Merge branch 'rickard/ds-sched-suspend'

* rickard/ds-sched-suspend:
  Improved scheduler suspend functionality

6 files changed, 1147 insertions, 1262 deletions

diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index dca8b503bf..169b071cd7 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -125,7 +125,9 @@ atom binary_longest_suffix_trap
 atom binary_to_list_continue
 atom binary_to_term_trap
 atom block
+atom block_normal
 atom blocked
+atom blocked_normal
 atom bm
 atom bnot
 atom bor
@@ -190,7 +192,9 @@ atom dexit
 atom depth
 atom dgroup_leader
 atom dictionary
+atom dirty_cpu
 atom dirty_cpu_schedulers_online
+atom dirty_io
 atom disable_trace
 atom disabled
 atom display_items
@@ -305,6 +309,7 @@ atom index
 atom infinity
 atom info
 atom info_msg
+atom init
 atom initial_call
 atom input
 atom internal
@@ -612,6 +617,7 @@ atom use_stdio
 atom used
 atom utf8
 atom unblock
+atom unblock_normal
 atom uniq
 atom unless_suspending
 atom unloaded
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index 6ab75496a0..37bb28c6f8 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -4197,22 +4197,33 @@ BIF_RETTYPE system_flag_2(BIF_ALIST_2)
     Sint n;
 
     if (BIF_ARG_1 == am_multi_scheduling) {
-	if (BIF_ARG_2 == am_block || BIF_ARG_2 == am_unblock) {
+	if (BIF_ARG_2 == am_block || BIF_ARG_2 == am_unblock
+	    || BIF_ARG_2 == am_block_normal || BIF_ARG_2 == am_unblock_normal) {
 #ifndef ERTS_SMP
 	    BIF_RET(am_disabled);
 #else
+	    int block = (BIF_ARG_2 == am_block
+			 || BIF_ARG_2 == am_block_normal);
+	    int normal = (BIF_ARG_2 == am_block_normal
+			  || BIF_ARG_2 == am_unblock_normal);
 	    if (erts_no_schedulers == 1)
 		BIF_RET(am_disabled);
 	    else {
 		switch (erts_block_multi_scheduling(BIF_P,
 						    ERTS_PROC_LOCK_MAIN,
-						    BIF_ARG_2 == am_block,
+						    block,
+						    normal,
 						    0)) {
 		case ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED:
 		    BIF_RET(am_blocked);
+		case ERTS_SCHDLR_SSPND_DONE_NMSCHED_BLOCKED:
+		    BIF_RET(am_blocked_normal);
 		case ERTS_SCHDLR_SSPND_YIELD_DONE_MSCHED_BLOCKED:
 		    ERTS_BIF_YIELD_RETURN_X(BIF_P, am_blocked,
 					    am_multi_scheduling);
+		case ERTS_SCHDLR_SSPND_YIELD_DONE_NMSCHED_BLOCKED:
+		    ERTS_BIF_YIELD_RETURN_X(BIF_P, am_blocked_normal,
+					    am_multi_scheduling);
 		case ERTS_SCHDLR_SSPND_DONE:
 		    BIF_RET(am_enabled);
 		case ERTS_SCHDLR_SSPND_YIELD_RESTART:
@@ -4245,11 +4256,7 @@ BIF_RETTYPE system_flag_2(BIF_ALIST_2)
 	switch (erts_set_schedulers_online(BIF_P,
 					   ERTS_PROC_LOCK_MAIN,
 					   signed_val(BIF_ARG_2),
-					   &old_no
-#ifdef ERTS_DIRTY_SCHEDULERS
-					   , 0
-#endif
-					   )) {
+					   &old_no, 0)) {
 	case ERTS_SCHDLR_SSPND_DONE:
 	    BIF_RET(make_small(old_no));
 	case ERTS_SCHDLR_SSPND_YIELD_RESTART:
@@ -4619,29 +4626,27 @@ BIF_RETTYPE erts_internal_cmp_term_2(BIF_ALIST_2) {
 /*
  * Processes doing yield on return in a bif ends up in bif_return_trap().
  */
-static BIF_RETTYPE bif_return_trap(
-#ifdef DEBUG
-    BIF_ALIST_2
-#else
-    BIF_ALIST_1
-#endif
-    )
+static BIF_RETTYPE bif_return_trap(BIF_ALIST_2)
 {
-#ifdef DEBUG
+    Eterm res = BIF_ARG_1;
+
     switch (BIF_ARG_2) {
-    case am_multi_scheduling:
 #ifdef ERTS_SMP
-	erts_dbg_multi_scheduling_return_trap(BIF_P, BIF_ARG_1);
-#endif
-	break;
-    case am_schedulers_online:
+    case am_multi_scheduling: {
+	int msb = erts_is_multi_scheduling_blocked();
+	if (msb > 0)
+	    res = am_blocked;
+	else if (msb < 0)
+	    res = am_blocked_normal;
+	else
+	    ERTS_INTERNAL_ERROR("Unexpected multi scheduling block state");
 	break;
+    }
+#endif
     default:
 	break;
     }
-#endif
-
-    BIF_RET(BIF_ARG_1);
+    BIF_RET(res);
 }
 
 /*
@@ -4746,17 +4751,12 @@ void erts_init_bif(void)
     erts_smp_atomic_init_nob(&erts_dead_ports_ptr, (erts_aint_t) NULL);
 
     /*
-     * bif_return_trap/1 is a hidden BIF that bifs that need to
-     * yield the calling process traps to. The only thing it does:
-     * return the value passed as argument.
+     * bif_return_trap/2 is a hidden BIF that bifs that need to
+     * yield the calling process traps to.
      */
-    erts_init_trap_export(&bif_return_trap_export, am_erlang, am_bif_return_trap,
-#ifdef DEBUG
-		     2
-#else
-		     1
-#endif
-		     , &bif_return_trap);
+    erts_init_trap_export(&bif_return_trap_export,
+			  am_erlang, am_bif_return_trap, 2,
+			  &bif_return_trap);
 
     erts_await_result = erts_export_put(am_erts_internal,
 					am_await_result,
diff --git a/erts/emulator/beam/bif.h b/erts/emulator/beam/bif.h
index a62eddf36b..46af552b39 100644
--- a/erts/emulator/beam/bif.h
+++ b/erts/emulator/beam/bif.h
@@ -338,37 +338,20 @@ do {							\
  } while(0)
 
 extern Export bif_return_trap_export;
-#ifdef DEBUG
-#define ERTS_BIF_PREP_YIELD_RETURN_X(RET, P, VAL, DEBUG_VAL)		\
+#define ERTS_BIF_PREP_YIELD_RETURN_X(RET, P, VAL, OP)			\
 do {									\
     ERTS_VBUMP_ALL_REDS(P);						\
-    ERTS_BIF_PREP_TRAP2(RET, &bif_return_trap_export, (P), (VAL),	\
-			(DEBUG_VAL));					\
+    ERTS_BIF_PREP_TRAP2(RET, &bif_return_trap_export, (P), (VAL), (OP));\
 } while (0)
-#else
-#define ERTS_BIF_PREP_YIELD_RETURN_X(RET, P, VAL, DEBUG_VAL)		\
-do {									\
-    ERTS_VBUMP_ALL_REDS(P);						\
-    ERTS_BIF_PREP_TRAP1(RET, &bif_return_trap_export, (P), (VAL));	\
-} while (0)
-#endif
 
 #define ERTS_BIF_PREP_YIELD_RETURN(RET, P, VAL) \
   ERTS_BIF_PREP_YIELD_RETURN_X(RET, (P), (VAL), am_undefined)
 
-#ifdef DEBUG
-#define ERTS_BIF_YIELD_RETURN_X(P, VAL, DEBUG_VAL)			\
+#define ERTS_BIF_YIELD_RETURN_X(P, VAL, OP)				\
 do {									\
     ERTS_VBUMP_ALL_REDS(P);						\
-    BIF_TRAP2(&bif_return_trap_export, (P), (VAL), (DEBUG_VAL));	\
+    BIF_TRAP2(&bif_return_trap_export, (P), (VAL), (OP));		\
 } while (0)
-#else
-#define ERTS_BIF_YIELD_RETURN_X(P, VAL, DEBUG_VAL)			\
-do {									\
-    ERTS_VBUMP_ALL_REDS(P);						\
-    BIF_TRAP1(&bif_return_trap_export, (P), (VAL));			\
-} while (0)
-#endif
 
 #define ERTS_BIF_RETURN_YIELD(P) ERTS_VBUMP_ALL_REDS((P))
 
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 39eb257c2c..8c748c9bf7 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -320,13 +320,11 @@ erts_print_system_version(int to, void *arg, Process *c_p)
     char *ov = otp_version;
 #ifdef ERTS_SMP
     Uint total, online, active;
-#ifdef ERTS_DIRTY_SCHEDULERS
     Uint dirty_cpu, dirty_cpu_onln, dirty_io;
 
-    (void) erts_schedulers_state(&total, &online, &active, &dirty_cpu, &dirty_cpu_onln, &dirty_io, 0);
-#else
-    (void) erts_schedulers_state(&total, &online, &active, NULL, NULL, NULL, 0);
-#endif
+    erts_schedulers_state(&total, &online, &active,
+			  &dirty_cpu, &dirty_cpu_onln, NULL,
+			  &dirty_io, NULL);
 #endif
     for (i = 0; i < sizeof(otp_version)-4; i++) {
 	if (ov[i] == '-' && ov[i+1] == 'r' && ov[i+2] == 'c')
@@ -2044,12 +2042,18 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 #ifndef ERTS_SMP
 	BIF_RET(am_disabled);
 #else
+#ifndef ERTS_DIRTY_SCHEDULERS
 	if (erts_no_schedulers == 1)
 	    BIF_RET(am_disabled);
-	else {
-	    BIF_RET(erts_is_multi_scheduling_blocked()
-		    ? am_blocked
-		    : am_enabled);
+	else
+#endif
+	{
+	    int msb = erts_is_multi_scheduling_blocked();
+	    BIF_RET(!msb
+		    ? am_enabled
+		    : (msb > 0
+		       ? am_blocked
+		       : am_blocked_normal));
 	}
 #endif
     } else if (BIF_ARG_1 == am_build_type) {
@@ -2518,77 +2522,120 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 	res = TUPLE3(hp, make_small(1), make_small(1), make_small(1));
 	BIF_RET(res);
 #else
+	Eterm *hp;
 	Uint total, online, active;
-	switch (erts_schedulers_state(&total,
-				      &online,
-				      &active,
-				      NULL,
-				      NULL,
-				      NULL,
-				      1)) {
-	case ERTS_SCHDLR_SSPND_DONE: {
-	    Eterm *hp = HAlloc(BIF_P, 4);
-	    res = TUPLE3(hp,
-			 make_small(total),
-			 make_small(online),
-			 make_small(active));
-	    BIF_RET(res);
+	erts_schedulers_state(&total, &online, &active,
+			      NULL, NULL, NULL, NULL, NULL);
+	hp = HAlloc(BIF_P, 4);
+	res = TUPLE3(hp,
+		     make_small(total),
+		     make_small(online),
+		     make_small(active));
+	BIF_RET(res);
+#endif
+    } else if (ERTS_IS_ATOM_STR("schedulers_state", BIF_ARG_1)) {
+#ifndef ERTS_SMP
+	Eterm *hp = HAlloc(BIF_P, 4);
+	res = TUPLE3(hp, make_small(1), make_small(1), make_small(1));
+	BIF_RET(res);
+#else
+	Eterm *hp;
+	Uint total, online, active;
+	erts_schedulers_state(&total, &online, &active,
+			      NULL, NULL, NULL, NULL, NULL);
+	hp = HAlloc(BIF_P, 4);
+	res = TUPLE3(hp,
+		     make_small(total),
+		     make_small(online),
+		     make_small(active));
+	BIF_RET(res);
+#endif
+    } else if (ERTS_IS_ATOM_STR("all_schedulers_state", BIF_ARG_1)) {
+#ifndef ERTS_SMP
+	Eterm *hp = HAlloc(BIF_P, 2+5);
+	res = CONS(hp+5,
+		   TUPLE4(hp,
+			  am_normal,
+			  make_small(1),
+			  make_small(1),
+			  make_small(1)),
+		   NIL);
+	BIF_RET(res);
+#else
+	Eterm *hp, tpl;
+	Uint sz, total, online, active,
+	    dirty_cpu_total, dirty_cpu_online, dirty_cpu_active,
+	    dirty_io_total, dirty_io_active;
+	erts_schedulers_state(&total, &online, &active,
+			      &dirty_cpu_total, &dirty_cpu_online, &dirty_cpu_active,
+			      &dirty_io_total, &dirty_io_active);
+
+	sz = 2+5;
+	if (dirty_cpu_total)
+	    sz += 2+5;
+	if (dirty_io_total)
+	    sz += 2+5;
+
+	hp = HAlloc(BIF_P, sz);
+
+	res = NIL;
+	if (dirty_io_total) {
+	    tpl = TUPLE4(hp,
+			 am_dirty_io,
+			 make_small(dirty_io_total),
+			 make_small(dirty_io_total),
+			 make_small(dirty_io_active));
+	    hp += 5;
+	    res = CONS(hp, tpl, res);
+	    hp += 2;
 	}
-	case ERTS_SCHDLR_SSPND_YIELD_RESTART:
-	    ERTS_VBUMP_ALL_REDS(BIF_P);
-	    BIF_TRAP1(bif_export[BIF_system_info_1],
-		      BIF_P, BIF_ARG_1);
-	default:
-	    ASSERT(0);
-	    BIF_ERROR(BIF_P, EXC_INTERNAL_ERROR);
+	if (dirty_cpu_total) {
+	    tpl = TUPLE4(hp,
+			 am_dirty_cpu,
+			 make_small(dirty_cpu_total),
+			 make_small(dirty_cpu_online),
+			 make_small(dirty_cpu_active));
+	    hp += 5;
+	    res = CONS(hp, tpl, res);
+	    hp += 2;
 	}
+	tpl = TUPLE4(hp,
+		     am_normal,
+		     make_small(total),
+		     make_small(online),
+		     make_small(active));
+	hp += 5;
+	res = CONS(hp, tpl, res);
+	BIF_RET(res);
 #endif
     } else if (ERTS_IS_ATOM_STR("schedulers_online", BIF_ARG_1)) {
 #ifndef ERTS_SMP
 	BIF_RET(make_small(1));
 #else
-	Uint total, online, active;
-	switch (erts_schedulers_state(&total, &online, &active, NULL, NULL, NULL, 1)) {
-	case ERTS_SCHDLR_SSPND_DONE:
-	    BIF_RET(make_small(online));
-	case ERTS_SCHDLR_SSPND_YIELD_RESTART:
-	    ERTS_VBUMP_ALL_REDS(BIF_P);
-	    BIF_TRAP1(bif_export[BIF_system_info_1],
-		      BIF_P, BIF_ARG_1);
-	default:
-	    ASSERT(0);
-	    BIF_ERROR(BIF_P, EXC_INTERNAL_ERROR);
-	}
+	Uint online;
+	erts_schedulers_state(NULL, &online, NULL, NULL, NULL, NULL, NULL, NULL);
+	BIF_RET(make_small(online));
 #endif
     } else if (ERTS_IS_ATOM_STR("schedulers_active", BIF_ARG_1)) {
 #ifndef ERTS_SMP
 	BIF_RET(make_small(1));
 #else
-	Uint total, online, active;
-	switch (erts_schedulers_state(&total, &online, &active, NULL, NULL, NULL, 1)) {
-	case ERTS_SCHDLR_SSPND_DONE:
-	    BIF_RET(make_small(active));
-	case ERTS_SCHDLR_SSPND_YIELD_RESTART:
-	    ERTS_VBUMP_ALL_REDS(BIF_P);
-	    BIF_TRAP1(bif_export[BIF_system_info_1],
-		      BIF_P, BIF_ARG_1);
-	default:
-	    ASSERT(0);
-	    BIF_ERROR(BIF_P, EXC_INTERNAL_ERROR);
-	}
+	Uint active;
+	erts_schedulers_state(NULL, NULL, &active, NULL, NULL, NULL, NULL, NULL);
+	BIF_RET(make_small(active));
 #endif
 #if defined(ERTS_SMP) && defined(ERTS_DIRTY_SCHEDULERS)
     } else if (ERTS_IS_ATOM_STR("dirty_cpu_schedulers", BIF_ARG_1)) {
 	Uint dirty_cpu;
-	erts_schedulers_state(NULL, NULL, NULL, &dirty_cpu, NULL, NULL, 1);
+	erts_schedulers_state(NULL, NULL, NULL, &dirty_cpu, NULL, NULL, NULL, NULL);
 	BIF_RET(make_small(dirty_cpu));
     } else if (ERTS_IS_ATOM_STR("dirty_cpu_schedulers_online", BIF_ARG_1)) {
 	Uint dirty_cpu_onln;
-	erts_schedulers_state(NULL, NULL, NULL, NULL, &dirty_cpu_onln, NULL, 1);
+	erts_schedulers_state(NULL, NULL, NULL, NULL, &dirty_cpu_onln, NULL, NULL, NULL);
 	BIF_RET(make_small(dirty_cpu_onln));
     } else if (ERTS_IS_ATOM_STR("dirty_io_schedulers", BIF_ARG_1)) {
 	Uint dirty_io;
-	erts_schedulers_state(NULL, NULL, NULL, NULL, NULL, &dirty_io, 1);
+	erts_schedulers_state(NULL, NULL, NULL, NULL, NULL, NULL, &dirty_io, NULL);
 	BIF_RET(make_small(dirty_io));
 #endif
     } else if (ERTS_IS_ATOM_STR("run_queues", BIF_ARG_1)) {
@@ -2642,7 +2689,16 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 	if (erts_no_schedulers == 1)
 	    BIF_RET(NIL);
 	else
-	    BIF_RET(erts_multi_scheduling_blockers(BIF_P));
+	    BIF_RET(erts_multi_scheduling_blockers(BIF_P, 0));
+#endif
+    } else if (ERTS_IS_ATOM_STR("normal_multi_scheduling_blockers", BIF_ARG_1)) {
+#ifndef ERTS_SMP
+	BIF_RET(NIL);
+#else
+	if (erts_no_schedulers == 1)
+	    BIF_RET(NIL);
+	else
+	    BIF_RET(erts_multi_scheduling_blockers(BIF_P, 1));
 #endif
     } else if (ERTS_IS_ATOM_STR("modified_timing_level", BIF_ARG_1)) {
 	BIF_RET(ERTS_USE_MODIFIED_TIMING()
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index c69cbc023c..41e471a96a 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -153,10 +153,8 @@ 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_WRITE_UNLIKELY(erts_no_dirty_cpu_schedulers);
-Uint ERTS_WRITE_UNLIKELY(erts_no_dirty_io_schedulers);
-#endif
+Uint ERTS_WRITE_UNLIKELY(erts_no_dirty_cpu_schedulers) = 0;
+Uint ERTS_WRITE_UNLIKELY(erts_no_dirty_io_schedulers) = 0;
 
 static char *erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_NO_FLAGS] = {0};
 int erts_aux_work_no_flags = ERTS_SSI_AUX_WORK_NO_FLAGS;
@@ -188,84 +186,176 @@ int erts_disable_proc_not_running_opt;
 
 static ErtsAuxWorkData *aux_thread_aux_work_data;
 
-#define ERTS_SCHDLR_SSPND_CHNG_WAITER		(((erts_aint32_t) 1) << 0)
+#define ERTS_SCHDLR_SSPND_CHNG_NMSB		(((erts_aint32_t) 1) << 0)
 #define ERTS_SCHDLR_SSPND_CHNG_MSB		(((erts_aint32_t) 1) << 1)
 #define ERTS_SCHDLR_SSPND_CHNG_ONLN		(((erts_aint32_t) 1) << 2)
+#define ERTS_SCHDLR_SSPND_CHNG_DCPU_ONLN	(((erts_aint32_t) 1) << 3)
 
-#ifndef DEBUG
+typedef enum {
+    ERTS_SCHED_NORMAL,
+    ERTS_SCHED_DIRTY_CPU,
+    ERTS_SCHED_DIRTY_IO
+} ErtsSchedType;
 
-#define ERTS_SCHDLR_SSPND_CHNG_SET(VAL, OLD_VAL) \
-  erts_smp_atomic32_set_nob(&schdlr_sspnd.changing, (VAL))
+typedef struct {
+    int ongoing;
+    ErtsProcList *blckrs;
+    ErtsProcList *chngq;
+} ErtsMultiSchedulingBlock;
 
-#ifdef ERTS_DIRTY_SCHEDULERS
-#define ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET(VAL, OLD_VAL) \
-  erts_smp_atomic32_set_nob(&schdlr_sspnd.dirty_cpu_changing, (VAL))
-#define ERTS_SCHDLR_SSPND_DIRTY_IO_CHNG_SET(VAL, OLD_VAL) \
-  erts_smp_atomic32_set_nob(&schdlr_sspnd.dirty_io_changing, (VAL))
-#endif
+static struct {
+    erts_smp_mtx_t mtx;
+    Uint32 online;
+    Uint32 curr_online;
+    Uint32 active;
+    erts_smp_atomic32_t changing;
+    ErtsProcList *chngq;
+    Eterm changer;
+    ErtsMultiSchedulingBlock nmsb; /* Normal multi Scheduling Block */
+    ErtsMultiSchedulingBlock msb; /* Multi Scheduling Block */
+} schdlr_sspnd;
 
-#else
+#define ERTS_SCHDLR_SSPND_S_BITS	10
+#define ERTS_SCHDLR_SSPND_DCS_BITS	11
+#define ERTS_SCHDLR_SSPND_DIS_BITS	11
 
-#define ERTS_SCHDLR_SSPND_CHNG_SET(VAL, OLD_VAL)			\
-do {									\
-    erts_aint32_t old_val__;						\
-    old_val__ = erts_smp_atomic32_xchg_nob(&schdlr_sspnd.changing,     	\
-					   (VAL));			\
-    ASSERT(old_val__ == (OLD_VAL));					\
-} while (0)
+#define ERTS_SCHDLR_SSPND_S_MASK	((1 << ERTS_SCHDLR_SSPND_S_BITS)-1)
+#define ERTS_SCHDLR_SSPND_DCS_MASK	((1 << ERTS_SCHDLR_SSPND_DCS_BITS)-1)
+#define ERTS_SCHDLR_SSPND_DIS_MASK	((1 << ERTS_SCHDLR_SSPND_DIS_BITS)-1)
 
-#ifdef ERTS_DIRTY_SCHEDULERS
-#define ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET(VAL, OLD_VAL)		\
-do {									\
-    erts_aint32_t old_val__;						\
-    old_val__ = erts_smp_atomic32_xchg_nob(&schdlr_sspnd.dirty_cpu_changing, \
-					   (VAL));			\
-    ASSERT(old_val__ == (OLD_VAL));					\
-} while (0)
-#define ERTS_SCHDLR_SSPND_DIRTY_IO_CHNG_SET(VAL, OLD_VAL)		\
-do {									\
-    erts_aint32_t old_val__;						\
-    old_val__ = erts_smp_atomic32_xchg_nob(&schdlr_sspnd.dirty_io_changing, \
-					   (VAL));			\
-    ASSERT(old_val__ == (OLD_VAL));					\
-} while (0)
-#endif
+#define ERTS_SCHDLR_SSPND_S_SHIFT	0
+#define ERTS_SCHDLR_SSPND_DCS_SHIFT	(ERTS_SCHDLR_SSPND_S_SHIFT \
+					 + ERTS_SCHDLR_SSPND_S_BITS)
+#define ERTS_SCHDLR_SSPND_DIS_SHIFT	(ERTS_SCHDLR_SSPND_DCS_SHIFT \
+					 + ERTS_SCHDLR_SSPND_DCS_BITS)
 
+#if (ERTS_SCHDLR_SSPND_S_BITS		\
+     + ERTS_SCHDLR_SSPND_DCS_BITS	\
+     + ERTS_SCHDLR_SSPND_DIS_BITS) > 32
+#  error Wont fit in Uint32
 #endif
 
-
-static struct {
-    erts_smp_mtx_t mtx;
-    erts_smp_cnd_t cnd;
-    int online;
-    int curr_online;
-    int wait_curr_online;
-#ifdef ERTS_DIRTY_SCHEDULERS
-    int dirty_cpu_online;
-    int dirty_cpu_curr_online;
-    int dirty_cpu_wait_curr_online;
-    int dirty_io_online;
-    int dirty_io_curr_online;
-    int dirty_io_wait_curr_online;
+#if (ERTS_MAX_NO_OF_SCHEDULERS-1) > ERTS_SCHDLR_SSPND_S_MASK
+#  error Max no schedulers wont fit in its bit-field
 #endif
-    erts_smp_atomic32_t changing;
-    erts_smp_atomic32_t active;
-#ifdef ERTS_DIRTY_SCHEDULERS
-    erts_smp_atomic32_t dirty_cpu_changing;
-    erts_smp_atomic32_t dirty_cpu_active;
-    erts_smp_atomic32_t dirty_io_changing;
-    erts_smp_atomic32_t dirty_io_active;
+#if ERTS_MAX_NO_OF_DIRTY_CPU_SCHEDULERS > ERTS_SCHDLR_SSPND_DCS_MASK
+#  error Max no dirty cpu schedulers wont fit in its bit-field
 #endif
-    struct {
-	int ongoing;
-	long wait_active;
-#ifdef ERTS_DIRTY_SCHEDULERS
-	long dirty_cpu_wait_active;
-	long dirty_io_wait_active;
+#if ERTS_MAX_NO_OF_DIRTY_IO_SCHEDULERS > ERTS_SCHDLR_SSPND_DIS_MASK
+#  error Max no dirty io schedulers wont fit in its bit-field
 #endif
-	ErtsProcList *procs;
-    } msb; /* Multi Scheduling Block */
-} schdlr_sspnd;
+
+#define ERTS_SCHDLR_SSPND_MAKE_NSCHEDS_VAL(S, DCS, DIS)			\
+    ((((Uint32) (((S) & ERTS_SCHDLR_SSPND_S_MASK))-1)			\
+      << ERTS_SCHDLR_SSPND_S_SHIFT)					\
+     | ((((Uint32) ((DCS) & ERTS_SCHDLR_SSPND_DCS_MASK))		\
+	 << ERTS_SCHDLR_SSPND_DCS_SHIFT))				\
+     | ((((Uint32) ((DIS) & ERTS_SCHDLR_SSPND_DIS_MASK))		\
+	 << ERTS_SCHDLR_SSPND_DIS_SHIFT)))
+
+static void init_scheduler_suspend(void);
+
+static ERTS_INLINE Uint32
+schdlr_sspnd_get_nscheds(Uint32 *valp, ErtsSchedType type)
+{
+    Uint32 res = (Uint32) (*valp);
+    switch (type) {
+    case ERTS_SCHED_NORMAL:
+	res >>= ERTS_SCHDLR_SSPND_S_SHIFT;
+	res &= (Uint32) ERTS_SCHDLR_SSPND_S_MASK;
+	res++;
+	break;
+    case ERTS_SCHED_DIRTY_CPU:
+	res >>= ERTS_SCHDLR_SSPND_DCS_SHIFT;
+	res &= (Uint32) ERTS_SCHDLR_SSPND_DCS_MASK;
+	break;
+    case ERTS_SCHED_DIRTY_IO:
+	res >>= ERTS_SCHDLR_SSPND_DIS_SHIFT;
+	res &= (Uint32) ERTS_SCHDLR_SSPND_DIS_MASK;
+	break;
+    default:
+	ERTS_INTERNAL_ERROR("Invalid scheduler type");
+	return 0;
+    }
+
+    return res;
+}
+
+static ERTS_INLINE void
+schdlr_sspnd_dec_nscheds(Uint32 *valp, ErtsSchedType type)
+{
+    ASSERT(schdlr_sspnd_get_nscheds(valp, type) > 0);
+
+    switch (type) {
+    case ERTS_SCHED_NORMAL:
+	*valp -= ((Uint32) 1) << ERTS_SCHDLR_SSPND_S_SHIFT;
+	break;
+    case ERTS_SCHED_DIRTY_CPU:
+	*valp -= ((Uint32) 1) << ERTS_SCHDLR_SSPND_DCS_SHIFT;
+	break;
+    case ERTS_SCHED_DIRTY_IO:
+	*valp -= ((Uint32) 1) << ERTS_SCHDLR_SSPND_DIS_SHIFT;
+	break;
+    default:
+	ERTS_INTERNAL_ERROR("Invalid scheduler type");
+    }
+}
+
+static ERTS_INLINE void
+schdlr_sspnd_inc_nscheds(Uint32 *valp, ErtsSchedType type)
+{
+    switch (type) {
+    case ERTS_SCHED_NORMAL:
+	ASSERT(schdlr_sspnd_get_nscheds(valp, type)
+	       < ERTS_MAX_NO_OF_SCHEDULERS-1);
+	*valp += ((Uint32) 1) << ERTS_SCHDLR_SSPND_S_SHIFT;
+	break;
+    case ERTS_SCHED_DIRTY_CPU:
+	ASSERT(schdlr_sspnd_get_nscheds(valp, type)
+	       < ERTS_MAX_NO_OF_DIRTY_CPU_SCHEDULERS);
+	*valp += ((Uint32) 1) << ERTS_SCHDLR_SSPND_DCS_SHIFT;
+	break;
+    case ERTS_SCHED_DIRTY_IO:
+	ASSERT(schdlr_sspnd_get_nscheds(valp, type)
+	       < ERTS_MAX_NO_OF_DIRTY_IO_SCHEDULERS);
+	*valp += ((Uint32) 1) << ERTS_SCHDLR_SSPND_DIS_SHIFT;
+	break;
+    default:
+	ERTS_INTERNAL_ERROR("Invalid scheduler type");
+    }
+}
+
+static ERTS_INLINE void
+schdlr_sspnd_set_nscheds(Uint32 *valp, ErtsSchedType type, Uint32 no)
+{
+    Uint32 val = *valp;
+
+    switch (type) {
+    case ERTS_SCHED_NORMAL:
+	ASSERT(no > 0);
+	val &= ~(((Uint32) ERTS_SCHDLR_SSPND_S_MASK)
+		 << ERTS_SCHDLR_SSPND_S_SHIFT);
+	val |= (((no-1) & ((Uint32) ERTS_SCHDLR_SSPND_S_MASK))
+		<< ERTS_SCHDLR_SSPND_S_SHIFT);
+	break;
+    case ERTS_SCHED_DIRTY_CPU:
+	val &= ~(((Uint32) ERTS_SCHDLR_SSPND_DCS_MASK)
+		 << ERTS_SCHDLR_SSPND_DCS_SHIFT);
+	val |= ((no & ((Uint32) ERTS_SCHDLR_SSPND_DCS_MASK))
+		 << ERTS_SCHDLR_SSPND_DCS_SHIFT);
+	break;
+    case ERTS_SCHED_DIRTY_IO:
+	val &= ~(((Uint32) ERTS_SCHDLR_SSPND_DIS_MASK)
+		 << ERTS_SCHDLR_SSPND_DIS_SHIFT);
+	val |= ((no & ((Uint32) ERTS_SCHDLR_SSPND_DIS_MASK))
+		<< ERTS_SCHDLR_SSPND_DIS_SHIFT);
+	break;
+    default:
+	ERTS_INTERNAL_ERROR("Invalid scheduler type");
+    }
+
+    *valp = val;
+}
 
 static struct {
     erts_smp_mtx_t update_mtx;
@@ -426,8 +516,10 @@ do {									\
 do {									\
     ErtsRunQueue *RQVAR;						\
     int ix__;								\
+    int online__ = (int) schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,	\
+						  ERTS_SCHED_NORMAL);	\
     ERTS_SMP_LC_ASSERT(erts_smp_lc_mtx_is_locked(&schdlr_sspnd.mtx));	\
-    for (ix__ = 0; ix__ < schdlr_sspnd.online; ix__++) {		\
+    for (ix__ = 0; ix__ < online__; ix__++) {				\
 	RQVAR = ERTS_RUNQ_IX(ix__);					\
 	erts_smp_runq_lock(RQVAR);					\
 	{ DO; }								\
@@ -1188,6 +1280,15 @@ proclist_create(Process *p)
     return plp;
 }
 
+static ERTS_INLINE ErtsProcList *
+proclist_copy(ErtsProcList *plp0)
+{
+    ErtsProcList *plp1 = proclist_alloc();
+    plp1->pid = plp0->pid;
+    plp1->started_interval = plp0->started_interval;
+    return plp1;
+}
+
 static ERTS_INLINE void
 proclist_destroy(ErtsProcList *plp)
 {
@@ -1195,6 +1296,12 @@ proclist_destroy(ErtsProcList *plp)
 }
 
 ErtsProcList *
+erts_proclist_copy(ErtsProcList *plp)
+{
+    return proclist_copy(plp);
+}
+
+ErtsProcList *
 erts_proclist_create(Process *p)
 {
     return proclist_create(p);
@@ -2632,13 +2739,6 @@ sched_active(Uint no, ErtsRunQueue *rq)
 	profile_scheduler(make_small(no), am_active);
 }
 
-static int ERTS_INLINE
-ongoing_multi_scheduling_block(void)
-{
-    ERTS_SMP_LC_ASSERT(erts_lc_mtx_is_locked(&schdlr_sspnd.mtx));
-    return schdlr_sspnd.msb.ongoing;
-}
-
 static ERTS_INLINE void
 empty_runq_aux(ErtsRunQueue *rq, Uint32 old_flags)
 {
@@ -3025,8 +3125,10 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 		    timeout_time = erts_check_next_timeout_time(esdp);
 		    current_time = erts_get_monotonic_time(esdp);
 		    do_timeout = (current_time >= timeout_time);
-		} else
+		} else {
+		    current_time = 0;
 		    timeout_time = ERTS_MONOTONIC_TIME_MAX;
+		}
 		if (do_timeout) {
 		    if (!thr_prgr_active) {
 			erts_thr_progress_active(esdp, thr_prgr_active = 1);
@@ -3836,24 +3938,33 @@ static ERTS_INLINE void
 resume_run_queue(ErtsRunQueue *rq)
 {
     int pix;
+    Uint32 oflgs;
 
     erts_smp_runq_lock(rq);
 
-    (void) ERTS_RUNQ_FLGS_READ_BSET(rq,
-				    (ERTS_RUNQ_FLG_OUT_OF_WORK
-				     | ERTS_RUNQ_FLG_HALFTIME_OUT_OF_WORK
-				     | ERTS_RUNQ_FLG_SUSPENDED),
-				    (ERTS_RUNQ_FLG_OUT_OF_WORK
-				     | ERTS_RUNQ_FLG_HALFTIME_OUT_OF_WORK));
+    oflgs = ERTS_RUNQ_FLGS_READ_BSET(rq,
+				     (ERTS_RUNQ_FLG_OUT_OF_WORK
+				      | ERTS_RUNQ_FLG_HALFTIME_OUT_OF_WORK
+				      | ERTS_RUNQ_FLG_SUSPENDED),
+				     (ERTS_RUNQ_FLG_OUT_OF_WORK
+				      | ERTS_RUNQ_FLG_HALFTIME_OUT_OF_WORK));
+
+    if (oflgs & ERTS_RUNQ_FLG_SUSPENDED) {
+	erts_aint32_t len;
+
+	rq->check_balance_reds = ERTS_RUNQ_CALL_CHECK_BALANCE_REDS;
+	for (pix = 0; pix < ERTS_NO_PROC_PRIO_LEVELS; pix++) {
+	    len = erts_smp_atomic32_read_dirty(&rq->procs.prio_info[pix].len);
+	    rq->procs.prio_info[pix].max_len = len;
+	    rq->procs.prio_info[pix].reds = 0;
+	}
+	len = erts_smp_atomic32_read_dirty(&rq->ports.info.len);
+	rq->ports.info.max_len = len;
+	rq->ports.info.reds = 0;
+	len = erts_smp_atomic32_read_dirty(&rq->len);
+	rq->max_len = len;
 
-    rq->check_balance_reds = ERTS_RUNQ_CALL_CHECK_BALANCE_REDS;
-    for (pix = 0; pix < ERTS_NO_PROC_PRIO_LEVELS; pix++) {
-	rq->procs.prio_info[pix].max_len = 0;
-	rq->procs.prio_info[pix].reds = 0;
     }
-    rq->ports.info.max_len = 0;
-    rq->ports.info.reds = 0;
-    rq->max_len = 0;
 
     erts_smp_runq_unlock(rq);
 
@@ -5632,6 +5743,9 @@ erts_init_scheduling(int no_schedulers, int no_schedulers_online
     char *daww_ptr;
     size_t daww_sz;
     size_t size_runqs;
+#ifdef ERTS_SMP
+    erts_aint32_t set_schdlr_sspnd_change_flags;
+#endif
 
     init_misc_op_list_alloc();
     init_proc_sys_task_queues_alloc();
@@ -5869,25 +5983,6 @@ erts_init_scheduling(int no_schedulers, int no_schedulers_online
 	erts_alloc_permanent_cache_aligned(ERTS_ALC_T_SCHDLR_DATA,
 					   sizeof(ErtsAuxWorkData));
 
-    erts_smp_mtx_init(&schdlr_sspnd.mtx, "schdlr_sspnd");
-    erts_smp_cnd_init(&schdlr_sspnd.cnd);
-
-    erts_smp_atomic32_init_nob(&schdlr_sspnd.changing, 0);
-    schdlr_sspnd.online = no_schedulers_online;
-    schdlr_sspnd.curr_online = no_schedulers;
-    schdlr_sspnd.msb.ongoing = 0;
-    erts_smp_atomic32_init_nob(&schdlr_sspnd.active, no_schedulers);
-#ifdef ERTS_DIRTY_SCHEDULERS
-    erts_smp_atomic32_init_nob(&schdlr_sspnd.dirty_cpu_changing, 0);
-    schdlr_sspnd.dirty_cpu_online = no_dirty_cpu_schedulers_online;
-    schdlr_sspnd.dirty_cpu_curr_online = no_dirty_cpu_schedulers;
-    erts_smp_atomic32_init_nob(&schdlr_sspnd.dirty_cpu_active, no_dirty_cpu_schedulers);
-    erts_smp_atomic32_init_nob(&schdlr_sspnd.dirty_io_changing, 0);
-    schdlr_sspnd.dirty_io_online = no_dirty_io_schedulers;
-    schdlr_sspnd.dirty_io_curr_online = no_dirty_io_schedulers;
-    erts_smp_atomic32_init_nob(&schdlr_sspnd.dirty_io_active, no_dirty_io_schedulers);
-#endif
-    schdlr_sspnd.msb.procs = NULL;
     init_no_runqs(no_schedulers_online, no_schedulers_online);
     balance_info.last_active_runqs = no_schedulers;
     erts_smp_mtx_init(&balance_info.update_mtx, "migration_info_update");
@@ -5902,32 +5997,66 @@ erts_init_scheduling(int no_schedulers, int no_schedulers_online
 
     init_migration_paths();
 
-    if (no_schedulers_online < no_schedulers) {
+    init_scheduler_suspend();
+
+    set_schdlr_sspnd_change_flags = 0;
+
+    schdlr_sspnd_set_nscheds(&schdlr_sspnd.online,
+			     ERTS_SCHED_NORMAL,
+			     no_schedulers_online);
+    schdlr_sspnd_set_nscheds(&schdlr_sspnd.curr_online,
+			     ERTS_SCHED_NORMAL,
+			     no_schedulers);
+    schdlr_sspnd_set_nscheds(&schdlr_sspnd.active,
+			     ERTS_SCHED_NORMAL,
+			     no_schedulers);
+
+    if (no_schedulers_online != no_schedulers) {
+	ASSERT(no_schedulers_online < no_schedulers);
+	set_schdlr_sspnd_change_flags |= ERTS_SCHDLR_SSPND_CHNG_ONLN;
+	schdlr_sspnd.changer = am_init;
 	change_no_used_runqs(no_schedulers_online);
 	for (ix = no_schedulers_online; ix < erts_no_run_queues; ix++)
 	    suspend_run_queue(ERTS_RUNQ_IX(ix));
     }
 
-    schdlr_sspnd.wait_curr_online = no_schedulers_online;
-    schdlr_sspnd.curr_online *= 2; /* Boot strapping... */
-    ERTS_SCHDLR_SSPND_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_ONLN
-				| ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
 #ifdef ERTS_DIRTY_SCHEDULERS
-    schdlr_sspnd.dirty_cpu_wait_curr_online = no_dirty_cpu_schedulers_online;
-    schdlr_sspnd.dirty_cpu_curr_online *= 2;
-    ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_ONLN
-					  | ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
-    for (ix = no_dirty_cpu_schedulers_online; ix < no_dirty_cpu_schedulers; ix++) {
-	ErtsSchedulerData* esdp = ERTS_DIRTY_CPU_SCHEDULER_IX(ix);
-	erts_smp_atomic32_read_bor_nob(&esdp->ssi->flags, ERTS_SSI_FLG_SUSPENDED);
+
+    schdlr_sspnd_set_nscheds(&schdlr_sspnd.online,
+			     ERTS_SCHED_DIRTY_CPU,
+			     no_dirty_cpu_schedulers_online);
+    schdlr_sspnd_set_nscheds(&schdlr_sspnd.curr_online,
+			     ERTS_SCHED_DIRTY_CPU,
+			     no_dirty_cpu_schedulers);
+    schdlr_sspnd_set_nscheds(&schdlr_sspnd.active,
+			     ERTS_SCHED_DIRTY_CPU,
+			     no_dirty_cpu_schedulers);
+
+    if (no_dirty_cpu_schedulers_online != no_dirty_cpu_schedulers) {
+	ASSERT(no_dirty_cpu_schedulers_online < no_dirty_cpu_schedulers);
+	set_schdlr_sspnd_change_flags |= ERTS_SCHDLR_SSPND_CHNG_DCPU_ONLN;
+	for (ix = no_dirty_cpu_schedulers_online; ix < no_dirty_cpu_schedulers; ix++) {
+	    ErtsSchedulerData* esdp = ERTS_DIRTY_CPU_SCHEDULER_IX(ix);
+	    erts_smp_atomic32_read_bor_nob(&esdp->ssi->flags, ERTS_SSI_FLG_SUSPENDED);
+	}
     }
 
-    schdlr_sspnd.dirty_io_wait_curr_online = no_dirty_io_schedulers;
-    schdlr_sspnd.dirty_io_curr_online *= 2;
-    ERTS_SCHDLR_SSPND_DIRTY_IO_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_ONLN
-					 | ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
+    schdlr_sspnd_set_nscheds(&schdlr_sspnd.online,
+			     ERTS_SCHED_DIRTY_IO,
+			     no_dirty_io_schedulers);
+    schdlr_sspnd_set_nscheds(&schdlr_sspnd.curr_online,
+			     ERTS_SCHED_DIRTY_IO,
+			     no_dirty_io_schedulers);
+    schdlr_sspnd_set_nscheds(&schdlr_sspnd.active,
+			     ERTS_SCHED_DIRTY_IO,
+			     no_dirty_io_schedulers);
+
 #endif
 
+    if (set_schdlr_sspnd_change_flags)
+	erts_smp_atomic32_set_nob(&schdlr_sspnd.changing,
+				  set_schdlr_sspnd_change_flags);
+
     erts_smp_atomic32_init_nob(&doing_sys_schedule, 0);
 
     init_misc_aux_work();
@@ -5942,11 +6071,9 @@ erts_init_scheduling(int no_schedulers, int no_schedulers_online
 #endif
     }
     erts_no_schedulers = 1;
-#ifdef ERTS_DIRTY_SCHEDULERS
     erts_no_dirty_cpu_schedulers = 0;
     erts_no_dirty_io_schedulers = 0;
 #endif
-#endif
 
     erts_smp_atomic32_init_nob(&function_calls, 0);
 
@@ -6705,19 +6832,6 @@ resume_process(Process *p, ErtsProcLocks locks)
     add2runq(enqueue, enq_prio, p, state, NULL);
 }
 
-int
-erts_get_max_no_executing_schedulers(void)
-{
-#ifdef ERTS_SMP
-    if (erts_smp_atomic32_read_nob(&schdlr_sspnd.changing))
-	return (int) erts_no_schedulers;
-    ERTS_THR_MEMORY_BARRIER;
-    return (int) erts_smp_atomic32_read_nob(&schdlr_sspnd.active);
-#else
-    return 1;
-#endif
-}
-
 #ifdef ERTS_SMP
 
 static void
@@ -6820,42 +6934,82 @@ sched_set_suspended_sleeptype(ErtsSchedulerSleepInfo *ssi)
     }
 }
 
-#ifdef ERTS_DIRTY_SCHEDULERS
+static void
+init_scheduler_suspend(void)
+{
+    erts_smp_mtx_init(&schdlr_sspnd.mtx, "schdlr_sspnd");
+    schdlr_sspnd.online = ERTS_SCHDLR_SSPND_MAKE_NSCHEDS_VAL(1, 0, 0);
+    schdlr_sspnd.curr_online = ERTS_SCHDLR_SSPND_MAKE_NSCHEDS_VAL(1, 0, 0);
+    schdlr_sspnd.active = ERTS_SCHDLR_SSPND_MAKE_NSCHEDS_VAL(1, 0, 0);
+    erts_smp_atomic32_init_nob(&schdlr_sspnd.changing, 0);
+    schdlr_sspnd.chngq = NULL;
+    schdlr_sspnd.changer = am_false;
+    schdlr_sspnd.nmsb.ongoing = 0;
+    schdlr_sspnd.nmsb.blckrs = NULL;
+    schdlr_sspnd.nmsb.chngq = NULL;
+    schdlr_sspnd.msb.ongoing = 0;
+    schdlr_sspnd.msb.blckrs = NULL;
+    schdlr_sspnd.msb.chngq = NULL;
+}
+
+typedef struct {
+    struct {
+	Eterm chngr;
+	Eterm nxt;
+    } onln;
+    struct {
+	ErtsProcList *chngrs;
+    } msb;
+} ErtsSchdlrSspndResume;
+
+static void
+schdlr_sspnd_resume_proc(Eterm pid)
+{
+    Process *p = erts_pid2proc(NULL, 0, pid, ERTS_PROC_LOCK_STATUS);
+    if (p) {
+	resume_process(p, ERTS_PROC_LOCK_STATUS);
+	erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
+    }
+}
+
+static ERTS_INLINE void
+schdlr_sspnd_resume_procs(ErtsSchedType sched_type,
+			  ErtsSchdlrSspndResume *resume)
+{
+    if (is_internal_pid(resume->onln.chngr)) {
+	schdlr_sspnd_resume_proc(resume->onln.chngr);
+	resume->onln.chngr = NIL;
+    }
+    if (is_internal_pid(resume->onln.nxt)) {
+	schdlr_sspnd_resume_proc(resume->onln.nxt);
+	resume->onln.nxt = NIL;
+    }
+    while (resume->msb.chngrs) {
+	ErtsProcList *plp = resume->msb.chngrs;
+	resume->msb.chngrs = plp->next;
+	schdlr_sspnd_resume_proc(plp->pid);
+	proclist_destroy(plp);
+    }
+}
 
 static void
 suspend_scheduler(ErtsSchedulerData *esdp)
 {
     erts_aint32_t flgs;
     erts_aint32_t changing;
-#ifdef ERTS_DIRTY_SCHEDULERS
-    long no = (long) (ERTS_SCHEDULER_IS_DIRTY(esdp)
-		      ? ERTS_DIRTY_SCHEDULER_NO(esdp)
-		      : esdp->no);
-#else
-    long no = (long) esdp->no;
-#endif
+    long no;
     ErtsSchedulerSleepInfo *ssi = esdp->ssi;
-    long active_schedulers;
     int curr_online = 1;
-    int wake = 0;
+    ErtsSchdlrSspndResume resume = {{NIL, NIL}, {NULL}};
     erts_aint32_t aux_work;
     int thr_prgr_active = 1;
     ErtsStuckBoundProcesses sbp = {NULL, NULL};
-    int* ss_onlinep;
-    int* ss_curr_onlinep;
-    int* ss_wait_curr_onlinep;
-    long* ss_wait_activep;
-    long ss_wait_active_target;
-    erts_smp_atomic32_t* ss_changingp;
-    erts_smp_atomic32_t* ss_activep;
+    ErtsSchedType sched_type;
+    erts_aint32_t online_flag;
 
     /*
      * Schedulers may be suspended in two different ways:
      * - A scheduler may be suspended since it is not online.
-     *   All schedulers with scheduler ids greater than
-     *   schdlr_sspnd.online are suspended; same for dirty
-     *   schedulers and schdlr_sspnd.dirty_cpu_online and
-     *   schdlr_sspnd.dirty_io_online.
      * - Multi scheduling is blocked. All schedulers except the
      *   scheduler with scheduler id 1 are suspended, and all
      *   dirty CPU and dirty I/O schedulers are suspended.
@@ -6863,27 +7017,43 @@ suspend_scheduler(ErtsSchedulerData *esdp)
      * Regardless of why a scheduler is suspended, it ends up here.
      */
 
-    ASSERT(ERTS_SCHEDULER_IS_DIRTY(esdp) || no != 1);
-
 #ifdef ERTS_DIRTY_SCHEDULERS
     if (ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+	no = ERTS_DIRTY_SCHEDULER_NO(esdp);
+	if (ERTS_RUNQ_IS_DIRTY_CPU_RUNQ(esdp->run_queue)) {
+	    online_flag = ERTS_SCHDLR_SSPND_CHNG_DCPU_ONLN;
+	    sched_type = ERTS_SCHED_DIRTY_CPU;
+	}
+	else {
+	    online_flag = 0;
+	    sched_type = ERTS_SCHED_DIRTY_IO;
+	}
+    }
+    else
+#endif
+    {
+	online_flag = ERTS_SCHDLR_SSPND_CHNG_ONLN;
+	no = esdp->no;
+	sched_type = ERTS_SCHED_NORMAL;
+    }
+
+    ASSERT(sched_type != ERTS_SCHED_NORMAL || no != 1);
+
+    if (sched_type != ERTS_SCHED_NORMAL) {
 	if (erts_smp_mtx_trylock(&schdlr_sspnd.mtx) == EBUSY) {
 	    erts_smp_runq_unlock(esdp->run_queue);
 	    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
 	    erts_smp_runq_lock(esdp->run_queue);
 	}
-	if (ongoing_multi_scheduling_block())
+	if (schdlr_sspnd.msb.ongoing)
 	    evacuate_run_queue(esdp->run_queue, &sbp);
-    } else
-#endif
+	erts_smp_runq_unlock(esdp->run_queue);
+    }
+    else {
 	evacuate_run_queue(esdp->run_queue, &sbp);
 
-    erts_smp_runq_unlock(esdp->run_queue);
+	erts_smp_runq_unlock(esdp->run_queue);
 
-#ifdef ERTS_DIRTY_SCHEDULERS
-    if (!ERTS_SCHEDULER_IS_DIRTY(esdp))
-#endif
-    {
 	erts_sched_check_cpu_bind_prep_suspend(esdp);
 
 	if (erts_system_profile_flags.scheduler)
@@ -6897,318 +7067,115 @@ suspend_scheduler(ErtsSchedulerData *esdp)
     flgs = sched_prep_spin_suspended(ssi, ERTS_SSI_FLG_SUSPENDED);
     if (flgs & ERTS_SSI_FLG_SUSPENDED) {
 
-#ifdef ERTS_DIRTY_SCHEDULERS
-	if (ERTS_SCHEDULER_IS_DIRTY(esdp)) {
-	    if (ERTS_RUNQ_IS_DIRTY_CPU_RUNQ(esdp->run_queue)) {
-		active_schedulers = erts_smp_atomic32_dec_read_nob(&schdlr_sspnd.dirty_cpu_active);
-		ASSERT(active_schedulers >= 0);
-		changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_cpu_changing);
-		ss_onlinep = &schdlr_sspnd.dirty_cpu_online;
-		ss_curr_onlinep = &schdlr_sspnd.dirty_cpu_curr_online;
-		ss_wait_curr_onlinep = &schdlr_sspnd.dirty_cpu_wait_curr_online;
-		ss_changingp = &schdlr_sspnd.dirty_cpu_changing;
-		ss_wait_activep = &schdlr_sspnd.msb.dirty_cpu_wait_active;
-		ss_activep = &schdlr_sspnd.dirty_cpu_active;
-	    } else {
-		active_schedulers = erts_smp_atomic32_dec_read_nob(&schdlr_sspnd.dirty_io_active);
-		ASSERT(active_schedulers >= 0);
-		changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_io_changing);
-		ss_onlinep = &schdlr_sspnd.dirty_io_online;
-		ss_curr_onlinep = &schdlr_sspnd.dirty_io_curr_online;
-		ss_wait_curr_onlinep = &schdlr_sspnd.dirty_io_wait_curr_online;
-		ss_changingp = &schdlr_sspnd.dirty_io_changing;
-		ss_wait_activep = &schdlr_sspnd.msb.dirty_io_wait_active;
-		ss_activep = &schdlr_sspnd.dirty_io_active;
-	    }
-	    ss_wait_active_target = 0;
-	}
-	else
-#endif
-	{
-	    active_schedulers = erts_smp_atomic32_dec_read_nob(&schdlr_sspnd.active);
-	    ASSERT(active_schedulers >= 1);
-	    changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
-	    ss_onlinep = &schdlr_sspnd.online;
-	    ss_curr_onlinep = &schdlr_sspnd.curr_online;
-	    ss_wait_curr_onlinep = &schdlr_sspnd.wait_curr_online;
-	    ss_changingp = &schdlr_sspnd.changing;
-	    ss_wait_activep = &schdlr_sspnd.msb.wait_active;
-	    ss_activep = &schdlr_sspnd.active;
-	    ss_wait_active_target = 1;
-	}
-	if (changing & ERTS_SCHDLR_SSPND_CHNG_MSB) {
-	    if (active_schedulers == *ss_wait_activep)
-		wake = 1;
-	    if (active_schedulers == ss_wait_active_target) {
-		changing = erts_smp_atomic32_read_band_nob(ss_changingp,
-							   ~ERTS_SCHDLR_SSPND_CHNG_MSB);
-		changing &= ~ERTS_SCHDLR_SSPND_CHNG_MSB;
-	    }
-	}
+	schdlr_sspnd_dec_nscheds(&schdlr_sspnd.active, sched_type);
 
-	while (1) {
-	    if (changing & ERTS_SCHDLR_SSPND_CHNG_ONLN) {
-		int changed = 0;
-		if (no > *ss_onlinep && curr_online) {
-		    (*ss_curr_onlinep)--;
-		    curr_online = 0;
-		    changed = 1;
-		}
-		else if (no <= *ss_onlinep && !curr_online) {
-		    (*ss_curr_onlinep)++;
-		    curr_online = 1;
-		    changed = 1;
-		}
-		if (changed
-		    && *ss_curr_onlinep == *ss_wait_curr_onlinep)
-		    wake = 1;
-		if (*ss_onlinep == *ss_curr_onlinep) {
-		    changing = erts_smp_atomic32_read_band_nob(ss_changingp,
-							       ~ERTS_SCHDLR_SSPND_CHNG_ONLN);
-		    changing &= ~ERTS_SCHDLR_SSPND_CHNG_ONLN;
-		}
-	    }
-
-	    if (wake) {
-		erts_smp_cnd_signal(&schdlr_sspnd.cnd);
-		wake = 0;
-	    }
+	ASSERT(schdlr_sspnd_get_nscheds(&schdlr_sspnd.active,
+					ERTS_SCHED_NORMAL) >= 1);
 
-	    if (curr_online && !ongoing_multi_scheduling_block()) {
-		flgs = erts_smp_atomic32_read_acqb(&ssi->flags);
-		if (!(flgs & ERTS_SSI_FLG_SUSPENDED))
-		    break;
-	    }
-	    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-
-	    while (1) {
-		erts_aint32_t qmask;
-		erts_aint32_t flgs;
+	changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
 
-		qmask = (ERTS_RUNQ_FLGS_GET(esdp->run_queue)
-			 & ERTS_RUNQ_FLGS_QMASK);
-		aux_work = erts_atomic32_read_acqb(&ssi->aux_work);
-		if (aux_work|qmask) {
-		    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);
+	while (1) {
 
-			if (aux_work && erts_thr_progress_update(esdp))
-			    erts_thr_progress_leader_update(esdp);
+	    if (changing & (ERTS_SCHDLR_SSPND_CHNG_NMSB
+			    | ERTS_SCHDLR_SSPND_CHNG_MSB)) {
+		int i = 0;
+		ErtsMultiSchedulingBlock *msb[3] = {0};
+		if (changing & ERTS_SCHDLR_SSPND_CHNG_NMSB)
+		    msb[i++] = &schdlr_sspnd.nmsb;
+		if (changing & ERTS_SCHDLR_SSPND_CHNG_MSB)
+		    msb[i++] = &schdlr_sspnd.msb;
+
+		for (i = 0; msb[i]; i++) {
+		    erts_aint32_t clr_flg = 0;
+
+		    if (msb[i] == &schdlr_sspnd.nmsb
+			&& schdlr_sspnd_get_nscheds(&schdlr_sspnd.active,
+						    ERTS_SCHED_NORMAL) == 1) {
+			clr_flg = ERTS_SCHDLR_SSPND_CHNG_NMSB;
 		    }
-		    if (qmask) {
-#ifdef ERTS_DIRTY_SCHEDULERS
-			if (ERTS_SCHEDULER_IS_DIRTY(esdp)) {
-			    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-			    erts_smp_runq_lock(esdp->run_queue);
-			    if (ongoing_multi_scheduling_block())
-				evacuate_run_queue(esdp->run_queue, &sbp);
-			    erts_smp_runq_unlock(esdp->run_queue);
-			    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-			} else
-#endif
-			{
-			    erts_smp_runq_lock(esdp->run_queue);
-			    evacuate_run_queue(esdp->run_queue, &sbp);
-			    erts_smp_runq_unlock(esdp->run_queue);
-			}
-		    }
-		}
-
-		if (!aux_work) {
-#ifdef ERTS_DIRTY_SCHEDULERS
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp))
-#endif
-		    {
-			if (thr_prgr_active) {
-			    erts_thr_progress_active(esdp, thr_prgr_active = 0);
-			    sched_wall_time_change(esdp, 0);
-			}
-			erts_thr_progress_prepare_wait(esdp);
+		    else if (schdlr_sspnd.active
+			     == ERTS_SCHDLR_SSPND_MAKE_NSCHEDS_VAL(1, 0, 0)) {
+			clr_flg = ERTS_SCHDLR_SSPND_CHNG_MSB;
 		    }
-		    flgs = sched_spin_suspended(ssi,
-						ERTS_SCHED_SUSPEND_SLEEP_SPINCOUNT);
-		    if (flgs == (ERTS_SSI_FLG_SLEEPING
-				 | ERTS_SSI_FLG_WAITING
-				 | ERTS_SSI_FLG_SUSPENDED)) {
-			flgs = sched_set_suspended_sleeptype(ssi);
-			if (flgs == (ERTS_SSI_FLG_SLEEPING
-				     | ERTS_SSI_FLG_TSE_SLEEPING
-				     | ERTS_SSI_FLG_WAITING
-				     | ERTS_SSI_FLG_SUSPENDED)) {
-			    int res;
 
-			    do {
-				res = erts_tse_twait(ssi->event, -1);
-			    } while (res == EINTR);
+		    if (clr_flg) {
+			ErtsProcList *plp, *end_plp;
+			changing = erts_smp_atomic32_read_band_nob(&schdlr_sspnd.changing,
+								   ~clr_flg);
+			changing &= ~clr_flg;
+			(void) erts_proclist_fetch(&msb[i]->chngq, &end_plp);
+			/* resume processes that initiated the multi scheduling block... */
+			plp = msb[i]->chngq;
+			while (plp) {
+			    erts_proclist_store_last(&msb[i]->blckrs,
+						     proclist_copy(plp));
+			    plp = plp->next;
 			}
+			if (end_plp)
+			    end_plp->next = resume.msb.chngrs;
+			resume.msb.chngrs = msb[i]->chngq;
+			msb[i]->chngq = NULL;
 		    }
-#ifdef ERTS_DIRTY_SCHEDULERS
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp))
-#endif
-			erts_thr_progress_finalize_wait(esdp);
 		}
-
-		flgs = sched_prep_spin_suspended(ssi, (ERTS_SSI_FLG_WAITING
-						       | ERTS_SSI_FLG_SUSPENDED));
-		if (!(flgs & ERTS_SSI_FLG_SUSPENDED))
-		    break;
-		changing = erts_smp_atomic32_read_nob(ss_changingp);
-		if (changing & ~ERTS_SCHDLR_SSPND_CHNG_WAITER)
-		    break;
-	    }
-
-	    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-	    changing = erts_smp_atomic32_read_nob(ss_changingp);
-	}
-
-	active_schedulers = erts_smp_atomic32_inc_read_nob(ss_activep);
-	changing = erts_smp_atomic32_read_nob(ss_changingp);
-	if ((changing & ERTS_SCHDLR_SSPND_CHNG_MSB)
-	    && *ss_onlinep == active_schedulers) {
-	    erts_smp_atomic32_read_band_nob(ss_changingp,
-					    ~ERTS_SCHDLR_SSPND_CHNG_MSB);
-	}
-
-#ifdef ERTS_DIRTY_SCHEDULERS
-	if (!ERTS_SCHEDULER_IS_DIRTY(esdp))
-#endif
-	    ASSERT(no <= *ss_onlinep);
-	ASSERT(!ongoing_multi_scheduling_block());
-
-    }
-
-    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-
-    ASSERT(curr_online);
-
-#ifdef ERTS_DIRTY_SCHEDULERS
-    if (!ERTS_SCHEDULER_IS_DIRTY(esdp))
-#endif
-    {
-	if (erts_system_profile_flags.scheduler)
-	    profile_scheduler(make_small(esdp->no), am_active);
-
-	if (!thr_prgr_active) {
-	    erts_thr_progress_active(esdp, thr_prgr_active = 1);
-	    sched_wall_time_change(esdp, 1);
-	}
-    }
-
-    if (!ERTS_SCHEDULER_IS_DIRTY(esdp))
-	(void) erts_get_monotonic_time(esdp);
-    erts_smp_runq_lock(esdp->run_queue);
-    non_empty_runq(esdp->run_queue);
-
-#ifdef ERTS_DIRTY_SCHEDULERS
-    if (!ERTS_SCHEDULER_IS_DIRTY(esdp))
-#endif
-    {
-	schedule_bound_processes(esdp->run_queue, &sbp);
-
-	erts_sched_check_cpu_bind_post_suspend(esdp);
-    }
-}
-
-#else /* !ERTS_DIRTY_SCHEDULERS */
-
-static void
-suspend_scheduler(ErtsSchedulerData *esdp)
-{
-    erts_aint32_t flgs;
-    erts_aint32_t changing;
-    long no = (long) esdp->no;
-    ErtsSchedulerSleepInfo *ssi = esdp->ssi;
-    long active_schedulers;
-    int curr_online = 1;
-    int wake = 0;
-    erts_aint32_t aux_work;
-    int thr_prgr_active = 1;
-    ErtsStuckBoundProcesses sbp = {NULL, NULL};
-
-    /*
-     * Schedulers may be suspended in two different ways:
-     * - A scheduler may be suspended since it is not online.
-     *   All schedulers with scheduler ids greater than
-     *   schdlr_sspnd.online are suspended.
-     * - Multi scheduling is blocked. All schedulers except the
-     *   scheduler with scheduler id 1 are suspended.
-     *
-     * Regardless of why a scheduler is suspended, it ends up here.
-     */
-
-    ASSERT(no != 1);
-
-    evacuate_run_queue(esdp->run_queue, &sbp);
-
-    erts_smp_runq_unlock(esdp->run_queue);
-
-    erts_sched_check_cpu_bind_prep_suspend(esdp);
-
-    if (erts_system_profile_flags.scheduler)
-    	profile_scheduler(make_small(esdp->no), am_inactive);
-
-    sched_wall_time_change(esdp, 0);
-
-    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-
-    flgs = sched_prep_spin_suspended(ssi, ERTS_SSI_FLG_SUSPENDED);
-    if (flgs & ERTS_SSI_FLG_SUSPENDED) {
-
-	active_schedulers = erts_smp_atomic32_dec_read_nob(&schdlr_sspnd.active);
-	ASSERT(active_schedulers >= 1);
-	changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
-	if (changing & ERTS_SCHDLR_SSPND_CHNG_MSB) {
-	    if (active_schedulers == schdlr_sspnd.msb.wait_active)
-		wake = 1;
-	    if (active_schedulers == 1) {
-		changing = erts_smp_atomic32_read_band_nob(&schdlr_sspnd.changing,
-							   ~ERTS_SCHDLR_SSPND_CHNG_MSB);
-		changing &= ~ERTS_SCHDLR_SSPND_CHNG_MSB;
 	    }
-	}
 
-	while (1) {
-	    if (changing & ERTS_SCHDLR_SSPND_CHNG_ONLN) {
+	    if (changing & online_flag) {
 		int changed = 0;
-		if (no > schdlr_sspnd.online && curr_online) {
-		    schdlr_sspnd.curr_online--;
+		Uint32 st_online;
+
+		st_online = schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,
+						     sched_type);
+		if (no > st_online && curr_online) {
+		    schdlr_sspnd_dec_nscheds(&schdlr_sspnd.curr_online,
+					     sched_type);
 		    curr_online = 0;
 		    changed = 1;
 		}
-		else if (no <= schdlr_sspnd.online && !curr_online) {
-		    schdlr_sspnd.curr_online++;
+		else if (no <= st_online && !curr_online) {
+		    schdlr_sspnd_inc_nscheds(&schdlr_sspnd.curr_online,
+					     sched_type);
 		    curr_online = 1;
 		    changed = 1;
 		}
 		if (changed
-		    && schdlr_sspnd.curr_online == schdlr_sspnd.wait_curr_online)
-		    wake = 1;
-		if (schdlr_sspnd.online == schdlr_sspnd.curr_online) {
+		    && (schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,
+						 sched_type)
+			== schdlr_sspnd_get_nscheds(&schdlr_sspnd.curr_online,
+						    sched_type))) {
+		    ErtsProcList *plp;
 		    changing = erts_smp_atomic32_read_band_nob(&schdlr_sspnd.changing,
-							       ~ERTS_SCHDLR_SSPND_CHNG_ONLN);
-		    changing &= ~ERTS_SCHDLR_SSPND_CHNG_ONLN;
+							       ~online_flag);
+		    changing &= ~online_flag;
+		    if (sched_type == ERTS_SCHED_NORMAL) {
+			ASSERT(is_internal_pid(schdlr_sspnd.changer)
+			       || schdlr_sspnd.changer == am_init);
+			/* resume process that initiated this change... */
+			resume.onln.chngr = schdlr_sspnd.changer;
+			plp = erts_proclist_peek_first(schdlr_sspnd.chngq);
+			if (!plp)
+			    schdlr_sspnd.changer = am_false;
+			else {
+			    schdlr_sspnd.changer = am_true; /* change right in transit */
+			    /* resume process that is queued for next change... */
+			    resume.onln.nxt = plp->pid;
+			    ASSERT(is_internal_pid(resume.onln.nxt));
+			}
+		    }
 		}
 	    }
 
-	    if (wake) {
-		erts_smp_cnd_signal(&schdlr_sspnd.cnd);
-		wake = 0;
-	    }
-
-	    if (curr_online && !ongoing_multi_scheduling_block()) {
+	    if (curr_online
+		&& (sched_type == ERTS_SCHED_NORMAL
+		    ? !(schdlr_sspnd.msb.ongoing|schdlr_sspnd.nmsb.ongoing)
+		    : !schdlr_sspnd.msb.ongoing)) {
 		flgs = erts_smp_atomic32_read_acqb(&ssi->flags);
 		if (!(flgs & ERTS_SSI_FLG_SUSPENDED))
 		    break;
 	    }
 	    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
 
+	    schdlr_sspnd_resume_procs(sched_type, &resume);
+
 	    while (1) {
 		ErtsMonotonicTime current_time;
 		erts_aint32_t qmask;
@@ -7216,9 +7183,23 @@ suspend_scheduler(ErtsSchedulerData *esdp)
 
 		qmask = (ERTS_RUNQ_FLGS_GET(esdp->run_queue)
 			 & ERTS_RUNQ_FLGS_QMASK);
-		aux_work = erts_atomic32_read_acqb(&ssi->aux_work);
-		if (aux_work|qmask) {
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+
+		if (sched_type != ERTS_SCHED_NORMAL) {
+		    if (qmask) {
+			erts_smp_mtx_lock(&schdlr_sspnd.mtx);
+			erts_smp_runq_lock(esdp->run_queue);
+			if (schdlr_sspnd.msb.ongoing)
+			    evacuate_run_queue(esdp->run_queue, &sbp);
+			erts_smp_runq_unlock(esdp->run_queue);
+			erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
+		    }
+		    aux_work = 0;
+		}
+		else {
+
+		    aux_work = erts_atomic32_read_acqb(&ssi->aux_work);
+
+		    if (aux_work|qmask) {
 			if (!thr_prgr_active) {
 			    erts_thr_progress_active(esdp, thr_prgr_active = 1);
 			    sched_wall_time_change(esdp, 1);
@@ -7227,45 +7208,53 @@ suspend_scheduler(ErtsSchedulerData *esdp)
 			    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 (qmask) {
+			    erts_smp_runq_lock(esdp->run_queue);
+			    evacuate_run_queue(esdp->run_queue, &sbp);
+			    erts_smp_runq_unlock(esdp->run_queue);
+			}
 		    }
-		    if (qmask) {
-			erts_smp_runq_lock(esdp->run_queue);
-			evacuate_run_queue(esdp->run_queue, &sbp);
-			erts_smp_runq_unlock(esdp->run_queue);
-		    }
+
 		}
 
 		if (aux_work) {
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
-			current_time = erts_get_monotonic_time(esdp);
-			if (current_time >= erts_next_timeout_time(esdp->next_tmo_ref)) {
-			    if (!thr_prgr_active) {
-				erts_thr_progress_active(esdp, thr_prgr_active = 1);
-				sched_wall_time_change(esdp, 1);
-			    }
-			    erts_bump_timers(esdp->timer_wheel, current_time);
+		    ASSERT(sched_type == ERTS_SCHED_NORMAL);
+		    current_time = erts_get_monotonic_time(esdp);
+		    if (current_time >= erts_next_timeout_time(esdp->next_tmo_ref)) {
+			if (!thr_prgr_active) {
+			    erts_thr_progress_active(esdp, thr_prgr_active = 1);
+			    sched_wall_time_change(esdp, 1);
 			}
+			erts_bump_timers(esdp->timer_wheel, current_time);
 		    }
 		}
 		else {
 		    ErtsMonotonicTime timeout_time;
-		    int do_timeout = 0;
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+		    int do_timeout;
+
+		    if (sched_type == ERTS_SCHED_NORMAL) {
 			timeout_time = erts_check_next_timeout_time(esdp);
 			current_time = erts_get_monotonic_time(esdp);
 			do_timeout = (current_time >= timeout_time);
-		    } else
+		    }
+		    else {
 			timeout_time = ERTS_MONOTONIC_TIME_MAX;
+			current_time = 0;
+			do_timeout = 0;
+		    }
+
 		    if (do_timeout) {
+			ASSERT(sched_type == ERTS_SCHED_NORMAL);
 			if (!thr_prgr_active) {
 			    erts_thr_progress_active(esdp, thr_prgr_active = 1);
 			    sched_wall_time_change(esdp, 1);
 			}
 		    }
 		    else {
-			if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+			if (sched_type == ERTS_SCHED_NORMAL) {
 			    if (thr_prgr_active) {
 				erts_thr_progress_active(esdp, thr_prgr_active = 0);
 				sched_wall_time_change(esdp, 0);
@@ -7284,30 +7273,39 @@ suspend_scheduler(ErtsSchedulerData *esdp)
 					 | ERTS_SSI_FLG_SUSPENDED)) {
 				int res;
 
-				current_time = ERTS_SCHEDULER_IS_DIRTY(esdp) ? 0 :
-				    erts_get_monotonic_time(esdp);
+				if (sched_type == ERTS_SCHED_NORMAL)
+				    current_time = erts_get_monotonic_time(esdp);
+				else
+				    current_time = 0;
+
 				do {
 				    Sint64 timeout;
 				    if (current_time >= timeout_time)
 					break;
-				    if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+				    if (sched_type != ERTS_SCHED_NORMAL)
+					timeout = -1;
+				    else
 					timeout = ERTS_MONOTONIC_TO_NSEC(timeout_time
 									 - current_time
 									 - 1) + 1;
-				    } else
-					timeout = -1;
 				    res = erts_tse_twait(ssi->event, timeout);
-				    current_time = ERTS_SCHEDULER_IS_DIRTY(esdp) ? 0 :
-					erts_get_monotonic_time(esdp);
+
+				    if (sched_type == ERTS_SCHED_NORMAL)
+					current_time = erts_get_monotonic_time(esdp);
+				    else
+					current_time = 0;
+
 				} while (res == EINTR);
 			    }
 			}
-			if (!ERTS_SCHEDULER_IS_DIRTY(esdp))
+			if (sched_type == ERTS_SCHED_NORMAL)
 			    erts_thr_progress_finalize_wait(esdp);
 		    }
 
-		    if (!ERTS_SCHEDULER_IS_DIRTY(esdp) && current_time >= timeout_time)
+		    if (current_time >= timeout_time) {
+			ASSERT(sched_type == ERTS_SCHED_NORMAL);
 			erts_bump_timers(esdp->timer_wheel, current_time);
+		    }
 		}
 
 		flgs = sched_prep_spin_suspended(ssi, (ERTS_SSI_FLG_WAITING
@@ -7315,7 +7313,7 @@ suspend_scheduler(ErtsSchedulerData *esdp)
 		if (!(flgs & ERTS_SSI_FLG_SUSPENDED))
 		    break;
 		changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
-		if (changing & ~ERTS_SCHDLR_SSPND_CHNG_WAITER)
+		if (changing)
 		    break;
 	    }
 
@@ -7323,612 +7321,494 @@ suspend_scheduler(ErtsSchedulerData *esdp)
 	    changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
 	}
 
-	active_schedulers = erts_smp_atomic32_inc_read_nob(&schdlr_sspnd.active);
+	schdlr_sspnd_inc_nscheds(&schdlr_sspnd.active, sched_type);
 	changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
 	if ((changing & ERTS_SCHDLR_SSPND_CHNG_MSB)
-	    && schdlr_sspnd.online == active_schedulers) {
+	    && schdlr_sspnd.online == schdlr_sspnd.active) {
 	    erts_smp_atomic32_read_band_nob(&schdlr_sspnd.changing,
 					    ~ERTS_SCHDLR_SSPND_CHNG_MSB);
 	}
 
-	ASSERT(no <= schdlr_sspnd.online);
-	ASSERT(!ongoing_multi_scheduling_block());
-
+	ASSERT(no <= schdlr_sspnd_get_nscheds(&schdlr_sspnd.online, sched_type));
+	ASSERT((sched_type == ERTS_SCHED_NORMAL
+		? !(schdlr_sspnd.msb.ongoing|schdlr_sspnd.nmsb.ongoing)
+		: !schdlr_sspnd.msb.ongoing));
     }
 
     erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
 
+    ASSERT(!resume.msb.chngrs);
+    schdlr_sspnd_resume_procs(sched_type, &resume);
+
     ASSERT(curr_online);
 
-    if (erts_system_profile_flags.scheduler)
-    	profile_scheduler(make_small(esdp->no), am_active);
+    if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+	if (erts_system_profile_flags.scheduler)
+	    profile_scheduler(make_small(esdp->no), am_active);
 
-    if (!thr_prgr_active) {
-	erts_thr_progress_active(esdp, thr_prgr_active = 1);
-	sched_wall_time_change(esdp, 1);
+	if (!thr_prgr_active) {
+	    erts_thr_progress_active(esdp, thr_prgr_active = 1);
+	    sched_wall_time_change(esdp, 1);
+	}
     }
 
+    if (sched_type == ERTS_SCHED_NORMAL)
+	(void) erts_get_monotonic_time(esdp);
     erts_smp_runq_lock(esdp->run_queue);
     non_empty_runq(esdp->run_queue);
 
-    schedule_bound_processes(esdp->run_queue, &sbp);
+    if (sched_type == ERTS_SCHED_NORMAL) {
+	schedule_bound_processes(esdp->run_queue, &sbp);
 
-    erts_sched_check_cpu_bind_post_suspend(esdp);
+	erts_sched_check_cpu_bind_post_suspend(esdp);
+    }
 }
 
-#endif
-
-ErtsSchedSuspendResult
+void
 erts_schedulers_state(Uint *total,
 		      Uint *online,
 		      Uint *active,
 		      Uint *dirty_cpu,
 		      Uint *dirty_cpu_online,
+		      Uint *dirty_cpu_active,
 		      Uint *dirty_io,
-		      int yield_allowed)
+		      Uint *dirty_io_active)
 {
-    int res = ERTS_SCHDLR_SSPND_EINVAL;
-    erts_aint32_t changing;
-    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-    changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
-#ifdef ERTS_DIRTY_SCHEDULERS
-    changing |= (erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_cpu_changing)
-		 | erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_io_changing));
-#endif
-    if (yield_allowed && (changing & ~ERTS_SCHDLR_SSPND_CHNG_WAITER))
-	res = ERTS_SCHDLR_SSPND_YIELD_RESTART;
-    else {
+    if (active || online || dirty_cpu_online
+	|| dirty_cpu_active || dirty_io_active) {
+	erts_smp_mtx_lock(&schdlr_sspnd.mtx);
 	if (active)
-	    *active = schdlr_sspnd.online;
+	    *active = schdlr_sspnd_get_nscheds(&schdlr_sspnd.active,
+					       ERTS_SCHED_NORMAL);
 	if (online)
-	    *online = schdlr_sspnd.online;
-	if (ongoing_multi_scheduling_block() && active)
-	    *active = 1;
-#ifdef ERTS_DIRTY_SCHEDULERS
+	    *online = schdlr_sspnd_get_nscheds(&schdlr_sspnd.curr_online,
+					       ERTS_SCHED_NORMAL);
+	if (dirty_cpu_active)
+	    *dirty_cpu_active = schdlr_sspnd_get_nscheds(&schdlr_sspnd.active,
+							 ERTS_SCHED_DIRTY_CPU);
 	if (dirty_cpu_online)
-	    *dirty_cpu_online = schdlr_sspnd.dirty_cpu_online;
-#endif
-	res = ERTS_SCHDLR_SSPND_DONE;
+	    *dirty_cpu_online = schdlr_sspnd_get_nscheds(&schdlr_sspnd.curr_online,
+							 ERTS_SCHED_DIRTY_CPU);
+	if (dirty_io_active)
+	    *dirty_io_active = schdlr_sspnd_get_nscheds(&schdlr_sspnd.active,
+							ERTS_SCHED_DIRTY_IO);
+	erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
     }
-    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
+
     if (total)
 	*total = erts_no_schedulers;
-#ifdef ERTS_DIRTY_SCHEDULERS
     if (dirty_cpu)
 	*dirty_cpu = erts_no_dirty_cpu_schedulers;
     if (dirty_io)
 	*dirty_io = erts_no_dirty_io_schedulers;
-#endif
-    return res;
 }
 
-#ifdef ERTS_DIRTY_SCHEDULERS
+static void
+abort_sched_onln_chng_waitq(Process *p)
+{
+    Eterm resume = NIL;
+
+    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
+
+#ifdef DEBUG
+    {
+	int found_it = 0;
+	ErtsProcList *plp = erts_proclist_peek_first(schdlr_sspnd.chngq);
+	while (plp) {
+	    if (erts_proclist_same(plp, p))
+		found_it++;
+	    plp = erts_proclist_peek_next(schdlr_sspnd.chngq, plp);
+	}
+	ASSERT(found_it == !!(p->flags & F_SCHDLR_ONLN_WAITQ));
+    }
+#endif
+
+    if (p->flags & F_SCHDLR_ONLN_WAITQ) {
+	ErtsProcList *plp = NULL;
+
+	plp = erts_proclist_peek_first(schdlr_sspnd.chngq);
+	if (plp) {
+	    if (erts_proclist_same(plp, p)
+		&& schdlr_sspnd.changer == am_true) {
+		p->flags &= ~F_SCHDLR_ONLN_WAITQ;
+		/*
+		 * Change right was in transit to us;
+		 * transfer it to the next process by
+		 * resuming it...
+		 */
+		erts_proclist_remove(&schdlr_sspnd.chngq, plp);
+		proclist_destroy(plp);
+		plp = erts_proclist_peek_first(schdlr_sspnd.chngq);
+		if (plp)
+		    resume = plp->pid;
+		else
+		    schdlr_sspnd.changer = am_false;
+	    }
+	    else {
+		do {
+		    if (erts_proclist_same(plp, p)) {
+			p->flags &= ~F_SCHDLR_ONLN_WAITQ;
+			erts_proclist_remove(&schdlr_sspnd.chngq, plp);
+			proclist_destroy(plp);
+			break;
+		    }
+		    plp = erts_proclist_peek_next(schdlr_sspnd.chngq, plp);
+		} while (plp);
+	    }
+	}
+    }
+
+    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
+
+    if (is_internal_pid(resume))
+	schdlr_sspnd_resume_proc(resume);
+}
 
 ErtsSchedSuspendResult
 erts_set_schedulers_online(Process *p,
 			   ErtsProcLocks plocks,
 			   Sint new_no,
-			   Sint *old_no
-#ifdef ERTS_DIRTY_SCHEDULERS
-			   , int dirty_only
-#endif
-			   )
+			   Sint *old_no,
+			   int dirty_only)
 {
-    ErtsSchedulerData *esdp;
-    int ix, res = -1, no, have_unlocked_plocks, end_wait;
-    erts_aint32_t changing = 0;
+    int resume_proc, ix, res = -1, no, have_unlocked_plocks;
+    erts_aint32_t changing = 0, change_flags;
+    int online, increase;
+    ErtsProcList *plp;
 #ifdef ERTS_DIRTY_SCHEDULERS
-    ErtsSchedulerSleepInfo* ssi;
-    int dirty_no, change_dirty;
+    int dirty_no, change_dirty, dirty_online;
+#else
+    ASSERT(!dirty_only);
 #endif
 
     if (new_no < 1)
 	return ERTS_SCHDLR_SSPND_EINVAL;
-#ifdef ERTS_DIRTY_SCHEDULERS
     else if (dirty_only && erts_no_dirty_cpu_schedulers < new_no)
 	return ERTS_SCHDLR_SSPND_EINVAL;
-#endif
     else if (erts_no_schedulers < new_no)
 	return ERTS_SCHDLR_SSPND_EINVAL;
 
-    esdp = ERTS_PROC_GET_SCHDATA(p);
-    end_wait = 0;
+#ifdef ERTS_DIRTY_SCHEDULERS
+    if (dirty_only)
+	resume_proc = 0;
+    else
+#endif
+    {
+	resume_proc = 1;
+	/*
+	 * If we suspend current process we need to suspend before
+	 * requesting the change; otherwise, we got a resume/suspend
+	 * race...
+	 */
+	if (!(plocks & ERTS_PROC_LOCK_STATUS))
+	    erts_smp_proc_lock(p, ERTS_PROC_LOCK_STATUS);
+	suspend_process(p, p);
+	if (!(plocks & ERTS_PROC_LOCK_STATUS))
+	    erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
+    }
 
     erts_smp_mtx_lock(&schdlr_sspnd.mtx);
 
+    change_flags = 0;
     have_unlocked_plocks = 0;
     no = (int) new_no;
 
 #ifdef ERTS_DIRTY_SCHEDULERS
-    ASSERT(schdlr_sspnd.dirty_cpu_online <= erts_no_dirty_cpu_schedulers);
+    if (!dirty_only)
+#endif
+    {
+	changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
+	if (changing & ERTS_SCHDLR_SSPND_CHNG_ONLN) {
+	enqueue_wait:
+	    p->flags |= F_SCHDLR_ONLN_WAITQ;
+	    plp = proclist_create(p);
+	    erts_proclist_store_last(&schdlr_sspnd.chngq, plp);
+	    resume_proc = 0;
+	    res = ERTS_SCHDLR_SSPND_YIELD_RESTART;
+	    goto done;
+	}
+	plp = erts_proclist_peek_first(schdlr_sspnd.chngq);
+	if (!plp) {
+	    ASSERT(schdlr_sspnd.changer == am_false);
+	}
+	else {
+	    ASSERT(schdlr_sspnd.changer == am_true);
+	    if (!erts_proclist_same(plp, p))
+		goto enqueue_wait;
+	    p->flags &= ~F_SCHDLR_ONLN_WAITQ;
+	    erts_proclist_remove(&schdlr_sspnd.chngq, plp);
+	    proclist_destroy(plp);
+	}
+    }
+
+    *old_no = online = schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,
+						ERTS_SCHED_NORMAL);
+#ifndef ERTS_DIRTY_SCHEDULERS
+    if (no == online) {
+	res = ERTS_SCHDLR_SSPND_DONE;
+	goto done;
+    }
+#else /* ERTS_DIRTY_SCHEDULERS */
+    dirty_online = schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,
+					    ERTS_SCHED_DIRTY_CPU);
+    if (dirty_only)
+	*old_no = dirty_online;
+
+    ASSERT(dirty_online <= erts_no_dirty_cpu_schedulers);
+
     if (dirty_only) {
-	if (no > schdlr_sspnd.online) {
-	    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-	    return ERTS_SCHDLR_SSPND_EINVAL;
+	if (no > online) {
+	    res = ERTS_SCHDLR_SSPND_EINVAL;
+	    goto done;
 	}
 	dirty_no = no;
+	if (dirty_no == dirty_online) {
+	    res = ERTS_SCHDLR_SSPND_DONE;
+	    goto done;
+	}
+	change_dirty = 1;
     } else {
 	/*
 	 * Adjust the number of dirty CPU schedulers online relative to the
 	 * adjustment made to the number of normal schedulers online.
 	 */
 	int total_pct = erts_no_dirty_cpu_schedulers*100/erts_no_schedulers;
-	int onln_pct = no*total_pct/schdlr_sspnd.online;
-	dirty_no = schdlr_sspnd.dirty_cpu_online*onln_pct/100;
+	int onln_pct = no*total_pct/online;
+	dirty_no = dirty_online*onln_pct/100;
 	if (dirty_no == 0)
 	    dirty_no = 1;
 	ASSERT(dirty_no <= erts_no_dirty_cpu_schedulers);
-    }
-#endif
-    changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
-#ifdef ERTS_DIRTY_SCHEDULERS
-    changing |= erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_cpu_changing);
-#endif
-    if (changing) {
-	res = ERTS_SCHDLR_SSPND_YIELD_RESTART;
-    }
-    else {
-	int online = *old_no = schdlr_sspnd.online;
-#ifdef ERTS_DIRTY_SCHEDULERS
-	int dirty_online = schdlr_sspnd.dirty_cpu_online;
 
-	if (dirty_only) {
-	    *old_no = schdlr_sspnd.dirty_cpu_online;
-	    if (dirty_no == schdlr_sspnd.dirty_cpu_online) {
+	if (no != online)
+	    change_dirty = (dirty_no != dirty_online);
+	else {
+	    dirty_only = 1;
+	    if (dirty_no == dirty_online) {
 		res = ERTS_SCHDLR_SSPND_DONE;
+		goto done;
 	    }
 	    change_dirty = 1;
-	} else {
-#endif
-	    if (no == schdlr_sspnd.online) {
-#ifdef ERTS_DIRTY_SCHEDULERS
-		dirty_only = 1;
-		if (dirty_no == schdlr_sspnd.dirty_cpu_online)
-#endif
-		    res = ERTS_SCHDLR_SSPND_DONE;
-#ifdef ERTS_DIRTY_SCHEDULERS
-		else
-		    change_dirty = 1;
-#endif
-	    }
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    else
-		change_dirty = (dirty_no != schdlr_sspnd.dirty_cpu_online);
 	}
-#endif
-	if (res == -1)
-	{
-	    int increase = (no > online);
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    if (!dirty_only) {
-#endif
-		ERTS_SCHDLR_SSPND_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_ONLN
-					    | ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
-		schdlr_sspnd.online = no;
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    } else
-		increase = (dirty_no > dirty_online);
-	    if (change_dirty) {
-		ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_ONLN
-						      | ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
-		schdlr_sspnd.dirty_cpu_online = dirty_no;
-	    }
-#endif
-	    if (increase) {
-		int ix;
-#ifdef ERTS_DIRTY_SCHEDULERS
-		if (!dirty_only) {
-#endif
-		    schdlr_sspnd.wait_curr_online = no;
-		    if (ongoing_multi_scheduling_block()) {
-			for (ix = online; ix < no; ix++)
-			    erts_sched_poke(ERTS_SCHED_SLEEP_INFO_IX(ix));
-		    }
-		    else {
-			if (plocks) {
-			    have_unlocked_plocks = 1;
-			    erts_smp_proc_unlock(p, plocks);
-			}
-			change_no_used_runqs(no);
+    }
+    if (change_dirty) {
+	change_flags |= ERTS_SCHDLR_SSPND_CHNG_DCPU_ONLN;
+	schdlr_sspnd_set_nscheds(&schdlr_sspnd.online,
+				 ERTS_SCHED_DIRTY_CPU,
+				 dirty_no);
+    }
 
-			for (ix = online; ix < no; ix++)
-			    resume_run_queue(ERTS_RUNQ_IX(ix));
+    if (dirty_only)
+	increase = (dirty_no > dirty_online);
+    else
+#endif /* ERTS_DIRTY_SCHEDULERS */
+    {
+	change_flags |= ERTS_SCHDLR_SSPND_CHNG_ONLN;
+	schdlr_sspnd_set_nscheds(&schdlr_sspnd.online,
+				 ERTS_SCHED_NORMAL,
+				 no);
+	increase = (no > online);
+    }
 
-			for (ix = no; ix < erts_no_run_queues; ix++)
-			    suspend_run_queue(ERTS_RUNQ_IX(ix));
-		    }
+    erts_smp_atomic32_read_bor_nob(&schdlr_sspnd.changing, change_flags);
+
+    res = ERTS_SCHDLR_SSPND_DONE;
+    if (increase) {
+	int ix;
 #ifdef ERTS_DIRTY_SCHEDULERS
+	if (change_dirty) {
+	    ErtsSchedulerSleepInfo* ssi;
+	    if (schdlr_sspnd.msb.ongoing) {
+		for (ix = dirty_online; ix < dirty_no; ix++) {
+		    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
+		    erts_sched_poke(ssi);
 		}
-		if (change_dirty) {
-		    schdlr_sspnd.dirty_cpu_wait_curr_online = dirty_no;
-		    ASSERT(schdlr_sspnd.dirty_cpu_curr_online !=
-			   schdlr_sspnd.dirty_cpu_wait_curr_online);
-		    if (ongoing_multi_scheduling_block()) {
-			for (ix = dirty_online; ix < dirty_no; ix++) {
-			    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
-			    erts_sched_poke(ssi);
-			}
-		    } else {
-			for (ix = dirty_online; ix < dirty_no; ix++) {
-			    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
-			    scheduler_ssi_resume_wake(ssi);
-			    erts_smp_atomic32_read_band_nob(&ssi->flags,
-							    ~ERTS_SSI_FLG_SUSPENDED);
-			}
-			wake_dirty_schedulers(ERTS_DIRTY_CPU_RUNQ, 0);
-		    }
+	    } else {
+		for (ix = dirty_online; ix < dirty_no; ix++) {
+		    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
+		    scheduler_ssi_resume_wake(ssi);
 		}
-#endif
-		res = ERTS_SCHDLR_SSPND_DONE;
 	    }
-	    else /* if (no < online) */ {
-#ifdef ERTS_DIRTY_SCHEDULERS
-		if (change_dirty) {
-		    schdlr_sspnd.dirty_cpu_wait_curr_online = dirty_no;
-		    ASSERT(schdlr_sspnd.dirty_cpu_curr_online !=
-			   schdlr_sspnd.dirty_cpu_wait_curr_online);
-		    if (ongoing_multi_scheduling_block()) {
-			for (ix = dirty_no; ix < dirty_online; ix++) {
-			    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
-			    erts_sched_poke(ssi);
-			}
-		    } else {
-			for (ix = dirty_no; ix < dirty_online; ix++) {
-			    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
-			    erts_smp_atomic32_read_bor_nob(&ssi->flags,
-							   ERTS_SSI_FLG_SUSPENDED);
-			}
-			wake_dirty_schedulers(ERTS_DIRTY_CPU_RUNQ, 0);
-		    }
-		}
-		if (dirty_only) {
-		    res = ERTS_SCHDLR_SSPND_DONE;
-		}
-		else
+	}
+	if (!dirty_only)
 #endif
-		{
-		    if (p->scheduler_data->no <= no) {
-			res = ERTS_SCHDLR_SSPND_DONE;
-			schdlr_sspnd.wait_curr_online = no;
-		    }
-		    else {
-			/*
-			 * Yield! Current process needs to migrate
-			 * before bif returns.
-			 */
-			res = ERTS_SCHDLR_SSPND_YIELD_DONE;
-			schdlr_sspnd.wait_curr_online = no+1;
-		    }
-
-		    if (ongoing_multi_scheduling_block()) {
-			for (ix = no; ix < online; ix++)
-			    erts_sched_poke(ERTS_SCHED_SLEEP_INFO_IX(ix));
-		    }
-		    else {
-			if (plocks) {
-			    have_unlocked_plocks = 1;
-			    erts_smp_proc_unlock(p, plocks);
-			}
-
-			change_no_used_runqs(no);
-			for (ix = no; ix < erts_no_run_queues; ix++)
-			    suspend_run_queue(ERTS_RUNQ_IX(ix));
-
-			for (ix = no; ix < online; ix++) {
-			    ErtsRunQueue *rq = ERTS_RUNQ_IX(ix);
-			    wake_scheduler(rq);
-			}
-		    }
-		}
+	{
+	    if (schdlr_sspnd.msb.ongoing|schdlr_sspnd.nmsb.ongoing) {
+		for (ix = online; ix < no; ix++)
+		    erts_sched_poke(ERTS_SCHED_SLEEP_INFO_IX(ix));
 	    }
-
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    if (change_dirty) {
-		while (schdlr_sspnd.dirty_cpu_curr_online != schdlr_sspnd.dirty_cpu_wait_curr_online)
-		    erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
-		ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET(0, ERTS_SCHDLR_SSPND_CHNG_WAITER);
-		erts_smp_atomic32_read_band_nob(&schdlr_sspnd.dirty_cpu_changing,
-						~ERTS_SCHDLR_SSPND_CHNG_WAITER);
-	    }
-	    if (!dirty_only)
-#endif
-	    {
-		if (schdlr_sspnd.curr_online != schdlr_sspnd.wait_curr_online) {
-		    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-		    if (plocks && !have_unlocked_plocks) {
-			have_unlocked_plocks = 1;
-			erts_smp_proc_unlock(p, plocks);
-		    }
-		    erts_thr_progress_active(esdp, 0);
-		    erts_thr_progress_prepare_wait(esdp);
-		    end_wait = 1;
-		    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
+	    else {
+		if (plocks) {
+		    have_unlocked_plocks = 1;
+		    erts_smp_proc_unlock(p, plocks);
 		}
+		change_no_used_runqs(no);
 
-		while (schdlr_sspnd.curr_online != schdlr_sspnd.wait_curr_online)
-		    erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
+		for (ix = online; ix < no; ix++)
+		    resume_run_queue(ERTS_RUNQ_IX(ix));
 
-		ASSERT(res != ERTS_SCHDLR_SSPND_DONE
-		       ? (ERTS_SCHDLR_SSPND_CHNG_WAITER
-			  & erts_smp_atomic32_read_nob(&schdlr_sspnd.changing))
-		       : (ERTS_SCHDLR_SSPND_CHNG_WAITER
-			  == erts_smp_atomic32_read_nob(&schdlr_sspnd.changing)));
-		erts_smp_atomic32_read_band_nob(&schdlr_sspnd.changing,
-						~ERTS_SCHDLR_SSPND_CHNG_WAITER);
+		for (ix = no; ix < erts_no_run_queues; ix++)
+		    suspend_run_queue(ERTS_RUNQ_IX(ix));
 	    }
 	}
     }
-
-    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
+    else /* if decrease */ {
 #ifdef ERTS_DIRTY_SCHEDULERS
-    ASSERT(schdlr_sspnd.dirty_cpu_online <= schdlr_sspnd.online);
-    if (!dirty_only)
-#endif
-    {
-	if (end_wait) {
-	    erts_thr_progress_finalize_wait(esdp);
-	    erts_thr_progress_active(esdp, 1);
-	}
-	if (have_unlocked_plocks)
-	    erts_smp_proc_lock(p, plocks);
-    }
-
-    return res;
-}
-
-#else /* !ERTS_DIRTY_SCHEDULERS */
-
-ErtsSchedSuspendResult
-erts_set_schedulers_online(Process *p,
-			   ErtsProcLocks plocks,
-			   Sint new_no,
-			   Sint *old_no)
-{
-    ErtsSchedulerData *esdp;
-    int ix, res, no, have_unlocked_plocks, end_wait;
-    erts_aint32_t changing;
-
-    if (new_no < 1 || erts_no_schedulers < new_no)
-	return ERTS_SCHDLR_SSPND_EINVAL;
-
-    esdp = ERTS_PROC_GET_SCHDATA(p);
-    end_wait = 0;
-
-    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-
-    have_unlocked_plocks = 0;
-    no = (int) new_no;
-
-    changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
-    if (changing) {
-	res = ERTS_SCHDLR_SSPND_YIELD_RESTART;
-    }
-    else {
-	int online = *old_no = schdlr_sspnd.online;
-	if (no == schdlr_sspnd.online) {
-	    res = ERTS_SCHDLR_SSPND_DONE;
-	}
-	else {
-	    ERTS_SCHDLR_SSPND_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_ONLN
-					| ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
-	    schdlr_sspnd.online = no;
-	    if (no > online) {
-		int ix;
-		schdlr_sspnd.wait_curr_online = no;
-		if (ongoing_multi_scheduling_block()) {
-		    for (ix = online; ix < no; ix++)
-			erts_sched_poke(ERTS_SCHED_SLEEP_INFO_IX(ix));
+	if (change_dirty) {
+	    ErtsSchedulerSleepInfo* ssi;
+	    if (schdlr_sspnd.msb.ongoing) {
+		for (ix = dirty_no; ix < dirty_online; ix++) {
+		    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
+		    erts_sched_poke(ssi);
 		}
-		else {
-		    if (plocks) {
-			have_unlocked_plocks = 1;
-			erts_smp_proc_unlock(p, plocks);
-		    }
-		    change_no_used_runqs(no);
-
-		    for (ix = online; ix < no; ix++)
-			resume_run_queue(ERTS_RUNQ_IX(ix));
-
-		    for (ix = no; ix < erts_no_run_queues; ix++)
-			suspend_run_queue(ERTS_RUNQ_IX(ix));
+	    } else {
+		for (ix = dirty_no; ix < dirty_online; ix++) {
+		    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
+		    erts_smp_atomic32_read_bor_nob(&ssi->flags,
+						   ERTS_SSI_FLG_SUSPENDED);
 		}
-		res = ERTS_SCHDLR_SSPND_DONE;
+		wake_dirty_schedulers(ERTS_DIRTY_CPU_RUNQ, 0);
 	    }
-	    else /* if (no < online) */ {
-		if (p->scheduler_data->no <= no) {
-		    res = ERTS_SCHDLR_SSPND_DONE;
-		    schdlr_sspnd.wait_curr_online = no;
-		}
-		else {
-		    /*
-		     * Yield! Current process needs to migrate
-		     * before bif returns.
-		     */
-		    res = ERTS_SCHDLR_SSPND_YIELD_DONE;
-		    schdlr_sspnd.wait_curr_online = no+1;
-		}
-
-		if (ongoing_multi_scheduling_block()) {
-		    for (ix = no; ix < online; ix++)
-			erts_sched_poke(ERTS_SCHED_SLEEP_INFO_IX(ix));
-		}
-		else {
-		    if (plocks) {
-			have_unlocked_plocks = 1;
-			erts_smp_proc_unlock(p, plocks);
-		    }
-
-		    change_no_used_runqs(no);
-		    for (ix = no; ix < erts_no_run_queues; ix++)
-			suspend_run_queue(ERTS_RUNQ_IX(ix));
-
-		    for (ix = no; ix < online; ix++) {
-			ErtsRunQueue *rq = ERTS_RUNQ_IX(ix);
-			wake_scheduler(rq);
-		    }
-		}
+	}
+	if (!dirty_only)
+#endif
+	{
+	    if (schdlr_sspnd.msb.ongoing|schdlr_sspnd.nmsb.ongoing) {
+		for (ix = no; ix < online; ix++)
+		    erts_sched_poke(ERTS_SCHED_SLEEP_INFO_IX(ix));
 	    }
-
-	    if (schdlr_sspnd.curr_online != schdlr_sspnd.wait_curr_online) {
-		erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-		if (plocks && !have_unlocked_plocks) {
+	    else {
+		if (plocks) {
 		    have_unlocked_plocks = 1;
 		    erts_smp_proc_unlock(p, plocks);
 		}
-		erts_thr_progress_active(esdp, 0);
-		erts_thr_progress_prepare_wait(esdp);
-		end_wait = 1;
-		erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-	    }
-
-	    while (schdlr_sspnd.curr_online != schdlr_sspnd.wait_curr_online)
-		erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
 
-	    ASSERT(res != ERTS_SCHDLR_SSPND_DONE
-		   ? (ERTS_SCHDLR_SSPND_CHNG_WAITER
-		      & erts_smp_atomic32_read_nob(&schdlr_sspnd.changing))
-		   : (ERTS_SCHDLR_SSPND_CHNG_WAITER
-		      == erts_smp_atomic32_read_nob(&schdlr_sspnd.changing)));
-	    erts_smp_atomic32_read_band_nob(&schdlr_sspnd.changing,
-					    ~ERTS_SCHDLR_SSPND_CHNG_WAITER);
+		change_no_used_runqs(no);
+		for (ix = no; ix < erts_no_run_queues; ix++)
+		    suspend_run_queue(ERTS_RUNQ_IX(ix));
 
+		for (ix = no; ix < online; ix++) {
+		    ErtsRunQueue *rq = ERTS_RUNQ_IX(ix);
+		    wake_scheduler(rq);
+		}
+	    }
 	}
     }
 
-    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-    if (end_wait) {
-	erts_thr_progress_finalize_wait(esdp);
-	erts_thr_progress_active(esdp, 1);
+    if (change_flags & ERTS_SCHDLR_SSPND_CHNG_ONLN) {
+	/* Suspend and wait for requested change to complete... */
+	schdlr_sspnd.changer = p->common.id;
+	resume_proc = 0;
+	res = ERTS_SCHDLR_SSPND_YIELD_DONE;
     }
+
+done:
+
+    ASSERT(schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,
+				    ERTS_SCHED_DIRTY_CPU)
+	   <= schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,
+				       ERTS_SCHED_NORMAL));
+
+    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
+
     if (have_unlocked_plocks)
 	erts_smp_proc_lock(p, plocks);
 
+    if (resume_proc) {
+	if (!(plocks & ERTS_PROC_LOCK_STATUS))
+	    erts_smp_proc_lock(p, ERTS_PROC_LOCK_STATUS);
+	resume_process(p, plocks|ERTS_PROC_LOCK_STATUS);
+	if (!(plocks & ERTS_PROC_LOCK_STATUS))
+	    erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
+    }
+
     return res;
 }
 
-#endif
-
 ErtsSchedSuspendResult
-erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all)
+erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int normal, int all)
 {
-    int ix, res, have_unlocked_plocks = 0, online;
-    erts_aint32_t changing;
+    int resume_proc, ix, res, have_unlocked_plocks = 0;
     ErtsProcList *plp;
 #ifdef ERTS_DIRTY_SCHEDULERS
     ErtsSchedulerSleepInfo* ssi;
 #endif
+    ErtsMultiSchedulingBlock *msbp;
+    erts_aint32_t chng_flg;
+    int have_blckd_flg;
 
-    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-    changing = erts_smp_atomic32_read_nob(&schdlr_sspnd.changing);
-#ifdef ERTS_DIRTY_SCHEDULERS
-    changing |= (erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_cpu_changing)
-		 | erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_io_changing));
-#endif
-    if (changing) {
-	res = ERTS_SCHDLR_SSPND_YIELD_RESTART; /* Yield */
+    if (normal) {
+	chng_flg = ERTS_SCHDLR_SSPND_CHNG_NMSB;
+	have_blckd_flg = F_HAVE_BLCKD_NMSCHED;
+	msbp = &schdlr_sspnd.nmsb;
+    }
+    else {
+	chng_flg = ERTS_SCHDLR_SSPND_CHNG_MSB;
+	have_blckd_flg = F_HAVE_BLCKD_MSCHED;
+	msbp = &schdlr_sspnd.msb;
+    }
+
+    /*
+     * If we suspend current process we need to suspend before
+     * requesting the change; otherwise, we got a resume/suspend
+     * race...
+     */
+    if (!on) {
+	/* We never suspend current process when unblocking... */
+	resume_proc = 0;
     }
-    else if (on) { /* ------ BLOCK ------ */
-	if (schdlr_sspnd.msb.procs) {
+    else {
+	resume_proc = 1;
+	if (!(plocks & ERTS_PROC_LOCK_STATUS))
+	    erts_smp_proc_lock(p, ERTS_PROC_LOCK_STATUS);
+	suspend_process(p, p);
+	if (!(plocks & ERTS_PROC_LOCK_STATUS))
+	    erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
+    }
+
+    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
+    if (on) { /* ------ BLOCK ------ */
+	if (msbp->chngq) {
+	    ASSERT(msbp->ongoing);
+	    p->flags |= have_blckd_flg;
+	    goto wait_until_msb;
+	}
+	else if (msbp->blckrs) {
+	    ASSERT(msbp->ongoing);
 	    plp = proclist_create(p);
-	    erts_proclist_store_last(&schdlr_sspnd.msb.procs, plp);
-	    p->flags |= F_HAVE_BLCKD_MSCHED;
-	    ASSERT(erts_smp_atomic32_read_nob(&schdlr_sspnd.active) == 1);
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    ASSERT(erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_cpu_active) == 0);
-	    ASSERT(erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_io_active) == 0);
-#endif
+	    erts_proclist_store_last(&msbp->blckrs, plp);
+	    p->flags |= have_blckd_flg;
+	    ASSERT(schdlr_sspnd.active == ERTS_SCHDLR_SSPND_MAKE_NSCHEDS_VAL(1, 0, 0));
 	    ASSERT(p->scheduler_data->no == 1);
-	    res = ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED;
-	} else {
-	    int online = schdlr_sspnd.online;
-	    p->flags |= F_HAVE_BLCKD_MSCHED;
+	    if (schdlr_sspnd.msb.ongoing)
+		res = ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED;
+	    else
+		res = ERTS_SCHDLR_SSPND_DONE_NMSCHED_BLOCKED;
+	}
+	else {
+	    int online = (int) schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,
+							ERTS_SCHED_NORMAL);
+	    ASSERT(!msbp->ongoing);
+	    p->flags |= have_blckd_flg;
 	    if (plocks) {
 		have_unlocked_plocks = 1;
 		erts_smp_proc_unlock(p, plocks);
 	    }
-	    ASSERT(!ongoing_multi_scheduling_block());
-	    schdlr_sspnd.msb.ongoing = 1;
-	    if (online == 1) {
-		res = ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED;
-		ASSERT(erts_smp_atomic32_read_nob(&schdlr_sspnd.active) == 1);
-#ifdef ERTS_DIRTY_SCHEDULERS
-		ASSERT(erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_cpu_active) == 1);
-		ASSERT(!(erts_smp_atomic32_read_nob(&ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(0)->flags)
-			 & ERTS_SSI_FLG_SUSPENDED));
-		schdlr_sspnd.msb.dirty_cpu_wait_active = 0;
-		ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_MSB
-						      | ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
-		ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(0);
-		erts_smp_atomic32_read_bor_nob(&ssi->flags, ERTS_SSI_FLG_SUSPENDED);
-		wake_dirty_schedulers(ERTS_DIRTY_CPU_RUNQ, 0);
-		while (erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_cpu_active)
-		       != schdlr_sspnd.msb.dirty_cpu_wait_active)
-		    erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
-		ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET(0, ERTS_SCHDLR_SSPND_CHNG_WAITER);
-
-		schdlr_sspnd.msb.dirty_io_wait_active = 0;
-		ERTS_SCHDLR_SSPND_DIRTY_IO_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_MSB
-						     | ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
-		for (ix = 0; ix < erts_no_dirty_io_schedulers; ix++) {
-		    ssi = ERTS_DIRTY_IO_SCHED_SLEEP_INFO_IX(ix);
-		    erts_smp_atomic32_read_bor_nob(&ssi->flags,
-						   ERTS_SSI_FLG_SUSPENDED);
-		}
-		wake_dirty_schedulers(ERTS_DIRTY_IO_RUNQ, 0);
-		while (erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_io_active)
-		       != schdlr_sspnd.msb.dirty_io_wait_active)
-		    erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
-		ERTS_SCHDLR_SSPND_DIRTY_IO_CHNG_SET(0, ERTS_SCHDLR_SSPND_CHNG_WAITER);
-#endif
+	    ASSERT(!msbp->ongoing);
+	    msbp->ongoing = 1;
+	    if (schdlr_sspnd.active == ERTS_SCHDLR_SSPND_MAKE_NSCHEDS_VAL(1, 0, 0)
+		|| (normal && schdlr_sspnd_get_nscheds(&schdlr_sspnd.active,
+						       ERTS_SCHED_NORMAL) == 1)) {
 		ASSERT(p->scheduler_data->no == 1);
+		plp = proclist_create(p);
+		erts_proclist_store_last(&msbp->blckrs, plp);
+		if (schdlr_sspnd.msb.ongoing)
+		    res = ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED;
+		else
+		    res = ERTS_SCHDLR_SSPND_DONE_NMSCHED_BLOCKED;
 	    }
 	    else {
-		ERTS_SCHDLR_SSPND_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_MSB
-					    | ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
-		if (p->scheduler_data->no == 1) {
-		    res = ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED;
-		    schdlr_sspnd.msb.wait_active = 1;
-		}
-		else {
-		    /*
-		     * Yield! Current process needs to migrate
-		     * before bif returns.
-		     */
-		    res = ERTS_SCHDLR_SSPND_YIELD_DONE_MSCHED_BLOCKED;
-		    schdlr_sspnd.msb.wait_active = 2;
-		}
-
-#ifdef ERTS_DIRTY_SCHEDULERS
-		schdlr_sspnd.msb.dirty_cpu_wait_active = 0;
-		ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_MSB
-						      | ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
-		for (ix = 0; ix < erts_no_dirty_cpu_schedulers; ix++) {
-		    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
-		    erts_smp_atomic32_read_bor_nob(&ssi->flags,
-						   ERTS_SSI_FLG_SUSPENDED);
-		}
-		wake_dirty_schedulers(ERTS_DIRTY_CPU_RUNQ, 0);
-		while (erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_cpu_active)
-		       != schdlr_sspnd.msb.dirty_cpu_wait_active)
-		    erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
-		ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET(0, ERTS_SCHDLR_SSPND_CHNG_WAITER);
-		ASSERT(schdlr_sspnd.dirty_cpu_curr_online == schdlr_sspnd.dirty_cpu_online);
-
-		schdlr_sspnd.msb.dirty_io_wait_active = 0;
-		ERTS_SCHDLR_SSPND_DIRTY_IO_CHNG_SET((ERTS_SCHDLR_SSPND_CHNG_MSB
-						     | ERTS_SCHDLR_SSPND_CHNG_WAITER), 0);
-		for (ix = 0; ix < erts_no_dirty_io_schedulers; ix++) {
-		    ssi = ERTS_DIRTY_IO_SCHED_SLEEP_INFO_IX(ix);
-		    erts_smp_atomic32_read_bor_nob(&ssi->flags,
-						   ERTS_SSI_FLG_SUSPENDED);
-		}
-		wake_dirty_schedulers(ERTS_DIRTY_IO_RUNQ, 0);
-		while (erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_io_active)
-		       != schdlr_sspnd.msb.dirty_io_wait_active)
-		    erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
-		ERTS_SCHDLR_SSPND_DIRTY_IO_CHNG_SET(0, ERTS_SCHDLR_SSPND_CHNG_WAITER);
-		ASSERT(schdlr_sspnd.dirty_io_curr_online == schdlr_sspnd.dirty_io_online);
-#endif
+		erts_smp_atomic32_read_bor_nob(&schdlr_sspnd.changing,
+					       chng_flg);
 		change_no_used_runqs(1);
 		for (ix = 1; ix < erts_no_run_queues; ix++)
 		    suspend_run_queue(ERTS_RUNQ_IX(ix));
@@ -7938,84 +7818,84 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all)
 		    wake_scheduler(rq);
 		}
 
-		if (erts_smp_atomic32_read_nob(&schdlr_sspnd.active)
-		    != schdlr_sspnd.msb.wait_active) {
-		    ErtsSchedulerData *esdp;
-
-		    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-
-		    if (plocks && !have_unlocked_plocks) {
-			have_unlocked_plocks = 1;
-			erts_smp_proc_unlock(p, plocks);
+#ifdef ERTS_DIRTY_SCHEDULERS
+		if (!normal) {
+		    for (ix = 0; ix < erts_no_dirty_cpu_schedulers; ix++) {
+			ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
+			erts_smp_atomic32_read_bor_nob(&ssi->flags,
+						       ERTS_SSI_FLG_SUSPENDED);
 		    }
+		    wake_dirty_schedulers(ERTS_DIRTY_CPU_RUNQ, 0);
 
-		    esdp = ERTS_PROC_GET_SCHDATA(p);
-
-		    erts_thr_progress_active(esdp, 0);
-		    erts_thr_progress_prepare_wait(esdp);
-
-		    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-
-		    while (erts_smp_atomic32_read_nob(&schdlr_sspnd.active)
-			   != schdlr_sspnd.msb.wait_active)
-			erts_smp_cnd_wait(&schdlr_sspnd.cnd,
-					  &schdlr_sspnd.mtx);
-		    
-		    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-		    
-		    erts_thr_progress_active(esdp, 1);
-		    erts_thr_progress_finalize_wait(esdp);
+		    for (ix = 0; ix < erts_no_dirty_io_schedulers; ix++) {
+			ssi = ERTS_DIRTY_IO_SCHED_SLEEP_INFO_IX(ix);
+			erts_smp_atomic32_read_bor_nob(&ssi->flags,
+						       ERTS_SSI_FLG_SUSPENDED);
+		    }
+		    wake_dirty_schedulers(ERTS_DIRTY_IO_RUNQ, 0);
+		}
+#endif
 
-		    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
+	    wait_until_msb:
 
-		}
+		ASSERT(chng_flg & erts_smp_atomic32_read_nob(&schdlr_sspnd.changing));
 
-		ASSERT(res != ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED
-		       ? (ERTS_SCHDLR_SSPND_CHNG_WAITER
-			  & erts_smp_atomic32_read_nob(&schdlr_sspnd.changing))
-		       : (ERTS_SCHDLR_SSPND_CHNG_WAITER
-			  == erts_smp_atomic32_read_nob(&schdlr_sspnd.changing)));
-		erts_smp_atomic32_read_band_nob(&schdlr_sspnd.changing,
-						~ERTS_SCHDLR_SSPND_CHNG_WAITER);
+		plp = proclist_create(p);
+		erts_proclist_store_last(&msbp->chngq, plp);
+		resume_proc = 0;
+		if (schdlr_sspnd.msb.ongoing)
+		    res = ERTS_SCHDLR_SSPND_YIELD_DONE_MSCHED_BLOCKED;
+		else
+		    res = ERTS_SCHDLR_SSPND_YIELD_DONE_NMSCHED_BLOCKED;
 	    }
-	    plp = proclist_create(p);
-	    erts_proclist_store_last(&schdlr_sspnd.msb.procs, plp);
 	    ASSERT(p->scheduler_data);
 	}
     }
-    else if (!ongoing_multi_scheduling_block()) {
-	/* unblock not ongoing */
-	ASSERT(!schdlr_sspnd.msb.procs);
-	res = ERTS_SCHDLR_SSPND_DONE;
+    else if (!msbp->ongoing) {
+	ASSERT(!msbp->blckrs);
+	goto unblock_res;
     }
     else {  /* ------ UNBLOCK ------ */
-	if (p->flags & F_HAVE_BLCKD_MSCHED) {
-	    ErtsProcList *plp = erts_proclist_peek_first(schdlr_sspnd.msb.procs);
-
-	    while (plp) {
-		ErtsProcList *tmp_plp = plp;
-		plp = erts_proclist_peek_next(schdlr_sspnd.msb.procs, plp);
-		if (erts_proclist_same(tmp_plp, p)) {
-		    erts_proclist_remove(&schdlr_sspnd.msb.procs, tmp_plp);
-		    proclist_destroy(tmp_plp);
-		    if (!all)
-			break;
+	if (p->flags & have_blckd_flg) {
+	    ErtsProcList *plps[2];
+	    ErtsProcList *plp;
+	    int limit = 0;
+
+	    plps[limit++] = erts_proclist_peek_first(msbp->blckrs);
+	    if (all)
+		plps[limit++] = erts_proclist_peek_first(msbp->chngq);
+
+	    for (ix = 0; ix < limit; ix++) {
+		plp = plps[ix];
+		while (plp) {
+		    ErtsProcList *tmp_plp = plp;
+		    plp = erts_proclist_peek_next(msbp->blckrs, plp);
+		    if (erts_proclist_same(tmp_plp, p)) {
+			erts_proclist_remove(&msbp->blckrs, tmp_plp);
+			proclist_destroy(tmp_plp);
+			if (!all)
+			    break;
+		    }
 		}
 	    }
 	}
-	if (schdlr_sspnd.msb.procs)
-	    res = ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED;
-	else {
-	    ERTS_SCHDLR_SSPND_CHNG_SET(ERTS_SCHDLR_SSPND_CHNG_MSB, 0);
-	    p->flags &= ~F_HAVE_BLCKD_MSCHED;
-	    schdlr_sspnd.msb.ongoing = 0;
-	    if (schdlr_sspnd.online == 1) {
+	if (!msbp->blckrs && !msbp->chngq) {
+	    int online = (int) schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,
+							ERTS_SCHED_NORMAL);
+	    erts_smp_atomic32_read_bor_nob(&schdlr_sspnd.changing,
+					   chng_flg);
+	    p->flags &= ~have_blckd_flg;
+	    msbp->ongoing = 0;
+	    if (online == 1) {
 		/* No normal schedulers to resume */
-		ASSERT(erts_smp_atomic32_read_nob(&schdlr_sspnd.active) == 1);
-		ERTS_SCHDLR_SSPND_CHNG_SET(0, ERTS_SCHDLR_SSPND_CHNG_MSB);
+		ASSERT(schdlr_sspnd_get_nscheds(&schdlr_sspnd.active,
+						ERTS_SCHED_NORMAL) == 1);
+#ifndef ERTS_DIRTY_SCHEDULERS
+		erts_smp_atomic32_read_band_nob(&schdlr_sspnd.changing,
+						~chng_flg);
+#endif
 	    }
-	    else {
-		online = schdlr_sspnd.online;
+	    else if (!(schdlr_sspnd.msb.ongoing|schdlr_sspnd.nmsb.ongoing)) {
 		if (plocks) {
 		    have_unlocked_plocks = 1;
 		    erts_smp_proc_unlock(p, plocks);
@@ -8031,83 +7911,91 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all)
 		    suspend_run_queue(ERTS_RUNQ_IX(ix));
 	    }
 #ifdef ERTS_DIRTY_SCHEDULERS
-	    ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET(ERTS_SCHDLR_SSPND_CHNG_MSB, 0);
-	    schdlr_sspnd.msb.dirty_cpu_wait_active = schdlr_sspnd.dirty_cpu_online;
-	    for (ix = 0; ix < schdlr_sspnd.dirty_cpu_online; ix++) {
-		ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
-		scheduler_ssi_resume_wake(ssi);
-		erts_smp_atomic32_read_band_nob(&ssi->flags,
-						~ERTS_SSI_FLG_SUSPENDED);
-	    }
-	    wake_dirty_schedulers(ERTS_DIRTY_CPU_RUNQ, 0);
-
-	    ERTS_SCHDLR_SSPND_DIRTY_IO_CHNG_SET(ERTS_SCHDLR_SSPND_CHNG_MSB, 0);
-	    schdlr_sspnd.msb.dirty_io_wait_active = erts_no_dirty_io_schedulers;
-	    for (ix = 0; ix < erts_no_dirty_io_schedulers; ix++) {
-		ssi = ERTS_DIRTY_IO_SCHED_SLEEP_INFO_IX(ix);
-		scheduler_ssi_resume_wake(ssi);
-		erts_smp_atomic32_read_band_nob(&ssi->flags,
-						~ERTS_SSI_FLG_SUSPENDED);
-	    }
-	    wake_dirty_schedulers(ERTS_DIRTY_IO_RUNQ, 0);
+	    if (!normal) {
+		ASSERT(!schdlr_sspnd.msb.ongoing);
+		online = (int) schdlr_sspnd_get_nscheds(&schdlr_sspnd.online,
+							ERTS_SCHED_DIRTY_CPU);
+		for (ix = 0; ix < online; ix++) {
+		    ssi = ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(ix);
+		    scheduler_ssi_resume_wake(ssi);
+		}
+
+		for (ix = 0; ix < erts_no_dirty_io_schedulers; ix++) {
+		    ssi = ERTS_DIRTY_IO_SCHED_SLEEP_INFO_IX(ix);
+		    scheduler_ssi_resume_wake(ssi);
+		}
+	    }
 #endif
-	    res = ERTS_SCHDLR_SSPND_DONE;
 	}
+
+    unblock_res:
+	if (schdlr_sspnd.msb.ongoing)
+	    res = ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED;
+	else if (schdlr_sspnd.nmsb.ongoing)
+	    res = ERTS_SCHDLR_SSPND_DONE_NMSCHED_BLOCKED;
+	else
+	    res = ERTS_SCHDLR_SSPND_DONE;
     }
 
     erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
+
     if (have_unlocked_plocks)
 	erts_smp_proc_lock(p, plocks);
-    return res;
-}
 
-#ifdef DEBUG
-void
-erts_dbg_multi_scheduling_return_trap(Process *p, Eterm return_value)
-{
-    if (return_value == am_blocked) {
-	erts_aint32_t active = erts_smp_atomic32_read_nob(&schdlr_sspnd.active);
-	ASSERT(1 <= active && active <= 2);
-	ASSERT(ERTS_PROC_GET_SCHDATA(p)->no == 1);
+    if (resume_proc) {
+	if (!(plocks & ERTS_PROC_LOCK_STATUS))
+	    erts_smp_proc_lock(p, ERTS_PROC_LOCK_STATUS);
+	resume_process(p, plocks|ERTS_PROC_LOCK_STATUS);
+	if (!(plocks & ERTS_PROC_LOCK_STATUS))
+	    erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
     }
+
+    return res;
 }
-#endif
 
 int
 erts_is_multi_scheduling_blocked(void)
 {
     int res;
     erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-    res = schdlr_sspnd.msb.procs != NULL;
+    if (schdlr_sspnd.msb.blckrs)
+	res = 1;
+    else if (schdlr_sspnd.nmsb.blckrs)
+	res = -1;
+    else
+	res = 0;
     erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
     return res;
 }
 
 Eterm
-erts_multi_scheduling_blockers(Process *p)
+erts_multi_scheduling_blockers(Process *p, int normal)
 {
     Eterm res = NIL;
+    ErtsMultiSchedulingBlock *msbp;
+
+    msbp = normal ? &schdlr_sspnd.nmsb : &schdlr_sspnd.msb;
 
     erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-    if (!erts_proclist_is_empty(schdlr_sspnd.msb.procs)) {
+    if (!erts_proclist_is_empty(msbp->blckrs)) {
 	Eterm *hp, *hp_end;
 	ErtsProcList *plp1, *plp2;
 	Uint max_size = 0;
 
-	for (plp1 = erts_proclist_peek_first(schdlr_sspnd.msb.procs);
+	for (plp1 = erts_proclist_peek_first(msbp->blckrs);
 	     plp1;
-	     plp1 = erts_proclist_peek_next(schdlr_sspnd.msb.procs, plp1)) {
+	     plp1 = erts_proclist_peek_next(msbp->blckrs, plp1)) {
 	    max_size += 2;
 	}
 	ASSERT(max_size);
 	hp = HAlloc(p, max_size);
 	hp_end = hp + max_size;
-	for (plp1 = erts_proclist_peek_first(schdlr_sspnd.msb.procs);
+	for (plp1 = erts_proclist_peek_first(msbp->blckrs);
 	     plp1;
-	     plp1 = erts_proclist_peek_next(schdlr_sspnd.msb.procs, plp1)) {
-	    for (plp2 = erts_proclist_peek_first(schdlr_sspnd.msb.procs);
+	     plp1 = erts_proclist_peek_next(msbp->blckrs, plp1)) {
+	    for (plp2 = erts_proclist_peek_first(msbp->blckrs);
 		 plp2->pid != plp1->pid;
-		 plp2 = erts_proclist_peek_next(schdlr_sspnd.msb.procs, plp2));
+		 plp2 = erts_proclist_peek_next(msbp->blckrs, plp2));
 	    if (plp2 == plp1) {
 		res = CONS(hp, plp1->pid, res);
 		hp += 2;
@@ -8176,39 +8064,6 @@ sched_thread_func(void *vesdp)
 #endif
     erts_thread_init_float();
 
-    if (no == 1) {
-	erts_thr_progress_active(esdp, 0);
-	erts_thr_progress_prepare_wait(esdp);
-    }
-
-    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-
-    ASSERT(erts_smp_atomic32_read_nob(&schdlr_sspnd.changing)
-	   & ERTS_SCHDLR_SSPND_CHNG_ONLN);
-
-    if (--schdlr_sspnd.curr_online == schdlr_sspnd.wait_curr_online) {
-	erts_smp_atomic32_read_band_nob(&schdlr_sspnd.changing,
-					~ERTS_SCHDLR_SSPND_CHNG_ONLN);
-	if (no != 1)
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    erts_smp_cnd_broadcast(&schdlr_sspnd.cnd);
-#else
-	    erts_smp_cnd_signal(&schdlr_sspnd.cnd);
-#endif
-    }
-
-    if (no == 1) {
-	while (schdlr_sspnd.curr_online != schdlr_sspnd.wait_curr_online)
-	    erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
-	ERTS_SCHDLR_SSPND_CHNG_SET(0, ERTS_SCHDLR_SSPND_CHNG_WAITER);
-    }
-    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-
-    if (no == 1) {
-	erts_thr_progress_finalize_wait(esdp);
-	erts_thr_progress_active(esdp, 1);
-    }
-
 #ifdef ERTS_DO_VERIFY_UNUSED_TEMP_ALLOC
     esdp->verify_unused_temp_alloc
 	= erts_alloc_get_verify_unused_temp_alloc(
@@ -8263,24 +8118,6 @@ sched_dirty_cpu_thread_func(void *vesdp)
 #endif
     erts_thread_init_float();
 
-    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-    ASSERT(erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_cpu_changing)
-	   & ERTS_SCHDLR_SSPND_CHNG_ONLN);
-
-    if (--schdlr_sspnd.dirty_cpu_curr_online == schdlr_sspnd.dirty_cpu_wait_curr_online) {
-	erts_smp_atomic32_read_band_nob(&schdlr_sspnd.dirty_cpu_changing,
-					~ERTS_SCHDLR_SSPND_CHNG_ONLN);
-	if (no != 1)
-	    erts_smp_cnd_broadcast(&schdlr_sspnd.cnd);
-    }
-
-    if (no == 1) {
-	while (schdlr_sspnd.dirty_cpu_curr_online != schdlr_sspnd.dirty_cpu_wait_curr_online)
-	    erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
-	ERTS_SCHDLR_SSPND_DIRTY_CPU_CHNG_SET(0, ERTS_SCHDLR_SSPND_CHNG_WAITER);
-    }
-    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-
     process_main();
     /* No schedulers should *ever* terminate */
     erts_exit(ERTS_ABORT_EXIT,
@@ -8326,24 +8163,6 @@ sched_dirty_io_thread_func(void *vesdp)
 #endif
     erts_thread_init_float();
 
-    erts_smp_mtx_lock(&schdlr_sspnd.mtx);
-    ASSERT(erts_smp_atomic32_read_nob(&schdlr_sspnd.dirty_io_changing)
-	   & ERTS_SCHDLR_SSPND_CHNG_ONLN);
-
-    if (--schdlr_sspnd.dirty_io_curr_online == schdlr_sspnd.dirty_io_wait_curr_online) {
-	erts_smp_atomic32_read_band_nob(&schdlr_sspnd.dirty_io_changing,
-					~ERTS_SCHDLR_SSPND_CHNG_ONLN);
-	if (no != 1)
-	    erts_smp_cnd_broadcast(&schdlr_sspnd.cnd);
-    }
-
-    if (no == 1) {
-	while (schdlr_sspnd.dirty_io_curr_online != schdlr_sspnd.dirty_io_wait_curr_online)
-	    erts_smp_cnd_wait(&schdlr_sspnd.cnd, &schdlr_sspnd.mtx);
-	ERTS_SCHDLR_SSPND_DIRTY_IO_CHNG_SET(0, ERTS_SCHDLR_SSPND_CHNG_WAITER);
-    }
-    erts_smp_mtx_unlock(&schdlr_sspnd.mtx);
-
     process_main();
     /* No schedulers should *ever* terminate */
     erts_exit(ERTS_ABORT_EXIT,
@@ -9616,11 +9435,11 @@ Process *schedule(Process *p, int calls)
 	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);
-	}
+		rq->procs.pending_exiters = NULL;
+		erts_smp_runq_unlock(rq);
+		handle_pending_exiters(pnd_xtrs);
+		erts_smp_runq_lock(rq);
+	    }
 
 	    if (rq->check_balance_reds <= 0)
 		check_balance(rq);
@@ -12537,14 +12356,39 @@ erts_continue_exit_process(Process *p)
 #endif
 
 #ifdef ERTS_SMP
+    if (p->flags & F_SCHDLR_ONLN_WAITQ)
+	abort_sched_onln_chng_waitq(p);
+
     if (p->flags & F_HAVE_BLCKD_MSCHED) {
 	ErtsSchedSuspendResult ssr;
-	ssr = erts_block_multi_scheduling(p, ERTS_PROC_LOCK_MAIN, 0, 1);
+	ssr = erts_block_multi_scheduling(p, ERTS_PROC_LOCK_MAIN, 0, 0, 1);
+	switch (ssr) {
+	case ERTS_SCHDLR_SSPND_YIELD_RESTART:
+	    goto yield;
+	case ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED:
+	case ERTS_SCHDLR_SSPND_DONE_NMSCHED_BLOCKED:
+	case ERTS_SCHDLR_SSPND_YIELD_DONE_MSCHED_BLOCKED:
+	case ERTS_SCHDLR_SSPND_YIELD_DONE_NMSCHED_BLOCKED:
+	case ERTS_SCHDLR_SSPND_DONE:
+	case ERTS_SCHDLR_SSPND_YIELD_DONE:
+	    p->flags &= ~F_HAVE_BLCKD_MSCHED;
+	    break;
+	case ERTS_SCHDLR_SSPND_EINVAL:
+	default:
+	    erts_exit(ERTS_ABORT_EXIT, "%s:%d: Internal error: %d\n",
+		      __FILE__, __LINE__, (int) ssr);
+	}
+    }
+    if (p->flags & F_HAVE_BLCKD_NMSCHED) {
+	ErtsSchedSuspendResult ssr;
+	ssr = erts_block_multi_scheduling(p, ERTS_PROC_LOCK_MAIN, 0, 1, 1);
 	switch (ssr) {
 	case ERTS_SCHDLR_SSPND_YIELD_RESTART:
 	    goto yield;
 	case ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED:
+	case ERTS_SCHDLR_SSPND_DONE_NMSCHED_BLOCKED:
 	case ERTS_SCHDLR_SSPND_YIELD_DONE_MSCHED_BLOCKED:
+	case ERTS_SCHDLR_SSPND_YIELD_DONE_NMSCHED_BLOCKED:
 	case ERTS_SCHDLR_SSPND_DONE:
 	case ERTS_SCHDLR_SSPND_YIELD_DONE:
 	    p->flags &= ~F_HAVE_BLCKD_MSCHED;
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index 6b370e630e..c88bd7056c 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -79,10 +79,8 @@ struct ErtsNodesMonitor_;
 #define ERTS_HAVE_SCHED_UTIL_BALANCING_SUPPORT		0
 
 #define ERTS_MAX_NO_OF_SCHEDULERS 1024
-#ifdef ERTS_DIRTY_SCHEDULERS
 #define ERTS_MAX_NO_OF_DIRTY_CPU_SCHEDULERS ERTS_MAX_NO_OF_SCHEDULERS
 #define ERTS_MAX_NO_OF_DIRTY_IO_SCHEDULERS ERTS_MAX_NO_OF_SCHEDULERS
-#endif
 
 #define ERTS_DEFAULT_MAX_PROCESSES (1 << 18)
 
@@ -246,7 +244,9 @@ extern int erts_sched_thread_suggested_stack_size;
 
 typedef enum {
     ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED,
+    ERTS_SCHDLR_SSPND_DONE_NMSCHED_BLOCKED,
     ERTS_SCHDLR_SSPND_YIELD_DONE_MSCHED_BLOCKED,
+    ERTS_SCHDLR_SSPND_YIELD_DONE_NMSCHED_BLOCKED,
     ERTS_SCHDLR_SSPND_DONE,
     ERTS_SCHDLR_SSPND_YIELD_RESTART,
     ERTS_SCHDLR_SSPND_YIELD_DONE,
@@ -1339,6 +1339,8 @@ extern int erts_system_profile_ts_type;
 #define F_OFF_HEAP_MSGQ_CHNG (1 << 14) /* Off heap msg queue changing */
 #define F_ABANDONED_HEAP_USE (1 << 15) /* Have usage of abandoned heap */
 #define F_DELAY_GC           (1 << 16) /* Similar to disable GC (see below) */
+#define F_SCHDLR_ONLN_WAITQ  (1 << 17) /* Process enqueued waiting to change schedulers online */
+#define F_HAVE_BLCKD_NMSCHED (1 << 18) /* Process has blocked normal multi-scheduling */
 
 /*
  * F_DISABLE_GC and F_DELAY_GC are similar. Both will prevent
@@ -1533,6 +1535,7 @@ int erts_setup_nif_gc(Process* proc, Eterm** objv, int* nobj); /* see erl_nif.c
 void erts_destroy_nif_export(void *); /* see erl_nif.c */
 
 ErtsProcList *erts_proclist_create(Process *);
+ErtsProcList *erts_proclist_copy(ErtsProcList *);
 void erts_proclist_destroy(ErtsProcList *);
 
 ERTS_GLB_INLINE int erts_proclist_same(ErtsProcList *, Process *);
@@ -1718,28 +1721,21 @@ void erts_schedule_complete_off_heap_message_queue_change(Eterm pid);
 #if defined(ERTS_SMP) && defined(ERTS_ENABLE_LOCK_CHECK)
 int erts_dbg_check_halloc_lock(Process *p);
 #endif
-#ifdef DEBUG
-void erts_dbg_multi_scheduling_return_trap(Process *, Eterm);
-#endif
-int erts_get_max_no_executing_schedulers(void);
 #if defined(ERTS_SMP) || defined(ERTS_DIRTY_SCHEDULERS)
-ErtsSchedSuspendResult
-erts_schedulers_state(Uint *, Uint *, Uint *, Uint *, Uint *, Uint *, int);
+void
+erts_schedulers_state(Uint *, Uint *, Uint *, Uint *, Uint *, Uint *, Uint *, Uint *);
 #endif
 #ifdef ERTS_SMP
 ErtsSchedSuspendResult
 erts_set_schedulers_online(Process *p,
 			   ErtsProcLocks plocks,
 			   Sint new_no,
-			   Sint *old_no
-#ifdef ERTS_DIRTY_SCHEDULERS
-			   , int dirty_only
-#endif
-			   );
+			   Sint *old_no,
+			   int dirty_only);
 ErtsSchedSuspendResult
-erts_block_multi_scheduling(Process *, ErtsProcLocks, int, int);
+erts_block_multi_scheduling(Process *, ErtsProcLocks, int, int, int);
 int erts_is_multi_scheduling_blocked(void);
-Eterm erts_multi_scheduling_blockers(Process *);
+Eterm erts_multi_scheduling_blockers(Process *, int);
 void erts_start_schedulers(void);
 void erts_alloc_notify_delayed_dealloc(int);
 void erts_alloc_ensure_handle_delayed_dealloc_call(int);