP_TIMER(system,copy);
+#ifdef SHCOPY_SPAWN
+    p->arg_reg[2] = copy_shared_perform(args, arg_size, &info, &p->htop, &p->off_heap);
+    DESTROY_SHCOPY(info);
+#else
     p->arg_reg[2] = copy_struct(args, arg_size, &p->htop, &p->off_heap);
+#endif
     BM_MESSAGE_COPIED(arg_size);
     BM_SWAP_TIMER(copy,system);
     p->arity = 3;
@@ -10970,6 +11183,7 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     p->accessor_bif_timers = NULL;
 #endif
     p->mbuf = NULL;
+    p->msg_frag = NULL;
     p->mbuf_sz = 0;
     p->psd = NULL;
     p->dictionary = NULL;
@@ -11105,6 +11319,8 @@ void erts_init_empty_process(Process *p)
     p->stop = NULL;
     p->hend = NULL;
     p->heap = NULL;
+    p->abandoned_heap = NULL;
+    p->live_hf_end = ERTS_INVALID_HFRAG_PTR;
     p->gen_gcs = 0;
     p->max_gen_gcs = 0;
     p->min_heap_size = 0;
@@ -11125,7 +11341,6 @@ void erts_init_empty_process(Process *p)
     p->bin_old_vheap_sz = BIN_VH_MIN_SIZE;
     p->bin_old_vheap = 0;
     p->sys_task_qs = NULL;
-    p->bin_vheap_mature = 0;
     ERTS_PTMR_INIT(p);
     p->next = NULL;
     p->off_heap.first = NULL;
@@ -11137,6 +11352,7 @@ void erts_init_empty_process(Process *p)
     p->old_htop = NULL;
     p->old_heap = NULL;
     p->mbuf = NULL;
+    p->msg_frag = NULL;
     p->mbuf_sz = 0;
     p->psd = NULL;
     ERTS_P_MONITORS(p) = NULL;
@@ -11194,6 +11410,9 @@ void erts_init_empty_process(Process *p)
     p->last_old_htop = NULL;
 #endif
 
+#ifdef ERTS_DIRTY_SCHEDULERS
+    erts_smp_atomic32_init_nob(&p->dirty_state, 0);
+#endif
     erts_smp_atomic32_init_nob(&p->state, (erts_aint32_t) PRIORITY_NORMAL);
 
 #ifdef ERTS_SMP
@@ -11225,6 +11444,8 @@ erts_debug_verify_clean_empty_process(Process* p)
     ASSERT(p->htop == NULL);
     ASSERT(p->stop == NULL);
     ASSERT(p->hend == NULL);
+    ASSERT(p->abandoned_heap == NULL);
+    ASSERT(p->live_hf_end == ERTS_INVALID_HFRAG_PTR);
     ASSERT(p->heap == NULL);
     ASSERT(p->common.id == ERTS_INVALID_PID);
     ASSERT(ERTS_TRACER_PROC(p) == NIL);
@@ -11302,9 +11523,10 @@ erts_cleanup_empty_process(Process* p)
 static void
 delete_process(Process* p)
 {
-    ErlMessage* mp;
-
+    Eterm *heap;
     VERBOSE(DEBUG_PROCESSES, ("Removing process: %T\n",p->common.id));
+    VERBOSE(DEBUG_SHCOPY, ("[pid=%T] delete process: %p %p %p %p\n", p->common.id,
+                           HEAP_START(p), HEAP_END(p), OLD_HEAP(p), OLD_HEND(p)));
 
     /* Cleanup psd */
 
@@ -11328,16 +11550,17 @@ delete_process(Process* p)
      * Release heaps. Clobber contents in DEBUG build.
      */
 
-
-#ifdef DEBUG
-    sys_memset(p->heap, DEBUG_BAD_BYTE, p->heap_sz*sizeof(Eterm));
-#endif
-
 #ifdef HIPE
     hipe_delete_process(&p->hipe);
 #endif
 
-    ERTS_HEAP_FREE(ERTS_ALC_T_HEAP, (void*) p->heap, p->heap_sz*sizeof(Eterm));
+    heap = p->abandoned_heap ? p->abandoned_heap : p->heap;
+
+#ifdef DEBUG
+    sys_memset(heap, DEBUG_BAD_BYTE, p->heap_sz*sizeof(Eterm));
+#endif
+
+    ERTS_HEAP_FREE(ERTS_ALC_T_HEAP, (void*) heap, p->heap_sz*sizeof(Eterm));
     if (p->old_heap != NULL) {
 
 #ifdef DEBUG
@@ -11356,27 +11579,14 @@ delete_process(Process* p)
 	free_message_buffer(p->mbuf);
     }
 
+    if (p->msg_frag)
+	erts_cleanup_messages(p->msg_frag);
+
     erts_erase_dicts(p);
 
     /* free all pending messages */
-    mp = p->msg.first;
-    while(mp != NULL) {
-	ErlMessage* next_mp = mp->next;
-	if (mp->data.attached) {
-	    if (is_value(mp->m[0]))
-		free_message_buffer(mp->data.heap_frag);
-	    else {
-		if (is_not_nil(mp->m[1])) {
-		    ErlHeapFragment *heap_frag;
-		    heap_frag = (ErlHeapFragment *) mp->data.dist_ext->ext_endp;
-		    erts_cleanup_offheap(&heap_frag->off_heap);
-		}
-		erts_free_dist_ext_copy(mp->data.dist_ext);
-	    }
-	}
-	free_message(mp);
-	mp = next_mp;
-    }
+    erts_cleanup_messages(p->msg.first);
+    p->msg.first = NULL;
 
     ASSERT(!p->nodes_monitors);
     ASSERT(!p->suspend_monitors);
@@ -11395,7 +11605,9 @@ set_proc_exiting(Process *p,
     ERTS_SMP_LC_ASSERT(erts_proc_lc_my_proc_locks(p) == ERTS_PROC_LOCKS_ALL);
 
     enqueue = change_proc_schedule_state(p,
-					 ERTS_PSFLG_SUSPENDED|ERTS_PSFLG_PENDING_EXIT,
+					 (ERTS_PSFLG_SUSPENDED
+					  | ERTS_PSFLG_PENDING_EXIT
+					  | ERTS_PSFLGS_DIRTY_WORK),
 					 ERTS_PSFLG_EXITING|ERTS_PSFLG_ACTIVE,
 					 &state,
 					 &enq_prio,
@@ -11429,10 +11641,7 @@ set_proc_exiting(Process *p,
     }
 #endif
 
-    if (enqueue)
-	add2runq(enqueue > 0 ? p : make_proxy_proc(NULL, p, enq_prio),
-		 state,
-		 enq_prio);
+    add2runq(enqueue, enq_prio, p, state, NULL);
 }
 
 static ERTS_INLINE erts_aint32_t
@@ -11535,6 +11744,11 @@ save_pending_exiter(Process *p)
     else
         rq = esdp->run_queue;
 
+#ifdef ERTS_DIRTY_SCHEDULERS
+    if (ERTS_RUNQ_IX_IS_DIRTY(rq->ix))
+	rq = ERTS_RUNQ_IX(0); /* Handle on ordinary scheduler */
+#endif
+
     plp = proclist_create(p);
 
     erts_smp_runq_lock(rq);
@@ -11544,13 +11758,8 @@ save_pending_exiter(Process *p)
     non_empty_runq(rq);
 
     erts_smp_runq_unlock(rq);
-#ifdef ERTS_DIRTY_SCHEDULERS
-    if (ERTS_RUNQ_IX_IS_DIRTY(rq->ix))
-	wake_dirty_schedulers(rq, 0);
-    else
-#endif
-	wake_scheduler(rq);
 
+    wake_scheduler(rq);
 }
 
 #endif
@@ -11564,35 +11773,46 @@ static ERTS_INLINE void
 send_exit_message(Process *to, ErtsProcLocks *to_locksp,
 		  Eterm exit_term, Uint term_size, Eterm token)
 {
-    if (token == NIL 
-#ifdef USE_VM_PROBES
-	|| token == am_have_dt_utag
-#endif
-	) {
-	Eterm* hp;
-	Eterm mess;
-	ErlHeapFragment* bp;
-	ErlOffHeap *ohp;
-
-	hp = erts_alloc_message_heap(term_size, &bp, &ohp, to, to_locksp);
+    ErtsMessage *mp;
+    ErlOffHeap *ohp;
+    Eterm* hp;
+    Eterm mess;
+#ifdef SHCOPY_SEND
+    erts_shcopy_t info;
+#endif
+
+    if (!have_seqtrace(token)) {
+#ifdef SHCOPY_SEND
+        INITIALIZE_SHCOPY(info);
+        term_size = copy_shared_calculate(exit_term, &info);
+	mp = erts_alloc_message_heap(to, to_locksp, term_size, &hp, &ohp);
+        mess = copy_shared_perform(exit_term, term_size, &info, &hp, ohp);
+        DESTROY_SHCOPY(info);
+#else
+	mp = erts_alloc_message_heap(to, to_locksp, term_size, &hp, &ohp);
 	mess = copy_struct(exit_term, term_size, &hp, ohp);
-	erts_queue_message(to, to_locksp, bp, mess, NIL);
+#endif
+	erts_queue_message(to, to_locksp, mp, mess, NIL);
     } else {
-	ErlHeapFragment* bp;
-	Eterm* hp;
-	Eterm mess;
 	Eterm temp_token;
 	Uint sz_token;
 
 	ASSERT(is_tuple(token));
 	sz_token = size_object(token);
-	bp = new_message_buffer(term_size+sz_token);
-	hp = bp->mem;
-	mess = copy_struct(exit_term, term_size, &hp, &bp->off_heap);
+#ifdef SHCOPY_SEND
+        INITIALIZE_SHCOPY(info);
+        term_size = copy_shared_calculate(exit_term, &info);
+	mp = erts_alloc_message_heap(to, to_locksp, term_size+sz_token, &hp, &ohp);
+        mess = copy_shared_perform(exit_term, term_size, &info, &hp, ohp);
+        DESTROY_SHCOPY(info);
+#else
+	mp = erts_alloc_message_heap(to, to_locksp, term_size+sz_token, &hp, &ohp);
+	mess = copy_struct(exit_term, term_size, &hp, ohp);
+#endif
 	/* the trace token must in this case be updated by the caller */
 	seq_trace_output(token, mess, SEQ_TRACE_SEND, to->common.id, NULL);
-	temp_token = copy_struct(token, sz_token, &hp, &bp->off_heap);
-	erts_queue_message(to, to_locksp, bp, mess, temp_token);
+	temp_token = copy_struct(token, sz_token, &hp, ohp);
+	erts_queue_message(to, to_locksp, mp, mess, temp_token);
     }
 }
 
@@ -11701,11 +11921,7 @@ send_exit_signal(Process *c_p,		/* current process if and only
 
     if ((state & ERTS_PSFLG_TRAP_EXIT)
 	&& (reason != am_kill || (flags & ERTS_XSIG_FLG_IGN_KILL))) {
-	if (is_not_nil(token) 
-#ifdef USE_VM_PROBES
-	    && token != am_have_dt_utag
-#endif
-	    && token_update)
+        if (have_seqtrace(token) && token_update)
 	    seq_trace_update_send(token_update);
 	if (is_value(exit_tuple))
 	    send_exit_message(rp, rp_locks, exit_tuple, exit_tuple_sz, token);
@@ -12538,7 +12754,7 @@ stack_element_dump(int to, void *to_arg, Eterm* sp, int yreg)
     }
 
     if (is_CP(x)) {
-        erts_print(to, to_arg, "Return addr %p (", (Eterm *) EXPAND_POINTER(x));
+        erts_print(to, to_arg, "Return addr %p (", (Eterm *) x);
         print_function_from_pc(to, to_arg, cp_val(x));
         erts_print(to, to_arg, ")\n");
         yreg = 0;