Improved scheduler suspend functionality

- The calling process is now suspended while synchronizing
  scheduler suspends via erlang:system_flag(schedulers_online, _)
  and erlang:system_flag(multi_scheduling, _), instead of blocking
  the scheduler thread in the BIF call waiting for the operation
  to synchronize. Besides releasing the scheduler for other work
  (or immediate suspend) it also makes it possible to abort the
  operation by killing the process.
- erlang:system_flag(schedulers_online, _) now only wait for normal
  schedulers to complete before it returns. This since it may take
  a very long time before all dirty schedulers suspends.
- erlang:system_flag(multi_scheduling, block_normal|unblock_normal)
  which only operate on normal schedulers has been introduced. This
  since there are use cases where suspend of dirty schedulers are
  not of interest (hipe loader).
- erlang:system_flag(multi_scheduling, block) still blocks all
  dirty schedulers as well as all normal schedulers except one since
  it is hard to redefine what multi scheduling block means.
- The three operations:
  - changing amount of schedulers online
  - blocking/unblocking normal multi scheduling
  - blocking/unblocking full multi scheduling
  can now be done in parallel. This is important since otherwise
  a full multi scheduling block would potentially delay the other
  operations for a very long time.

1 files changed, 979 insertions, 1135 deletions

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;