4 files changed, 458 insertions, 265 deletions

diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index d7a2076d85..962cb4858f 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -1772,12 +1772,10 @@ execute_dirty_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
     ep = (NifExport*) ERTS_PROC_GET_NIF_TRAP_EXPORT(proc);
     ASSERT(ep);
     ep->fp = NULL;
+    erts_smp_atomic32_read_band_mb(&proc->state, ~(ERTS_PSFLG_DIRTY_CPU_PROC
+						   | ERTS_PSFLG_DIRTY_IO_PROC));
     result = (*fp)(env, argc, argv);
-    erts_smp_atomic32_read_band_mb(&proc->state,
-				   ~(ERTS_PSFLG_DIRTY_CPU_PROC
-				     |ERTS_PSFLG_DIRTY_IO_PROC
-				     |ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q
-				     |ERTS_PSFLG_DIRTY_IO_PROC_IN_Q));
+
     if (erts_refc_dectest(&env->mod_nif->rt_dtor_cnt, 0) == 0 && env->mod_nif->mod == NULL)
 	close_lib(env->mod_nif);
     /*
@@ -1825,13 +1823,6 @@ schedule_dirty_nif(ErlNifEnv* env, int flags, int argc, const ERL_NIF_TERM argv[
     a = erts_smp_atomic32_read_acqb(&proc->state);
     while (1) {
 	n = state = a;
-	/*
-	 * clear any current dirty flags and dirty queue indicators,
-	 * in case the application is shifting a job from one type
-	 * of dirty scheduler to the other
-	 */
-	n &= ~(ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC
-	       |ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q|ERTS_PSFLG_DIRTY_IO_PROC_IN_Q);
 	if (flags == ERL_NIF_DIRTY_JOB_CPU_BOUND)
 	    n |= ERTS_PSFLG_DIRTY_CPU_PROC;
 	else
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index d583118e7b..1765315ed3 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -2969,7 +2969,7 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 	    sched_wall_time_change(esdp, thr_prgr_active);
 
 	while (1) {
-	    ErtsMonotonicTime current_time;
+	    ErtsMonotonicTime current_time = 0;
 
 	    aux_work = erts_atomic32_read_acqb(&ssi->aux_work);
 	    if (aux_work) {
@@ -3635,6 +3635,13 @@ check_requeue_process(ErtsRunQueue *rq, int prio_q)
     return 0;
 }
 
+static ERTS_INLINE void
+free_proxy_proc(Process *proxy)
+{
+    ASSERT(erts_smp_atomic32_read_nob(&proxy->state) & ERTS_PSFLG_PROXY);
+    erts_free(ERTS_ALC_T_PROC, proxy);
+}
+
 #ifdef ERTS_SMP
 
 static ErtsRunQueue *
@@ -3949,9 +3956,6 @@ evacuate_run_queue(ErtsRunQueue *rq,
 	erts_aint32_t state;
 	Process *proc;
 	int notify = 0;
-#ifdef ERTS_DIRTY_SCHEDULERS
-	int requeue;
-#endif
 	to_rq = NULL;
 
 #ifdef ERTS_DIRTY_SCHEDULERS
@@ -3966,49 +3970,94 @@ evacuate_run_queue(ErtsRunQueue *rq,
 
 	proc = dequeue_process(rq, prio_q, &state);
 	while (proc) {
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    requeue = 1;
+	    Process *real_proc;
+	    int prio;
+	    erts_aint32_t max_qbit, qbit, real_state;
+
+	    prio = ERTS_PSFLGS_GET_PRQ_PRIO(state);
+	    qbit = ((erts_aint32_t) 1) << prio;
+
+	    if (!(state & ERTS_PSFLG_PROXY)) {
+		real_proc = proc;
+		real_state = state;
+	    }
+	    else {
+		real_proc = erts_proc_lookup_raw(proc->common.id);
+		if (!real_proc) {
+		    free_proxy_proc(proc);
+		    goto handle_next_proc;
+		}
+		real_state =  erts_smp_atomic32_read_acqb(&real_proc->state);
+	    }
+
+	    max_qbit = (state >> ERTS_PSFLGS_IN_PRQ_MASK_OFFSET);
+	    max_qbit &= ERTS_PSFLGS_QMASK;
+	    max_qbit |= 1 << ERTS_PSFLGS_QMASK_BITS;
+	    max_qbit &= -max_qbit;
+
+	    if (qbit > max_qbit) {
+		/* Process already queued with higher prio; drop it... */
+		if (real_proc != proc)
+		    free_proxy_proc(proc);
+		else {
+		    erts_aint32_t clr_bits;
+#ifdef DEBUG
+		    erts_aint32_t old;
 #endif
-	    if (ERTS_PSFLG_BOUND & state) {
-		/* Bound processes get stuck here... */
-		proc->next = NULL;
-		if (sbpp->last)
-		    sbpp->last->next = proc;
-		else
-		    sbpp->first = proc;
-		sbpp->last = proc;
-#ifdef ERTS_DIRTY_SCHEDULERS
-		requeue = 0;
+
+		    clr_bits = ERTS_PSFLG_IN_RUNQ;
+		    clr_bits |= qbit << ERTS_PSFLGS_IN_PRQ_MASK_OFFSET;
+
+#ifdef DEBUG
+		    old =
+#else
+			(void)
 #endif
+			erts_smp_atomic32_read_band_mb(&proc->state,
+						       ~clr_bits);
+			ASSERT((old & clr_bits) == clr_bits);
+
+		}
+
+		goto handle_next_proc;
 	    }
+
 #ifdef ERTS_DIRTY_SCHEDULERS
-	    else if (state & ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q) {
+
+	    if (ERTS_RUNQ_IX_IS_DIRTY(rq->ix)) {
+		erts_aint32_t dqbit = qbit;
 #ifdef DEBUG
-		erts_aint32_t old =
-#else
-		(void)
+		erts_aint32_t old_dqbit;
 #endif
-		    erts_smp_atomic32_read_band_nob(&proc->state,
-						    ~(ERTS_PSFLG_DIRTY_CPU_PROC
-						      | ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q));
-		/* assert that no other dirty flags are set */
-		ASSERT(!(old & (ERTS_PSFLG_DIRTY_IO_PROC|ERTS_PSFLG_DIRTY_IO_PROC_IN_Q)));
-	    } else if (state & ERTS_PSFLG_DIRTY_IO_PROC_IN_Q) {
+
+		if (rq == ERTS_DIRTY_CPU_RUNQ)
+		    dqbit <<= ERTS_PDSFLGS_IN_CPU_PRQ_MASK_OFFSET;
+		else {
+		    ASSERT(rq == ERTS_DIRTY_IO_RUNQ);
+		    dqbit <<= ERTS_PDSFLGS_IN_IO_PRQ_MASK_OFFSET;
+		}
+
 #ifdef DEBUG
-		erts_aint32_t old =
+		old_dqbit = (int)
 #else
-		(void)
+		    (void)
 #endif
-		    erts_smp_atomic32_read_band_nob(&proc->state,
-						    ~(ERTS_PSFLG_DIRTY_IO_PROC
-						      | ERTS_PSFLG_DIRTY_IO_PROC_IN_Q));
-		/* assert that no other dirty flags are set */
-		ASSERT(!(old & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q)));
+		    erts_smp_atomic32_read_band_mb(&real_proc->dirty_state,
+						   ~dqbit);
+		ASSERT(old_dqbit & dqbit);
 	    }
-	    if (requeue) {
-#else
-	    else {
 #endif
+
+	    if (ERTS_PSFLG_BOUND & real_state) {
+		/* Bound processes get stuck here... */
+		proc->next = NULL;
+		if (sbpp->last)
+		    sbpp->last->next = proc;
+		else
+		    sbpp->first = proc;
+		sbpp->last = proc;
+	    }
+	    else {
 		int prio = (int) ERTS_PSFLGS_GET_PRQ_PRIO(state);
 		erts_smp_runq_unlock(rq);
 
@@ -4031,6 +4080,8 @@ evacuate_run_queue(ErtsRunQueue *rq,
 
 		erts_smp_runq_lock(rq);
 	    }
+
+	handle_next_proc:
 	    proc = dequeue_process(rq, prio_q, &state);
 	}
 	if (notify)
@@ -5974,19 +6025,96 @@ make_proxy_proc(Process *prev_proxy, Process *proc, erts_aint32_t prio)
     return proxy;
 }
 
-static ERTS_INLINE void
-free_proxy_proc(Process *proxy)
-{
-    ASSERT(erts_smp_atomic32_read_nob(&proxy->state) & ERTS_PSFLG_PROXY);
-    erts_free(ERTS_ALC_T_PROC, proxy);
-}
-
 #define ERTS_ENQUEUE_NOT 0
 #define ERTS_ENQUEUE_NORMAL_QUEUE 1
-#ifdef ERTS_DIRTY_SCHEDULERS
 #define ERTS_ENQUEUE_DIRTY_CPU_QUEUE 2
 #define ERTS_ENQUEUE_DIRTY_IO_QUEUE 3
+
+#ifdef ERTS_DIRTY_SCHEDULERS
+
+static int
+check_dirty_enqueue_in_prio_queue(Process *c_p,
+				  erts_aint32_t *newp,
+				  erts_aint32_t actual,
+				  erts_aint32_t aprio,
+				  erts_aint32_t qbit)
+{
+    int queue;
+    erts_aint32_t dact, max_qbit;
+
+    /* Termination should be done on an ordinary scheduler */
+    if (actual & ERTS_PSFLG_EXITING) {
+	*newp &= ~ERTS_PSFLGS_DIRTY_WORK;
+	return ERTS_ENQUEUE_NORMAL_QUEUE;
+    }
+
+    /*
+     * If we have system tasks, we enqueue on ordinary run-queue
+     * and take care of those system tasks first.
+     */
+    if (actual & ERTS_PSFLG_ACTIVE_SYS)
+	return ERTS_ENQUEUE_NORMAL_QUEUE;
+
+    dact = erts_smp_atomic32_read_mb(&c_p->dirty_state);
+    if (actual & (ERTS_PSFLG_DIRTY_ACTIVE_SYS
+		  | ERTS_PSFLG_DIRTY_CPU_PROC)) {
+	max_qbit = ((dact >> ERTS_PDSFLGS_IN_CPU_PRQ_MASK_OFFSET)
+		    & ERTS_PDSFLGS_QMASK);
+	queue = ERTS_ENQUEUE_DIRTY_CPU_QUEUE;
+    }
+    else {
+	ASSERT(actual & ERTS_PSFLG_DIRTY_IO_PROC);
+	max_qbit = ((dact >> ERTS_PDSFLGS_IN_IO_PRQ_MASK_OFFSET)
+		    & ERTS_PDSFLGS_QMASK);
+	queue = ERTS_ENQUEUE_DIRTY_IO_QUEUE;
+    }
+
+    max_qbit |= 1 << ERTS_PSFLGS_QMASK_BITS;
+    max_qbit &= -max_qbit;
+
+    if (qbit >= max_qbit)
+	return ERTS_ENQUEUE_NOT; /* Already queued in higher or equal prio */
+    if ((actual & (ERTS_PSFLG_IN_RUNQ|ERTS_PSFLGS_USR_PRIO_MASK))
+	!= (aprio << ERTS_PSFLGS_USR_PRIO_OFFSET)) {
+	/*
+	 * Process struct already enqueued, or actual prio not
+	 * equal to user prio, i.e., enqueue using proxy.
+	 */
+	return -1*queue;
+    }
+
+    *newp |= ERTS_PSFLG_IN_RUNQ;
+    return queue;
+}
+
+static ERTS_INLINE int
+fin_dirty_enq_s_change(Process *p,
+		       int pstruct_reserved,
+		       erts_aint32_t enq_prio,
+		       int qmask_offset)
+{
+    erts_aint32_t qbit = 1 << enq_prio;
+    qbit <<= qmask_offset;
+
+    if (qbit & erts_smp_atomic32_read_bor_mb(&p->dirty_state, qbit)) {
+	/* Already enqueue by someone else... */
+	if (pstruct_reserved) {
+	    /* We reserved process struct for enqueue; clear it... */
+#ifdef DEBUG
+	    erts_aint32_t old =
+#else
+		(void)
 #endif
+		erts_smp_atomic32_read_band_nob(&p->state, ~ERTS_PSFLG_IN_RUNQ);
+	    ASSERT(old & ERTS_PSFLG_IN_RUNQ);
+	}
+	return 0;
+    }
+
+    return !0;
+}
+
+#endif /* ERTS_DIRTY_SCHEDULERS */
 
 static ERTS_INLINE int
 check_enqueue_in_prio_queue(Process *c_p,
@@ -6002,61 +6130,14 @@ check_enqueue_in_prio_queue(Process *c_p,
     *prq_prio_p = aprio;
 
 #ifdef ERTS_DIRTY_SCHEDULERS
-    if (actual & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC)) {
-        /*
-         * If we have system tasks of a priority higher
-         * or equal to the user priority, we enqueue
-         * on ordinary run-queue and take care of
-         * those system tasks first.
-         */
-        if (actual & ERTS_PSFLG_ACTIVE_SYS) {
-            erts_aint32_t uprio, stprio, qmask;
-            uprio = (actual >> ERTS_PSFLGS_USR_PRIO_OFFSET) & ERTS_PSFLGS_PRIO_MASK;
-            if (aprio < uprio)
-                goto enqueue_normal_runq; /* system tasks with higher prio */
-            erts_smp_proc_lock(c_p, ERTS_PROC_LOCK_STATUS);
-            qmask = c_p->sys_task_qs->qmask;
-            erts_smp_proc_unlock(c_p, ERTS_PROC_LOCK_STATUS);
-            switch (qmask & -qmask) {
-            case MAX_BIT:
-                stprio = PRIORITY_MAX;
-                break;
-            case HIGH_BIT:
-                stprio = PRIORITY_HIGH;
-                break;
-            case NORMAL_BIT:
-                stprio = PRIORITY_NORMAL;
-                break;
-            case LOW_BIT:
-                stprio = PRIORITY_LOW;
-                break;
-            default:
-                stprio = PRIORITY_LOW+1;
-                break;
-            }
-            if (stprio <= uprio)
-                goto enqueue_normal_runq; /* system tasks with higher prio */
-        }
-
-        /* Enqueue in dirty run queue if not already enqueued */
-	if (actual & (ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q|ERTS_PSFLG_DIRTY_IO_PROC_IN_Q))
-	    return ERTS_ENQUEUE_NOT; /* already in queue */
-        if (actual & ERTS_PSFLG_DIRTY_CPU_PROC) {
-	    *newp |= ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q;
-            if (actual & ERTS_PSFLG_IN_RUNQ)
-                return -ERTS_ENQUEUE_DIRTY_CPU_QUEUE; /* use proxy */
-	    *newp |= ERTS_PSFLG_IN_RUNQ;
-            return ERTS_ENQUEUE_DIRTY_CPU_QUEUE;
-        }
-	*newp |= ERTS_PSFLG_DIRTY_IO_PROC_IN_Q;
-        if (actual & ERTS_PSFLG_IN_RUNQ)
-            return -ERTS_ENQUEUE_DIRTY_IO_QUEUE; /* use proxy */
-	*newp |= ERTS_PSFLG_IN_RUNQ;
-        return ERTS_ENQUEUE_DIRTY_IO_QUEUE;
+    if (actual & ERTS_PSFLGS_DIRTY_WORK) {
+	int res = check_dirty_enqueue_in_prio_queue(c_p, newp, actual,
+						    aprio, qbit);
+	if (res != ERTS_ENQUEUE_NORMAL_QUEUE)
+	    return res;
     }
-
- enqueue_normal_runq:
 #endif
+
     max_qbit = (actual >> ERTS_PSFLGS_IN_PRQ_MASK_OFFSET) & ERTS_PSFLGS_QMASK;
     max_qbit |= 1 << ERTS_PSFLGS_QMASK_BITS;
     max_qbit &= -max_qbit;
@@ -6088,6 +6169,65 @@ check_enqueue_in_prio_queue(Process *c_p,
     return ERTS_ENQUEUE_NORMAL_QUEUE;
 }
 
+static ERTS_INLINE ErtsRunQueue *
+select_enqueue_run_queue(int enqueue, int enq_prio, Process *p, erts_aint32_t state)
+{
+
+    switch (enqueue) {
+
+    case ERTS_ENQUEUE_NOT:
+
+	return NULL;
+
+#ifdef ERTS_DIRTY_SCHEDULERS
+
+    case ERTS_ENQUEUE_DIRTY_CPU_QUEUE:
+    case -ERTS_ENQUEUE_DIRTY_CPU_QUEUE:
+
+	if (fin_dirty_enq_s_change(p, enqueue > 0, enq_prio,
+				   ERTS_PDSFLGS_IN_CPU_PRQ_MASK_OFFSET))
+	    return ERTS_DIRTY_CPU_RUNQ;
+
+	return NULL;
+
+
+    case ERTS_ENQUEUE_DIRTY_IO_QUEUE:
+    case -ERTS_ENQUEUE_DIRTY_IO_QUEUE:
+
+	if (fin_dirty_enq_s_change(p, enqueue > 0, enq_prio,
+				   ERTS_PDSFLGS_IN_IO_PRQ_MASK_OFFSET))
+	    return ERTS_DIRTY_IO_RUNQ;
+
+	return NULL;
+
+#endif
+
+    default: {
+	ErtsRunQueue* runq;
+
+	ASSERT(enqueue == ERTS_ENQUEUE_NORMAL_QUEUE
+	       || enqueue == -ERTS_ENQUEUE_NORMAL_QUEUE);
+
+	runq = erts_get_runq_proc(p);
+
+#ifdef ERTS_SMP
+	if (!(ERTS_PSFLG_BOUND & state)) {
+	    ErtsRunQueue *new_runq = erts_check_emigration_need(runq, enq_prio);
+	    if (new_runq) {
+		RUNQ_SET_RQ(&p->run_queue, new_runq);
+		runq = new_runq;
+	    }
+	}
+#endif
+
+	ASSERT(runq);
+
+	return runq;
+    }
+    }
+}
+
+
 /*
  * schedule_out_process() return with c_rq locked.
  */
@@ -6096,11 +6236,7 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p, Proces
 {
     erts_aint32_t a, e, n, enq_prio = -1;
     int enqueue; /* < 0 -> use proxy */
-    Process* sched_p;
     ErtsRunQueue* runq;
-#ifdef ERTS_SMP
-    int check_emigration_need;
-#endif
 
     a = state;
 
@@ -6112,7 +6248,7 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p, Proces
 	enqueue = ERTS_ENQUEUE_NOT;
 
 	n &= ~(ERTS_PSFLG_RUNNING|ERTS_PSFLG_RUNNING_SYS);
-	if (a & ERTS_PSFLG_ACTIVE_SYS
+	if (a & (ERTS_PSFLG_ACTIVE_SYS|ERTS_PSFLG_DIRTY_ACTIVE_SYS)
 	    || (a & (ERTS_PSFLG_ACTIVE|ERTS_PSFLG_SUSPENDED)) == ERTS_PSFLG_ACTIVE) {
 	    enqueue = check_enqueue_in_prio_queue(p, &enq_prio, &n, a);
 	}
@@ -6121,16 +6257,17 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p, Proces
 	    break;
     }
 
-    switch (enqueue) {
-    case ERTS_ENQUEUE_NOT:
+    runq = select_enqueue_run_queue(enqueue, enq_prio, p, n);
+
+    if (!runq) {
+
 	if (erts_system_profile_flags.runnable_procs) {
 
 	    /* Status lock prevents out of order "runnable proc" trace msgs */
 	    ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_STATUS & erts_proc_lc_my_proc_locks(p));
 
-	    if (!(a & ERTS_PSFLG_ACTIVE_SYS)
-		&& (!(a & ERTS_PSFLG_ACTIVE)
-		    || (a & ERTS_PSFLG_SUSPENDED))) {
+	    if (!(a & (ERTS_PSFLG_ACTIVE_SYS|ERTS_PSFLG_DIRTY_ACTIVE_SYS))
+		&& (!(a & ERTS_PSFLG_ACTIVE) || (a & ERTS_PSFLG_SUSPENDED))) {
 		/* Process inactive */
 		profile_runnable_proc(p, am_inactive);
 	    }
@@ -6143,98 +6280,76 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p, Proces
 
 	return 0;
 
-#ifdef ERTS_DIRTY_SCHEDULERS
-#ifdef ERTS_SMP
-    case ERTS_ENQUEUE_DIRTY_CPU_QUEUE:
-    case -ERTS_ENQUEUE_DIRTY_CPU_QUEUE:
-	runq = ERTS_DIRTY_CPU_RUNQ;
-	ASSERT(ERTS_SCHEDULER_IS_DIRTY_CPU(runq->scheduler));
-#ifdef ERTS_SMP
-	check_emigration_need = 0;
-#endif
-	break;
+    }
+    else {
+	Process* sched_p;
 
-    case ERTS_ENQUEUE_DIRTY_IO_QUEUE:
-    case -ERTS_ENQUEUE_DIRTY_IO_QUEUE:
-	runq = ERTS_DIRTY_IO_RUNQ;
-	ASSERT(ERTS_SCHEDULER_IS_DIRTY_IO(runq->scheduler));
-#ifdef ERTS_SMP
-	check_emigration_need = 0;
-#endif
-	break;
-#endif
-#endif
+	ASSERT(!(n & ERTS_PSFLG_SUSPENDED) || (n & (ERTS_PSFLG_ACTIVE_SYS
+						    | ERTS_PSFLG_DIRTY_ACTIVE_SYS)));
 
-    default:
-	ASSERT(enqueue == ERTS_ENQUEUE_NORMAL_QUEUE
-	       || enqueue == -ERTS_ENQUEUE_NORMAL_QUEUE);
+	if (enqueue < 0)
+	    sched_p = make_proxy_proc(proxy, p, enq_prio);
+	else {
+	    sched_p = p;
+	    if (proxy)
+		free_proxy_proc(proxy);
+	}
 
-	runq = erts_get_runq_proc(p);
-#ifdef ERTS_SMP
-	check_emigration_need = !(ERTS_PSFLG_BOUND & n);
-#endif
-	break;
-    }
+	ASSERT(runq);
 
-    ASSERT(!(n & ERTS_PSFLG_SUSPENDED) || (n & ERTS_PSFLG_ACTIVE_SYS));
+	erts_smp_runq_lock(runq);
 
-    if (enqueue < 0)
-	sched_p = make_proxy_proc(proxy, p, enq_prio);
-    else {
-	sched_p = p;
-	if (proxy)
-	    free_proxy_proc(proxy);
-    }
+	/* Enqueue the process */
+	enqueue_process(runq, (int) enq_prio, sched_p);
 
-#ifdef ERTS_SMP
-    if (check_emigration_need) {
-	ErtsRunQueue *new_runq = erts_check_emigration_need(runq, enq_prio);
-	if (new_runq) {
-	    RUNQ_SET_RQ(&sched_p->run_queue, new_runq);
-	    runq = new_runq;
-	}
-    }
-#endif
+	if (runq == c_rq)
+	    return 1;
 
-    ASSERT(runq);
+	erts_smp_runq_unlock(runq);
 
-    erts_smp_runq_lock(runq);
+	smp_notify_inc_runq(runq);
 
-    /* Enqueue the process */
-    enqueue_process(runq, (int) enq_prio, sched_p);
+	erts_smp_runq_lock(c_rq);
 
-    if (runq == c_rq)
 	return 1;
-    erts_smp_runq_unlock(runq);
-    smp_notify_inc_runq(runq);
-    erts_smp_runq_lock(c_rq);
-    return 1;
+    }
+
 }
 
 static ERTS_INLINE void
-add2runq(Process *p, erts_aint32_t state, erts_aint32_t prio)
+add2runq(int enqueue, erts_aint32_t prio,
+	 Process *proc, erts_aint32_t state,
+	 Process **proxy)
 {
-    ErtsRunQueue *runq = erts_get_runq_proc(p);
+    ErtsRunQueue *runq;
 
-#ifdef ERTS_SMP
-    if (!(ERTS_PSFLG_BOUND & state)) {
-	ErtsRunQueue *new_runq = erts_check_emigration_need(runq, (int) prio);
-	if (new_runq) {
-	    RUNQ_SET_RQ(&p->run_queue, new_runq);
-	    runq = new_runq;
-	}
-    }
-#endif
-    ASSERT(runq);
+    runq = select_enqueue_run_queue(enqueue, prio, proc, state);
 
-    erts_smp_runq_lock(runq);
+    if (runq) {
+	Process *sched_p;
 
-    /* Enqueue the process */
-    enqueue_process(runq, (int) prio, p);
+	if (enqueue > 0)
+	    sched_p = proc;
+	else {
+	    Process *pxy;
 
-    erts_smp_runq_unlock(runq);
-    smp_notify_inc_runq(runq);
+	    if (!proxy)
+		pxy = NULL;
+	    else {
+		pxy = *proxy;
+		*proxy = NULL;
+	    }
+	    sched_p = make_proxy_proc(pxy, proc, prio);
+	}
+
+	erts_smp_runq_lock(runq);
+
+	/* Enqueue the process */
+	enqueue_process(runq, (int) prio, sched_p);
 
+	erts_smp_runq_unlock(runq);
+	smp_notify_inc_runq(runq);
+    }
 }
 
 static ERTS_INLINE int
@@ -6340,10 +6455,7 @@ schedule_process(Process *p, erts_aint32_t in_state, ErtsProcLocks locks)
 					     &state,
 					     &enq_prio,
 					     locks);
-    if (enqueue != ERTS_ENQUEUE_NOT)
-	add2runq(enqueue > 0 ? p : make_proxy_proc(NULL, p, enq_prio),
-		 state,
-		 enq_prio);
+    add2runq(enqueue, enq_prio, p, state, NULL);
 }
 
 void
@@ -6403,16 +6515,7 @@ schedule_process_sys_task(Process *p, erts_aint32_t state, Process *proxy)
 	prof_runnable_procs = 0;
     }
 
-    if (enqueue != ERTS_ENQUEUE_NOT) {
-	Process *sched_p;
-	if (enqueue > 0)
-	    sched_p = p;
-	else {
-	    sched_p = make_proxy_proc(proxy, p, enq_prio);
-	    proxy = NULL;
-	}
-	add2runq(sched_p, n, enq_prio);
-    }
+    add2runq(enqueue, enq_prio, p, n, &proxy);
 
 cleanup:
 
@@ -6508,10 +6611,7 @@ resume_process(Process *p, ErtsProcLocks locks)
 					 &state,
 					 &enq_prio,
 					 locks);
-    if (enqueue)
-	add2runq(enqueue > 0 ? p : make_proxy_proc(NULL, p, enq_prio),
-		 state,
-		 enq_prio);
+    add2runq(enqueue, enq_prio, p, state, NULL);
 }
 
 int
@@ -9361,15 +9461,16 @@ Process *schedule(Process *p, int calls)
 #ifdef ERTS_SMP
 	ErtsMigrationPaths *mps;
 	ErtsMigrationPath *mp;
-	ErtsProcList *pnd_xtrs = rq->procs.pending_exiters;
-	if (erts_proclist_fetch(&pnd_xtrs, NULL)) {
+
+	if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+	    ErtsProcList *pnd_xtrs = rq->procs.pending_exiters;
+	    if (erts_proclist_fetch(&pnd_xtrs, NULL)) {
 	    rq->procs.pending_exiters = NULL;
 	    erts_smp_runq_unlock(rq);
 	    handle_pending_exiters(pnd_xtrs);
 	    erts_smp_runq_lock(rq);
 	}
 
-	if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
 	    if (rq->check_balance_reds <= 0)
 		check_balance(rq);
 
@@ -9564,11 +9665,12 @@ Process *schedule(Process *p, int calls)
     pick_next_process: {
 	    erts_aint32_t psflg_band_mask;
 	    int prio_q;
-	    int qmask;
+	    int qmask, qbit;
 
 	    flags = ERTS_RUNQ_FLGS_GET_NOB(rq);
 	    qmask = (int) (flags & ERTS_RUNQ_FLGS_PROCS_QMASK);
-	    switch (qmask & -qmask) {
+	    qbit = qmask & -qmask;
+	    switch (qbit) {
 	    case MAX_BIT:
 		prio_q = PRIORITY_MAX;
 		break;
@@ -9596,20 +9698,11 @@ Process *schedule(Process *p, int calls)
 
 	    ASSERT(p); /* Wrong qmask in rq->flags? */
 
-	    psflg_band_mask = ~(((erts_aint32_t) 1) << (ERTS_PSFLGS_GET_PRQ_PRIO(state)
-							+ ERTS_PSFLGS_IN_PRQ_MASK_OFFSET));
-
-#ifdef ERTS_DIRTY_SCHEDULERS
-	    ASSERT((state & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC)) !=
-		   (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC));
-	    if (state & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC)) {
-		ASSERT((ERTS_SCHEDULER_IS_DIRTY_CPU(esdp) && (state & ERTS_PSFLG_DIRTY_CPU_PROC)) ||
-		       (ERTS_SCHEDULER_IS_DIRTY_IO(esdp) && (state & ERTS_PSFLG_DIRTY_IO_PROC)));
-		if (!ERTS_SCHEDULER_IS_DIRTY(esdp) && !(state & ERTS_PSFLG_ACTIVE_SYS))
-		    goto pick_next_process;
-		state &= ~(ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q|ERTS_PSFLG_DIRTY_IO_PROC_IN_Q);
-	    }
-#endif
+	    if (ERTS_SCHEDULER_IS_DIRTY(esdp))
+		psflg_band_mask = ~((erts_aint32_t) 0);
+	    else
+		psflg_band_mask = ~(((erts_aint32_t) 1) << (ERTS_PSFLGS_GET_PRQ_PRIO(state)
+							    + ERTS_PSFLGS_IN_PRQ_MASK_OFFSET));
 
 	    if (!(state & ERTS_PSFLG_PROXY))
 		psflg_band_mask &= ~ERTS_PSFLG_IN_RUNQ;
@@ -9632,9 +9725,11 @@ Process *schedule(Process *p, int calls)
 			       | ERTS_PSFLG_RUNNING_SYS))) {
 		    tmp = state & (ERTS_PSFLG_SUSPENDED
 				   | ERTS_PSFLG_PENDING_EXIT
-				   | ERTS_PSFLG_ACTIVE_SYS);
+				   | ERTS_PSFLG_ACTIVE_SYS
+				   | ERTS_PSFLG_DIRTY_ACTIVE_SYS);
 		    if (tmp != ERTS_PSFLG_SUSPENDED) {
-			if (state & ERTS_PSFLG_ACTIVE_SYS)
+			if (state & (ERTS_PSFLG_ACTIVE_SYS
+				     | ERTS_PSFLG_DIRTY_ACTIVE_SYS))
 			    new |= ERTS_PSFLG_RUNNING_SYS;
 			else
 			    new |= ERTS_PSFLG_RUNNING;
@@ -9647,7 +9742,8 @@ Process *schedule(Process *p, int calls)
 				  | ERTS_PSFLG_FREE))
 			|| ((state & (ERTS_PSFLG_SUSPENDED
 				      | ERTS_PSFLG_PENDING_EXIT
-				      | ERTS_PSFLG_ACTIVE_SYS))
+				      | ERTS_PSFLG_ACTIVE_SYS
+				      | ERTS_PSFLG_DIRTY_ACTIVE_SYS))
 			    == ERTS_PSFLG_SUSPENDED)) {
 			if (state & ERTS_PSFLG_FREE)
 			    erts_proc_dec_refc(p);
@@ -9666,10 +9762,42 @@ Process *schedule(Process *p, int calls)
 
 	    esdp->current_process = p;
 
+
+	    reds = context_reds;
+
+#ifdef ERTS_SMP
+
+	    erts_smp_runq_unlock(rq);
+
+#ifdef ERTS_DIRTY_SCHEDULERS
+	    if (ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+#ifdef DEBUG
+		int old_dqbit;
+#endif
+		int dqbit = qbit;
+
+		if (rq == ERTS_DIRTY_CPU_RUNQ)
+		    dqbit <<= ERTS_PDSFLGS_IN_CPU_PRQ_MASK_OFFSET;
+		else {
+		    ASSERT(rq == ERTS_DIRTY_IO_RUNQ);
+		    dqbit <<= ERTS_PDSFLGS_IN_IO_PRQ_MASK_OFFSET;
+		}
+
+#ifdef DEBUG
+		old_dqbit = (int)
+#else
+		    (void)
+#endif
+		    erts_smp_atomic32_read_band_mb(&p->dirty_state, ~dqbit);
+		ASSERT(old_dqbit & dqbit);
+	    }
+#endif /* ERTS_DIRTY_SCHEDULERS */
+
+#endif /* ERTS_SMP */
+
 	}
 
 #ifdef ERTS_SMP
-	erts_smp_runq_unlock(rq);
 
 	if (flags & ERTS_RUNQ_FLG_PROTECTED)
 	    (void) ERTS_RUNQ_FLGS_UNSET(rq, ERTS_RUNQ_FLG_PROTECTED);
@@ -9702,15 +9830,56 @@ Process *schedule(Process *p, int calls)
 	    erts_smp_spin_unlock(&erts_sched_stat.lock);
 	}
 
-	if (ERTS_PROC_PENDING_EXIT(p)) {
+	ASSERT(!p->scheduler_data);
+	p->scheduler_data = esdp;
+
+	state = erts_smp_atomic32_read_nob(&p->state);
+
+#ifdef ERTS_DIRTY_SCHEDULERS
+	if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
+	    if (!!(state & ERTS_PSFLGS_DIRTY_WORK)
+		& !(state & ERTS_PSFLG_ACTIVE_SYS)) {
+		/* Migrate to dirty scheduler... */
+	    sunlock_sched_out_proc:
+		erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
+		p->fcalls = reds;
+		goto sched_out_proc;
+
+	    }
+	}
+	else {
+	    if (state & (ERTS_PSFLG_ACTIVE_SYS
+			 | ERTS_PSFLG_PENDING_EXIT
+			 | ERTS_PSFLG_EXITING)) {
+		/* Migrate to normal scheduler... */
+		goto sunlock_sched_out_proc;
+	    }
+	    if ((state & ERTS_PSFLG_DIRTY_ACTIVE_SYS)
+		&& rq == ERTS_DIRTY_IO_RUNQ) {
+		/* Migrate to dirty cpu scheduler... */
+		goto sunlock_sched_out_proc;
+	    }
+
+	    ASSERT((state & ERTS_PSFLG_DIRTY_ACTIVE_SYS)
+		   || *p->i == (BeamInstr) em_call_nif);
+
+	    ASSERT(rq == ERTS_DIRTY_CPU_RUNQ
+		   ? (state & (ERTS_PSFLG_DIRTY_CPU_PROC
+			       | ERTS_PSFLG_DIRTY_ACTIVE_SYS))
+		   : (rq == ERTS_DIRTY_IO_RUNQ
+		      && (state & ERTS_PSFLG_DIRTY_IO_PROC)));	    
+	}
+#endif
+
+	if (state & ERTS_PSFLG_PENDING_EXIT) {
 	    erts_handle_pending_exit(p,
 				     ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_STATUS);
 	    state = erts_smp_atomic32_read_nob(&p->state);
 	}
-	ASSERT(!p->scheduler_data);
-	p->scheduler_data = esdp;
-#endif
-	reds = context_reds;
+
+#endif /* ERTS_SMP */
+
+	p->fcalls = reds;
 
 	if (IS_TRACED(p)) {
 	    if (state & ERTS_PSFLG_EXITING) {
@@ -9739,7 +9908,8 @@ Process *schedule(Process *p, int calls)
 	    reds -= execute_sys_tasks(p, &state, reds);
 	    if (reds <= 0
 #ifdef ERTS_DIRTY_SCHEDULERS
-		|| (state & (ERTS_PSFLG_DIRTY_CPU_PROC|ERTS_PSFLG_DIRTY_IO_PROC))
+		|| ERTS_SCHEDULER_IS_DIRTY(esdp)
+		|| (state & ERTS_PSFLGS_DIRTY_WORK)
 #endif
 		) {
 		p->fcalls = reds;
@@ -9787,7 +9957,6 @@ Process *schedule(Process *p, int calls)
 	    proxy_p = NULL;
 	}
 	    
-	p->fcalls = reds;
 	ERTS_SMP_CHK_HAVE_ONLY_MAIN_PROC_LOCK(p);
 
 	/* Never run a suspended process */
@@ -10732,6 +10901,9 @@ static void early_init_process_struct(void *varg, Eterm data)
     Process *proc = arg->proc;
 
     proc->common.id = make_internal_pid(data);
+#ifdef ERTS_DIRTY_SCHEDULERS
+    erts_smp_atomic32_init_nob(&proc->dirty_state, 0);
+#endif
     erts_smp_atomic32_init_relb(&proc->state, arg->state);
 
 #ifdef ERTS_SMP
@@ -11194,6 +11366,9 @@ void erts_init_empty_process(Process *p)
     p->last_old_htop = NULL;
 #endif
 
+#ifdef ERTS_DIRTY_SCHEDULERS
+    erts_smp_atomic32_init_nob(&p->dirty_state, 0);
+#endif
     erts_smp_atomic32_init_nob(&p->state, (erts_aint32_t) PRIORITY_NORMAL);
 
 #ifdef ERTS_SMP
@@ -11395,7 +11570,9 @@ set_proc_exiting(Process *p,
     ERTS_SMP_LC_ASSERT(erts_proc_lc_my_proc_locks(p) == ERTS_PROC_LOCKS_ALL);
 
     enqueue = change_proc_schedule_state(p,
-					 ERTS_PSFLG_SUSPENDED|ERTS_PSFLG_PENDING_EXIT,
+					 (ERTS_PSFLG_SUSPENDED
+					  | ERTS_PSFLG_PENDING_EXIT
+					  | ERTS_PSFLGS_DIRTY_WORK),
 					 ERTS_PSFLG_EXITING|ERTS_PSFLG_ACTIVE,
 					 &state,
 					 &enq_prio,
@@ -11429,10 +11606,7 @@ set_proc_exiting(Process *p,
     }
 #endif
 
-    if (enqueue)
-	add2runq(enqueue > 0 ? p : make_proxy_proc(NULL, p, enq_prio),
-		 state,
-		 enq_prio);
+    add2runq(enqueue, enq_prio, p, state, NULL);
 }
 
 static ERTS_INLINE erts_aint32_t
@@ -11535,6 +11709,11 @@ save_pending_exiter(Process *p)
     else
         rq = esdp->run_queue;
 
+#ifdef ERTS_DIRTY_SCHEDULERS
+    if (ERTS_RUNQ_IX_IS_DIRTY(rq->ix))
+	rq = ERTS_RUNQ_IX(0); /* Handle on ordinary scheduler */
+#endif
+
     plp = proclist_create(p);
 
     erts_smp_runq_lock(rq);
@@ -11544,13 +11723,8 @@ save_pending_exiter(Process *p)
     non_empty_runq(rq);
 
     erts_smp_runq_unlock(rq);
-#ifdef ERTS_DIRTY_SCHEDULERS
-    if (ERTS_RUNQ_IX_IS_DIRTY(rq->ix))
-	wake_dirty_schedulers(rq, 0);
-    else
-#endif
-	wake_scheduler(rq);
 
+    wake_scheduler(rq);
 }
 
 #endif
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index 10c6fa4a67..32e458aa1d 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -1033,6 +1033,9 @@ struct process {
     ErtsProcSysTaskQs *sys_task_qs;
 
     erts_smp_atomic32_t state;  /* Process state flags (see ERTS_PSFLG_*) */
+#ifdef ERTS_DIRTY_SCHEDULERS
+    erts_smp_atomic32_t dirty_state; /* Process dirty state flags (see ERTS_PDSFLG_*) */
+#endif
 
 #ifdef ERTS_SMP
     ErlMessageInQueue msg_inq;
@@ -1150,15 +1153,14 @@ void erts_check_for_holes(Process* p);
 #define ERTS_PSFLG_RUNNING_SYS		ERTS_PSFLG_BIT(15)
 #define ERTS_PSFLG_PROXY		ERTS_PSFLG_BIT(16)
 #define ERTS_PSFLG_DELAYED_SYS		ERTS_PSFLG_BIT(17)
-#ifdef ERTS_DIRTY_SCHEDULERS
 #define ERTS_PSFLG_DIRTY_CPU_PROC	ERTS_PSFLG_BIT(18)
 #define ERTS_PSFLG_DIRTY_IO_PROC	ERTS_PSFLG_BIT(19)
-#define ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q	ERTS_PSFLG_BIT(20)
-#define ERTS_PSFLG_DIRTY_IO_PROC_IN_Q	ERTS_PSFLG_BIT(21)
-#define ERTS_PSFLG_MAX  (ERTS_PSFLGS_ZERO_BIT_OFFSET + 22)
-#else
-#define ERTS_PSFLG_MAX  (ERTS_PSFLGS_ZERO_BIT_OFFSET + 18)
-#endif
+#define ERTS_PSFLG_DIRTY_ACTIVE_SYS	ERTS_PSFLG_BIT(20)
+#define ERTS_PSFLG_MAX  (ERTS_PSFLGS_ZERO_BIT_OFFSET + 20)
+
+#define ERTS_PSFLGS_DIRTY_WORK		(ERTS_PSFLG_DIRTY_CPU_PROC	\
+					 | ERTS_PSFLG_DIRTY_IO_PROC	\
+					 | ERTS_PSFLG_DIRTY_ACTIVE_SYS)
 
 #define ERTS_PSFLGS_IN_PRQ_MASK 	(ERTS_PSFLG_IN_PRQ_MAX		\
 					 | ERTS_PSFLG_IN_PRQ_HIGH	\
@@ -1170,7 +1172,37 @@ void erts_check_for_holes(Process* p);
 #define ERTS_PSFLGS_GET_USR_PRIO(PSFLGS) \
     (((PSFLGS) >> ERTS_PSFLGS_USR_PRIO_OFFSET) & ERTS_PSFLGS_PRIO_MASK)
 #define ERTS_PSFLGS_GET_PRQ_PRIO(PSFLGS) \
-    (((PSFLGS) >> ERTS_PSFLGS_USR_PRIO_OFFSET) & ERTS_PSFLGS_PRIO_MASK)
+    (((PSFLGS) >> ERTS_PSFLGS_PRQ_PRIO_OFFSET) & ERTS_PSFLGS_PRIO_MASK)
+
+#ifdef ERTS_DIRTY_SCHEDULERS
+
+/*
+ * Flags in the dirty_state field.
+ */
+
+#define ERTS_PDSFLG_IN_CPU_PRQ_MAX 	(((erts_aint32_t) 1) << 0)
+#define ERTS_PDSFLG_IN_CPU_PRQ_HIGH	(((erts_aint32_t) 1) << 1)
+#define ERTS_PDSFLG_IN_CPU_PRQ_NORMAL	(((erts_aint32_t) 1) << 2)
+#define ERTS_PDSFLG_IN_CPU_PRQ_LOW 	(((erts_aint32_t) 1) << 3)
+#define ERTS_PDSFLG_IN_IO_PRQ_MAX 	(((erts_aint32_t) 1) << 4)
+#define ERTS_PDSFLG_IN_IO_PRQ_HIGH	(((erts_aint32_t) 1) << 5)
+#define ERTS_PDSFLG_IN_IO_PRQ_NORMAL	(((erts_aint32_t) 1) << 6)
+#define ERTS_PDSFLG_IN_IO_PRQ_LOW 	(((erts_aint32_t) 1) << 7)
+
+#define ERTS_PDSFLGS_QMASK 		ERTS_PSFLGS_QMASK
+#define ERTS_PDSFLGS_IN_CPU_PRQ_MASK_OFFSET 0
+#define ERTS_PDSFLGS_IN_IO_PRQ_MASK_OFFSET ERTS_PSFLGS_QMASK_BITS
+
+#define ERTS_PDSFLG_IN_CPU_PRQ_MASK 	(ERTS_PDSFLG_IN_CPU_PRQ_MAX	\
+					 | ERTS_PDSFLG_IN_CPU_PRQ_HIGH	\
+					 | ERTS_PDSFLG_IN_CPU_PRQ_NORMAL\
+					 | ERTS_PDSFLG_IN_CPU_PRQ_LOW)
+#define ERTS_PDSFLG_IN_IO_PRQ_MASK 	(ERTS_PDSFLG_IN_CPU_PRQ_MAX	\
+					 | ERTS_PDSFLG_IN_CPU_PRQ_HIGH	\
+					 | ERTS_PDSFLG_IN_CPU_PRQ_NORMAL\
+					 | ERTS_PDSFLG_IN_CPU_PRQ_LOW)
+#endif
+
 
 /*
  * Static flags that do not change after process creation.
diff --git a/erts/emulator/beam/erl_process_dump.c b/erts/emulator/beam/erl_process_dump.c
index 25f0b1ed38..598c1d66ba 100644
--- a/erts/emulator/beam/erl_process_dump.c
+++ b/erts/emulator/beam/erl_process_dump.c
@@ -617,7 +617,7 @@ erts_dump_extended_process_state(int to, void *to_arg, erts_aint32_t psflg) {
     if (psflg)
         erts_print(to, to_arg, " | ");
 
-    for (i = 0; i < ERTS_PSFLG_MAX && psflg; i++) {
+    for (i = 0; i <= ERTS_PSFLG_MAX && psflg; i++) {
         erts_aint32_t chk = (1 << i);
         if (psflg & chk) {
             switch (chk) {
@@ -657,16 +657,12 @@ erts_dump_extended_process_state(int to, void *to_arg, erts_aint32_t psflg) {
                 erts_print(to, to_arg, "PROXY"); break;
             case ERTS_PSFLG_DELAYED_SYS:
                 erts_print(to, to_arg, "DELAYED_SYS"); break;
-#ifdef ERTS_DIRTY_SCHEDULERS
             case ERTS_PSFLG_DIRTY_CPU_PROC:
                 erts_print(to, to_arg, "DIRTY_CPU_PROC"); break;
             case ERTS_PSFLG_DIRTY_IO_PROC:
                 erts_print(to, to_arg, "DIRTY_IO_PROC"); break;
-            case ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q:
-                erts_print(to, to_arg, "DIRTY_CPU_PROC_IN_Q"); break;
-            case ERTS_PSFLG_DIRTY_IO_PROC_IN_Q:
-                erts_print(to, to_arg, "DIRTY_IO_PROC_IN_Q"); break;
-#endif
+            case ERTS_PSFLG_DIRTY_ACTIVE_SYS:
+                erts_print(to, to_arg, "DIRTY_ACTIVE_SYS"); break;
             default:
                 erts_print(to, to_arg, "UNKNOWN(%d)", chk); break;
             }