erts: Move fds with active true behaviour to own pollset

At start of the VM a poll-set that the schedulers
will check is created where fds that have triggered
many (at the moment, many means 10) times without
being deselected inbetween. In this scheduler specific
poll-set fds do not use ONESHOT, which means that the
number of syscalls goes down dramatically for such fds.

This pollset is introduced in order to handle fds that
are used by the erlang distribution and that never
change their state from {active, true}.

This pollset only handles ready_input events,
ready_output is still handled by the poll threads.

During overload, polling the scheduler poll-set is done
on a 10ms timer.

13 files changed, 843 insertions, 269 deletions

diff --git a/erts/emulator/beam/erl_port.h b/erts/emulator/beam/erl_port.h
index 2be0a5bf74..25976d38cc 100644
--- a/erts/emulator/beam/erl_port.h
+++ b/erts/emulator/beam/erl_port.h
@@ -334,6 +334,8 @@ Eterm erts_request_io_bytes(Process *c_p);
 #define ERTS_PORT_SFLG_INVALID		((Uint32) (1 << 11))
 /* Last port to terminate halts the emulator */
 #define ERTS_PORT_SFLG_HALT		((Uint32) (1 << 12))
+/* Check if the event in ready_input should be cleaned */
+#define ERTS_PORT_SFLG_CHECK_FD_CLEANUP ((Uint32) (1 << 13))
 #ifdef DEBUG
 /* Only debug: make sure all flags aren't cleared unintentionally */
 #define ERTS_PORT_SFLG_PORT_DEBUG	((Uint32) (1 << 31))
diff --git a/erts/emulator/beam/erl_port_task.c b/erts/emulator/beam/erl_port_task.c
index 4928d80f27..c8f2e88127 100644
--- a/erts/emulator/beam/erl_port_task.c
+++ b/erts/emulator/beam/erl_port_task.c
@@ -97,6 +97,9 @@ static void chk_task_queues(Port *pp, ErtsPortTask *execq, int processing_busy_q
 typedef union {
     struct { /* I/O tasks */
 	ErlDrvEvent event;
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+        int is_scheduler_event;
+#endif
     } io;
     struct {
 	ErtsProc2PortSigCallback callback;
@@ -141,6 +144,9 @@ struct ErtsPortTaskBusyCallerTable_ {
     ErtsPortTaskBusyCaller pre_alloc_busy_caller;
 };
 
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+erts_atomic_t erts_port_task_outstanding_io_tasks;
+#endif
 
 static void begin_port_cleanup(Port *pp,
 			       ErtsPortTask **execq,
@@ -578,13 +584,26 @@ reset_handle(ErtsPortTask *ptp)
 }
 
 static ERTS_INLINE void
-reset_executed_io_task_handle(ErtsPortTask *ptp)
+reset_executed_io_task_handle(Port *prt, ErtsPortTask *ptp)
 {
     if (ptp->u.alive.handle) {
 	ASSERT(ptp == handle2task(ptp->u.alive.handle));
-        /* The port task handle is reset inside task_executed */
-	erts_io_notify_port_task_executed(ptp->type, ptp->u.alive.handle,
-                                          reset_port_task_handle);
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+        if (ptp->u.alive.td.io.is_scheduler_event) {
+            if ((erts_atomic32_read_nob(&prt->state) & ERTS_PORT_SFLG_CHECK_FD_CLEANUP)) {
+                erts_io_notify_port_task_executed(ptp->type, ptp->u.alive.handle,
+                                                  reset_port_task_handle);
+                erts_atomic32_read_band_nob(&prt->state, ~ERTS_PORT_SFLG_CHECK_FD_CLEANUP);
+            } else {
+                reset_port_task_handle(ptp->u.alive.handle);
+            }
+        } else
+#endif
+        {
+            /* The port task handle is reset inside task_executed */
+            erts_io_notify_port_task_executed(ptp->type, ptp->u.alive.handle,
+                                              reset_port_task_handle);
+        }
     }
 }
 
@@ -1307,6 +1326,22 @@ erts_port_task_abort(ErtsPortTaskHandle *pthp)
 	    res = - 1; /* Task already aborted, executing, or executed */
 	else {
 	    reset_port_task_handle(pthp);
+
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+            switch (ptp->type) {
+	    case ERTS_PORT_TASK_INPUT:
+	    case ERTS_PORT_TASK_OUTPUT:
+                if (ptp->u.alive.td.io.is_scheduler_event) {
+                    ASSERT(erts_atomic_read_nob(
+                               &erts_port_task_outstanding_io_tasks) > 0);
+                    erts_atomic_dec_relb(&erts_port_task_outstanding_io_tasks);
+                }
+		break;
+	    default:
+		break;
+	    }
+#endif
+
 	    res = 0;
 	}
     }
@@ -1442,7 +1477,14 @@ erts_port_task_schedule(Eterm id,
 	va_list argp;
 	va_start(argp, type);
 	ptp->u.alive.td.io.event = va_arg(argp, ErlDrvEvent);
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+        ptp->u.alive.td.io.is_scheduler_event = va_arg(argp, int);
+#endif
 	va_end(argp);
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+        if (ptp->u.alive.td.io.is_scheduler_event)
+            erts_atomic_inc_relb(&erts_port_task_outstanding_io_tasks);
+#endif
 	break;
     }
     case ERTS_PORT_TASK_PROC_SIG: {
@@ -1621,12 +1663,14 @@ erts_port_task_execute(ErtsRunQueue *runq, Port **curr_port_pp)
     int processing_busy_q;
     int vreds = 0;
     int reds = 0;
-    erts_aint_t io_tasks_executed = 0;
     int fpe_was_unmasked;
     erts_aint32_t state;
     int active;
     Uint64 start_time = 0;
     ErtsSchedulerData *esdp = runq->scheduler;
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    erts_aint_t io_tasks_executed = 0;
+#endif
     ERTS_MSACC_PUSH_STATE_M();
 
     ERTS_LC_ASSERT(erts_lc_runq_is_locked(runq));
@@ -1722,8 +1766,11 @@ erts_port_task_execute(ErtsRunQueue *runq, Port **curr_port_pp)
 	       for input and output */
 	    (*pp->drv_ptr->ready_input)((ErlDrvData) pp->drv_data,
 					ptp->u.alive.td.io.event);
-	    reset_executed_io_task_handle(ptp);
-	    io_tasks_executed++;
+	    reset_executed_io_task_handle(pp, ptp);
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+            if (ptp->u.alive.td.io.is_scheduler_event)
+                io_tasks_executed++;
+#endif
 	    break;
 	case ERTS_PORT_TASK_OUTPUT:
 	    reds = ERTS_PORT_REDS_OUTPUT;
@@ -1732,8 +1779,11 @@ erts_port_task_execute(ErtsRunQueue *runq, Port **curr_port_pp)
             LTTNG_DRIVER(driver_ready_output, pp);
 	    (*pp->drv_ptr->ready_output)((ErlDrvData) pp->drv_data,
 					 ptp->u.alive.td.io.event);
-	    reset_executed_io_task_handle(ptp);
-	    io_tasks_executed++;
+	    reset_executed_io_task_handle(pp, ptp);
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+            if (ptp->u.alive.td.io.is_scheduler_event)
+                io_tasks_executed++;
+#endif
 	    break;
 	case ERTS_PORT_TASK_PROC_SIG: {
 	    ErtsProc2PortSigData *sigdp = &ptp->u.alive.td.psig.data;
@@ -1799,6 +1849,15 @@ erts_port_task_execute(ErtsRunQueue *runq, Port **curr_port_pp)
     erts_unblock_fpe(fpe_was_unmasked);
     ERTS_MSACC_POP_STATE_M();
 
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    if (io_tasks_executed) {
+        ASSERT(erts_atomic_read_nob(&erts_port_task_outstanding_io_tasks)
+	       >= io_tasks_executed);
+        erts_atomic_add_relb(&erts_port_task_outstanding_io_tasks,
+				 -1*io_tasks_executed);
+    }
+#endif
+
     ASSERT(runq == erts_get_runq_port(pp));
 
     active = finalize_exec(pp, &execq, processing_busy_q);
@@ -2086,6 +2145,10 @@ erts_dequeue_port(ErtsRunQueue *rq)
 void
 erts_port_task_init(void)
 {
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    erts_atomic_init_nob(&erts_port_task_outstanding_io_tasks,
+                         (erts_aint_t) 0);
+#endif    
     init_port_task_alloc(erts_no_schedulers + erts_no_poll_threads
                          + 1); /* aux_thread */
     init_busy_caller_table_alloc();
diff --git a/erts/emulator/beam/erl_port_task.h b/erts/emulator/beam/erl_port_task.h
index ae78a7d8a3..ca5183b305 100644
--- a/erts/emulator/beam/erl_port_task.h
+++ b/erts/emulator/beam/erl_port_task.h
@@ -38,6 +38,8 @@ typedef erts_atomic_t ErtsPortTaskHandle;
 #ifndef ERL_PORT_TASK_H__
 #define ERL_PORT_TASK_H__
 
+#include "erl_poll.h"
+
 #undef ERTS_INCLUDE_SCHEDULER_INTERNALS
 #if (defined(ERL_PROCESS_C__) \
      || defined(ERL_PORT_TASK_C__) \
@@ -54,8 +56,8 @@ typedef erts_atomic_t ErtsPortTaskHandle;
 #define ERTS_PT_FLG_BAD_OUTPUT		(1 << 4)
 
 typedef enum {
-    ERTS_PORT_TASK_INPUT,
-    ERTS_PORT_TASK_OUTPUT,
+    ERTS_PORT_TASK_INPUT = 0,
+    ERTS_PORT_TASK_OUTPUT = 1,
     ERTS_PORT_TASK_TIMEOUT,
     ERTS_PORT_TASK_DIST_CMD,
     ERTS_PORT_TASK_PROC_SIG
@@ -134,6 +136,12 @@ ERTS_GLB_INLINE void erts_port_task_sched_unlock(ErtsPortTaskSched *ptsp);
 ERTS_GLB_INLINE int erts_port_task_sched_lock_is_locked(ErtsPortTaskSched *ptsp);
 ERTS_GLB_INLINE void erts_port_task_sched_enter_exiting_state(ErtsPortTaskSched *ptsp);
 
+#if defined(ERTS_INCLUDE_SCHEDULER_INTERNALS) && ERTS_POLL_USE_SCHEDULER_POLLING
+ERTS_GLB_INLINE int erts_port_task_have_outstanding_io_tasks(void);
+/* NOTE: Do not access any of the exported variables directly */
+extern erts_atomic_t erts_port_task_outstanding_io_tasks;
+#endif
+
 #if ERTS_GLB_INLINE_INCL_FUNC_DEF
 
 ERTS_GLB_INLINE void
@@ -211,6 +219,15 @@ erts_port_task_sched_enter_exiting_state(ErtsPortTaskSched *ptsp)
     erts_atomic32_read_bor_nob(&ptsp->flags, ERTS_PTS_FLG_EXITING);
 }
 
+#if defined(ERTS_INCLUDE_SCHEDULER_INTERNALS) && ERTS_POLL_USE_SCHEDULER_POLLING
+ERTS_GLB_INLINE int
+erts_port_task_have_outstanding_io_tasks(void)
+{
+    return (erts_atomic_read_acqb(&erts_port_task_outstanding_io_tasks)
+	    != 0);
+}
+#endif
+
 #endif
 
 #ifdef ERTS_INCLUDE_SCHEDULER_INTERNALS
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 919d9f9edf..2427d87f66 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -174,7 +174,6 @@ ErtsLcPSDLocks erts_psd_required_locks[ERTS_PSD_SIZE];
 typedef struct {
     int aux_work;
     int tse;
-    int sys_schedule;
 } ErtsBusyWaitParams;
 
 static ErtsBusyWaitParams sched_busy_wait_params[ERTS_SCHED_TYPE_LAST + 1];
@@ -344,6 +343,9 @@ erts_sched_stat_t erts_sched_stat;
 
 static erts_tsd_key_t ERTS_WRITE_UNLIKELY(sched_data_key);
 
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+static erts_atomic32_t doing_sys_schedule;
+#endif
 static erts_atomic32_t no_empty_run_queues;
 long erts_runq_supervision_interval = 0;
 static ethr_event runq_supervision_event;
@@ -3093,8 +3095,12 @@ aux_thread(void *unused)
     awdp->ssi = ssi;
 
 #if ERTS_POLL_USE_FALLBACK
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    ssi->psi = erts_create_pollset_thread(-2, tpd);
+#else
     ssi->psi = erts_create_pollset_thread(-1, tpd);
 #endif
+#endif
 
     sched_prep_spin_wait(ssi);
 
@@ -3133,7 +3139,7 @@ aux_thread(void *unused)
 		if (flgs & ERTS_SSI_FLG_SLEEPING) {
 		    ASSERT(flgs & ERTS_SSI_FLG_POLL_SLEEPING);
 		    ASSERT(flgs & ERTS_SSI_FLG_WAITING);
-                    erts_check_io(ssi->psi);
+                    erts_check_io(ssi->psi, ERTS_POLL_INF_TIMEOUT);
 		}
             }
 #else
@@ -3231,7 +3237,7 @@ poll_thread(void *arg)
 		if (flgs & ERTS_SSI_FLG_SLEEPING) {
 		    ASSERT(flgs & ERTS_SSI_FLG_POLL_SLEEPING);
 		    ASSERT(flgs & ERTS_SSI_FLG_WAITING);
-                    erts_check_io(psi);
+                    erts_check_io(psi, ERTS_POLL_INF_TIMEOUT);
 		}
 	    }
 	}
@@ -3241,6 +3247,59 @@ poll_thread(void *arg)
     return NULL;
 }
 
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+static ERTS_INLINE void
+clear_sys_scheduling(void)
+{
+    erts_atomic32_set_mb(&doing_sys_schedule, 0);
+}
+
+static ERTS_INLINE int
+try_set_sys_scheduling(void)
+{
+    return 0 == erts_atomic32_cmpxchg_acqb(&doing_sys_schedule, 1, 0);
+}
+
+
+static ERTS_INLINE int
+prepare_for_sys_schedule(void)
+{
+    while (!erts_port_task_have_outstanding_io_tasks()
+           && try_set_sys_scheduling()) {
+        if (!erts_port_task_have_outstanding_io_tasks())
+            return 1;
+        clear_sys_scheduling();
+    }
+    return 0;
+}
+
+static void
+check_io_timer(void *null)
+{
+    ErtsSchedulerData *esdp = erts_get_scheduler_data();
+    if (prepare_for_sys_schedule()) {
+        erts_check_io(esdp->ssi->psi, ERTS_POLL_NO_TIMEOUT);
+        clear_sys_scheduling();
+    }
+
+    /* The timer is cleared if this schedulers run-queue became empty
+       or if the CHECKIO flag was cleared. The CHECKIO flags is cleared
+       when a check_balance assigns another scheduler to be the poller in
+       the overload scenario. */
+    if ((ERTS_RUNQ_FLGS_GET_NOB(esdp->run_queue) & (ERTS_RUNQ_FLG_OUT_OF_WORK|ERTS_RUNQ_FLG_CHECKIO))
+        == ERTS_RUNQ_FLG_CHECKIO) {
+        erts_start_timer_callback(ERTS_POLL_SCHEDULER_POLLING_TIMEOUT,
+                                  check_io_timer, NULL);
+    } else {
+        ERTS_RUNQ_FLGS_UNSET(esdp->run_queue, ERTS_RUNQ_FLG_CHECKIO);
+    }
+}
+
+#else
+#define clear_sys_scheduling()
+#define prepare_for_sys_schedule() 0
+#endif
+
 static void
 scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 {
@@ -3330,7 +3389,25 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
                     sched_wall_time_change(esdp, 1);
                 }
             }
-            else {
+            else if (!ERTS_SCHEDULER_IS_DIRTY(esdp) && prepare_for_sys_schedule()) {
+                /* We sleep in check_io, only for normal schedulers */
+                if (thr_prgr_active) {
+                    erts_thr_progress_active(erts_thr_prgr_data(esdp), thr_prgr_active = 0);
+                    sched_wall_time_change(esdp, 0);
+                }
+                flgs = sched_spin_wait(ssi, 0);
+                if (flgs & ERTS_SSI_FLG_SLEEPING) {
+                    ASSERT(flgs & ERTS_SSI_FLG_WAITING);
+                    flgs = sched_set_sleeptype(ssi, ERTS_SSI_FLG_POLL_SLEEPING);
+                    if (flgs & ERTS_SSI_FLG_SLEEPING) {
+                        ASSERT(flgs & ERTS_SSI_FLG_POLL_SLEEPING);
+                        ASSERT(flgs & ERTS_SSI_FLG_WAITING);
+                        erts_check_io(ssi->psi, timeout_time);
+                        current_time = erts_get_monotonic_time(esdp);
+                    }
+                }
+                clear_sys_scheduling();
+            } else {
                 if (!ERTS_SCHEDULER_IS_DIRTY(esdp)) {
                     if (thr_prgr_active) {
                         erts_thr_progress_active(erts_thr_prgr_data(esdp), thr_prgr_active = 0);
@@ -3338,7 +3415,6 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
                     }
                     erts_thr_progress_prepare_wait(erts_thr_prgr_data(esdp));
                 }
-
                 flgs = sched_spin_wait(ssi, spincount);
                 if (flgs & ERTS_SSI_FLG_SLEEPING) {
                     ASSERT(flgs & ERTS_SSI_FLG_WAITING);
@@ -4585,6 +4661,15 @@ check_balance(ErtsRunQueue *c_rq)
     if (blnc_no_rqs == 1) {
 	c_rq->check_balance_reds = INT_MAX;
 	erts_atomic32_set_nob(&balance_info.checking_balance, 0);
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+	c_rq->check_balance_reds = ERTS_RUNQ_CALL_CHECK_BALANCE_REDS;
+        if ((ERTS_RUNQ_FLGS_GET_NOB(c_rq) & (ERTS_RUNQ_FLG_OUT_OF_WORK|ERTS_RUNQ_FLG_CHECKIO))
+             == 0) {
+            ERTS_RUNQ_FLGS_SET(c_rq, ERTS_RUNQ_FLG_CHECKIO);
+            erts_start_timer_callback(ERTS_POLL_SCHEDULER_POLLING_TIMEOUT, check_io_timer, NULL);
+        }
+        ERTS_RUNQ_FLGS_UNSET(c_rq, ERTS_RUNQ_FLGS_MIGRATION_INFO);
+#endif
 	return;
     }
 
@@ -5104,6 +5189,19 @@ erts_fprintf(stderr, "--------------------------------\n");
     /* Publish new migration paths... */
     erts_atomic_set_wb(&erts_migration_paths, (erts_aint_t) new_mpaths);
 
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    if (full_scheds == current_active) {
+        ERTS_ASSERT(full_scheds <= current_active);
+        /* All active schedulers ran for full, we need to do active polling,
+           so we setup a timer that does active polling */
+        if (!(ERTS_RUNQ_FLGS_GET_NOB(c_rq) & ERTS_RUNQ_FLG_CHECKIO)) {
+            /* Active polling is not running, start it */
+            erts_start_timer_callback(ERTS_POLL_SCHEDULER_POLLING_TIMEOUT, check_io_timer, NULL);
+        }
+        run_queue_info[c_rq->ix].flags |= ERTS_RUNQ_FLG_CHECKIO;
+    }
+#endif
+
     /* Reset balance statistics in all online queues */
     for (qix = 0; qix < blnc_no_rqs; qix++) {
 	Uint32 flags = run_queue_info[qix].flags;
@@ -5113,6 +5211,8 @@ erts_fprintf(stderr, "--------------------------------\n");
 	ASSERT(!(flags & ERTS_RUNQ_FLG_OUT_OF_WORK));
 	if (rq->waiting)
 	    flags |= ERTS_RUNQ_FLG_OUT_OF_WORK;
+        if (rq != c_rq)
+            flags &= ~ERTS_RUNQ_FLG_CHECKIO;
 
 	rq->full_reds_history_sum
 	    = run_queue_info[qix].full_reds_history_sum;
@@ -5122,8 +5222,7 @@ erts_fprintf(stderr, "--------------------------------\n");
 	ERTS_DBG_CHK_FULL_REDS_HISTORY(rq);
 
 	rq->out_of_work_count = 0;
-	(void) ERTS_RUNQ_FLGS_READ_BSET(rq, ERTS_RUNQ_FLGS_MIGRATION_INFO, flags);
-
+	(void) ERTS_RUNQ_FLGS_READ_BSET(rq, ERTS_RUNQ_FLGS_MIGRATION_INFO|ERTS_RUNQ_FLG_CHECKIO, flags);
 	rq->max_len = erts_atomic32_read_dirty(&rq->len);
 	for (pix = 0; pix < ERTS_NO_PRIO_LEVELS; pix++) {
 	    ErtsRunQueueInfo *rqi;
@@ -5562,7 +5661,6 @@ erts_sched_set_busy_wait_threshold(ErtsSchedType sched_type, char *str)
 	return EINVAL;
     }
 
-    params->sys_schedule = sys_sched;
     params->tse = sys_sched * ERTS_SCHED_TSE_SLEEP_SPINCOUNT_FACT;
     params->aux_work = sys_sched * aux_work_fact;
 
@@ -5773,6 +5871,9 @@ erts_init_scheduling(int no_schedulers, int no_schedulers_online, int no_poll_th
     size_runqs = sizeof(ErtsAlignedRunQueue) * tot_rqs;
     erts_aligned_run_queues =
 	erts_alloc_permanent_cache_aligned(ERTS_ALC_T_RUNQS, size_runqs);
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    erts_atomic32_init_nob(&doing_sys_schedule, 0);
+#endif
     erts_atomic32_init_nob(&no_empty_run_queues, 0);
 
     erts_no_run_queues = n;
@@ -8302,6 +8403,11 @@ sched_thread_func(void *vesdp)
     erts_msacc_init_thread("scheduler", no, 1);
 
     erts_thr_progress_register_managed_thread(esdp, &callbacks, 0);
+
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    esdp->ssi->psi = erts_create_pollset_thread(-1, NULL);
+#endif
+
     erts_alloc_register_scheduler(vesdp);
 #ifdef ERTS_ENABLE_LOCK_CHECK
     {
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index 8d20ccdf90..a1b029adbe 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -173,8 +173,10 @@ extern int erts_dio_sched_thread_suggested_stack_size;
   (((Uint32) 1) << (ERTS_RUNQ_FLG_BASE2 + 9))
 #define ERTS_RUNQ_FLG_HALTING \
   (((Uint32) 1) << (ERTS_RUNQ_FLG_BASE2 + 10))
+#define ERTS_RUNQ_FLG_CHECKIO \
+  (((Uint32) 1) << (ERTS_RUNQ_FLG_BASE2 + 11))
 
-#define ERTS_RUNQ_FLG_MAX (ERTS_RUNQ_FLG_BASE2 + 11)
+#define ERTS_RUNQ_FLG_MAX (ERTS_RUNQ_FLG_BASE2 + 12)
 
 #define ERTS_RUNQ_FLGS_MIGRATION_QMASKS	\
   (ERTS_RUNQ_FLGS_EMIGRATE_QMASK	\
diff --git a/erts/emulator/sys/common/erl_check_io.c b/erts/emulator/sys/common/erl_check_io.c
index 1444cee805..c681fa481f 100644
--- a/erts/emulator/sys/common/erl_check_io.c
+++ b/erts/emulator/sys/common/erl_check_io.c
@@ -46,11 +46,11 @@
 #if 0
 #define DEBUG_PRINT(FMT, ...) erts_printf(FMT "\r\n", ##__VA_ARGS__)
 #define DEBUG_PRINT_FD(FMT, STATE, ...)                                 \
-    DEBUG_PRINT("%d: " FMT " (ev=%s, ac=%s, flg=%d)",                   \
+    DEBUG_PRINT("%d: " FMT " (ev=%s, ac=%s, flg=%s)",                   \
                 (STATE) ? (STATE)->fd : (ErtsSysFdType)-1, ##__VA_ARGS__, \
                 ev2str((STATE) ? (STATE)->events : ERTS_POLL_EV_NONE),  \
                 ev2str((STATE) ? (STATE)->active_events : ERTS_POLL_EV_NONE), \
-                (STATE) ? (STATE)->flags : ERTS_EV_FLAG_CLEAR)
+                (STATE) ? flag2str((STATE)->flags) : ERTS_EV_FLAG_CLEAR)
 #define DEBUG_PRINT_MODE
 #else
 #define DEBUG_PRINT(...)
@@ -76,22 +76,40 @@ typedef enum {
 typedef enum {
     ERTS_EV_FLAG_CLEAR         = 0,
     ERTS_EV_FLAG_USED          = 1,   /* ERL_DRV_USE has been turned on */
-#ifdef ERTS_ENABLE_KERNEL_POLL
-    ERTS_EV_FLAG_FALLBACK      = 2,   /* Set when kernel poll rejected fd
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    ERTS_EV_FLAG_SCHEDULER     = 2,   /* Set when the fd has been migrated
+                                         to scheduler pollset */
+    ERTS_EV_FLAG_IN_SCHEDULER  = 4,   /* Set when the fd is currently in
+                                         scheduler pollset */
+#else
+    ERTS_EV_FLAG_SCHEDULER     = ERTS_EV_FLAG_CLEAR,
+    ERTS_EV_FLAG_IN_SCHEDULER  = ERTS_EV_FLAG_CLEAR,
+#endif
+#ifdef ERTS_POLL_USE_FALLBACK
+    ERTS_EV_FLAG_FALLBACK      = 8,   /* Set when kernel poll rejected fd
                                          and it was put in the nkp version */
 #else
     ERTS_EV_FLAG_FALLBACK      = ERTS_EV_FLAG_CLEAR,
 #endif
 
     /* Combinations */
-    ERTS_EV_FLAG_USED_FALLBACK = ERTS_EV_FLAG_USED | ERTS_EV_FLAG_FALLBACK
+    ERTS_EV_FLAG_USED_FALLBACK = ERTS_EV_FLAG_USED | ERTS_EV_FLAG_FALLBACK,
+    ERTS_EV_FLAG_USED_SCHEDULER = ERTS_EV_FLAG_USED | ERTS_EV_FLAG_SCHEDULER,
+    ERTS_EV_FLAG_USED_IN_SCHEDULER = ERTS_EV_FLAG_USED | ERTS_EV_FLAG_SCHEDULER | ERTS_EV_FLAG_IN_SCHEDULER,
+    ERTS_EV_FLAG_UNUSED_SCHEDULER = ERTS_EV_FLAG_SCHEDULER,
+    ERTS_EV_FLAG_UNUSED_IN_SCHEDULER = ERTS_EV_FLAG_SCHEDULER | ERTS_EV_FLAG_IN_SCHEDULER
 } EventStateFlags;
 
 #define flag2str(flags)                                                 \
     ((flags) == ERTS_EV_FLAG_CLEAR ? "CLEAR" :                          \
      ((flags) == ERTS_EV_FLAG_USED ? "USED" :                           \
       ((flags) == ERTS_EV_FLAG_FALLBACK ? "FLBK" :                      \
-       ((flags) == ERTS_EV_FLAG_USED_FALLBACK ? "USED|FLBK" : "ERROR"))))
+       ((flags) == ERTS_EV_FLAG_USED_FALLBACK ? "USED|FLBK" :           \
+        ((flags) == ERTS_EV_FLAG_USED_SCHEDULER ? "USED|SCHD" :         \
+         ((flags) == ERTS_EV_FLAG_UNUSED_SCHEDULER ? "SCHD" :           \
+          ((flags) == ERTS_EV_FLAG_USED_IN_SCHEDULER ? "USED|IN_SCHD" : \
+           ((flags) == ERTS_EV_FLAG_UNUSED_IN_SCHEDULER ? "IN_SCHD" :   \
+            "ERROR"))))))))
 
 /* How many events that can be handled at once by one erts_poll_wait call */
 #define ERTS_CHECK_IO_POLL_RES_LEN 512
@@ -113,10 +131,13 @@ typedef struct erts_poll_thread
  * Which pollset to use is determined by hashing the fd.
  */
 static ErtsPollSet **pollsetv;
+static ErtsPollThread *psiv;
 #if ERTS_POLL_USE_FALLBACK
 static ErtsPollSet *flbk_pollset;
 #endif
-static ErtsPollThread *psiv;
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+static ErtsPollSet *sched_pollset;
+#endif
 
 typedef struct {
 #ifndef ERTS_SYS_CONTINOUS_FD_NUMBERS
@@ -131,10 +152,12 @@ typedef struct {
             ErtsResource* resource;   /* ERTS_EV_TYPE_STOP_NIF */
         } stop;
     } driver;
-    ErtsPollEvents events; /* The events that have been selected upon */
+    ErtsPollEvents events;        /* The events that have been selected upon */
     ErtsPollEvents active_events; /* The events currently active in the pollset */
     EventStateType type;
     EventStateFlags flags;
+    int count;                    /* Number of times this fd has triggered
+                                     without being deselected. */
 } ErtsDrvEventState;
 
 struct drv_ev_state_shared {
@@ -371,12 +394,22 @@ get_pollset(ErtsSysFdType fd)
 
 #if ERTS_POLL_USE_FALLBACK
 static ERTS_INLINE ErtsPollSet *
-get_fallback(void)
+get_fallback_pollset(void)
 {
     return flbk_pollset;
 }
 #endif
 
+static ERTS_INLINE ErtsPollSet *
+get_scheduler_pollset(ErtsSysFdType fd)
+{
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    return sched_pollset;
+#else
+    return get_pollset(fd);
+#endif
+}
+
 /*
  * Place a fd within a pollset. This will automatically use
  * the fallback ps if needed.
@@ -392,18 +425,27 @@ erts_io_control_wakeup(ErtsDrvEventState *state, ErtsPollOp op,
     ERTS_LC_ASSERT(erts_lc_mtx_is_locked(fd_mtx(state->fd)));
 
     if (!(flags & ERTS_EV_FLAG_FALLBACK)) {
-        res = erts_poll_control(get_pollset(fd), fd, op, pe, wake_poller);
+
+        if (op == ERTS_POLL_OP_DEL && (flags & ERTS_EV_FLAG_SCHEDULER)) {
+            erts_poll_control(get_scheduler_pollset(fd), fd, op, pe, wake_poller);
+            flags &= ~ERTS_EV_FLAG_IN_SCHEDULER;
+        }
+        if (!(flags & ERTS_EV_FLAG_IN_SCHEDULER) || (pe & ERTS_POLL_EV_OUT)) {
+            res = erts_poll_control(get_pollset(fd), fd, op, pe, wake_poller);
+        } else {
+            res = erts_poll_control(get_scheduler_pollset(fd), fd, op, pe, wake_poller);
+        }
 
 #if ERTS_POLL_USE_FALLBACK
         if (op == ERTS_POLL_OP_ADD && res == ERTS_POLL_EV_NVAL) {
             /* When an add fails with NVAL, the poll/kevent operation could not
                put that fd in the pollset, so we instead put it into a fallback pollset */
             state->flags |= ERTS_EV_FLAG_FALLBACK;
-            res = erts_poll_control_flbk(get_fallback(), fd, op, pe, wake_poller);
+            res = erts_poll_control_flbk(get_fallback_pollset(), fd, op, pe, wake_poller);
         }
     } else {
         ASSERT(op != ERTS_POLL_OP_ADD);
-        res = erts_poll_control_flbk(get_fallback(), fd, op, pe, wake_poller);
+        res = erts_poll_control_flbk(get_fallback_pollset(), fd, op, pe, wake_poller);
 #endif
     }
 
@@ -426,7 +468,8 @@ erts_io_notify_port_task_executed(ErtsPortTaskType type,
     ErtsIoTask *itp = ErtsContainerStruct(pthp, ErtsIoTask, task);
     ErtsSysFdType fd = itp->fd;
     erts_mtx_t *mtx = fd_mtx(fd);
-    int active_events;
+    ErtsPollOp op = ERTS_POLL_OP_MOD;
+    int active_events, new_events = 0;
     ErtsDrvEventState *state;
     ErtsDrvSelectDataState *free_select = NULL;
     ErtsNifSelectDataState *free_nif = NULL;
@@ -436,51 +479,66 @@ erts_io_notify_port_task_executed(ErtsPortTaskType type,
     erts_mtx_lock(mtx);
     state = get_drv_ev_state(fd);
 
+    reset_handle(pthp);
+
     active_events = state->active_events;
 
-    switch (type) {
-    case ERTS_PORT_TASK_INPUT:
+    if (!(state->flags & ERTS_EV_FLAG_IN_SCHEDULER) || type == ERTS_PORT_TASK_OUTPUT) {
+        switch (type) {
+        case ERTS_PORT_TASK_INPUT:
+
+            DEBUG_PRINT_FD("executed ready_input", state);
+
+            ASSERT(!(state->active_events & ERTS_POLL_EV_IN));
+            if (state->events & ERTS_POLL_EV_IN) {
+                active_events |= ERTS_POLL_EV_IN;
+                if (state->count > 10 && ERTS_POLL_USE_SCHEDULER_POLLING) {
+                    if (!(state->flags & ERTS_EV_FLAG_SCHEDULER))
+                        op = ERTS_POLL_OP_ADD;
+                    state->flags |= ERTS_EV_FLAG_IN_SCHEDULER|ERTS_EV_FLAG_SCHEDULER;
+                    new_events = ERTS_POLL_EV_IN;
+                    DEBUG_PRINT_FD("moving to scheduler ps", state);
+                } else
+                    new_events = active_events;
+                if (!(state->flags & ERTS_EV_FLAG_FALLBACK) && ERTS_POLL_USE_SCHEDULER_POLLING)
+                    state->count++;
+            }
+            break;
+        case ERTS_PORT_TASK_OUTPUT:
 
-        DEBUG_PRINT_FD("executed ready_input", state);
+            DEBUG_PRINT_FD("executed ready_output", state);
 
-        ASSERT(!(state->active_events & ERTS_POLL_EV_IN));
-        if (state->events & ERTS_POLL_EV_IN)
-            active_events |= ERTS_POLL_EV_IN;
-        break;
-    case ERTS_PORT_TASK_OUTPUT:
+            ASSERT(!(state->active_events & ERTS_POLL_EV_OUT));
+            if (state->events & ERTS_POLL_EV_OUT) {
+                active_events |= ERTS_POLL_EV_OUT;
+                if (state->flags & ERTS_EV_FLAG_IN_SCHEDULER && active_events & ERTS_POLL_EV_IN)
+                    new_events = ERTS_POLL_EV_OUT;
+                else
+                    new_events = active_events;
+            }
+            break;
+        default:
+            erts_exit(ERTS_ABORT_EXIT, "Invalid IO port task type");
+            break;
+        }
 
-        DEBUG_PRINT_FD("executed ready_output", state);
+        if (state->active_events != active_events && new_events) {
+            state->active_events = active_events;
+            new_events = erts_io_control(state, op, new_events);
+        }
 
-        ASSERT(!(state->active_events & ERTS_POLL_EV_OUT));
-        if (state->events & ERTS_POLL_EV_OUT)
-            active_events |= ERTS_POLL_EV_OUT;
-        break;
-    default:
-        erts_exit(ERTS_ABORT_EXIT, "Invalid IO port task type");
-        break;
+        /* We were unable to re-insert the fd into the pollset, signal the callback. */
+        if (new_events & (ERTS_POLL_EV_ERR|ERTS_POLL_EV_NVAL)) {
+            if (state->active_events & ERTS_POLL_EV_IN)
+                iready(state->driver.select->inport, state);
+            if (state->active_events & ERTS_POLL_EV_OUT)
+                oready(state->driver.select->outport, state);
+            state->active_events = 0;
+        }
     }
 
-    reset_handle(pthp);
-
-    if (active_events) {
-        /* This is not needed if active_events has not changed */
-        if (state->active_events != active_events) {
-            ErtsPollEvents new_events;
-            state->active_events = active_events;
-            new_events = erts_io_control(state, ERTS_POLL_OP_MOD, active_events);
-
-            /* We were unable to re-insert the fd into the pollset, signal the callback. */
-            if (new_events & (ERTS_POLL_EV_ERR|ERTS_POLL_EV_NVAL)) {
-                if (active_events & ERTS_POLL_EV_IN)
-                    iready(state->driver.select->inport, state);
-                if (active_events & ERTS_POLL_EV_OUT)
-                    oready(state->driver.select->outport, state);
-                state->active_events = 0;
-            }
-        }
-    } else {
+    if (!active_events)
         check_fd_cleanup(state, &free_select, &free_nif);
-    }
 
     erts_mtx_unlock(mtx);
 
@@ -760,11 +818,22 @@ driver_select(ErlDrvPort ix, ErlDrvEvent e, int mode, int on)
         if (old_events == 0 && !(state->flags & ERTS_EV_FLAG_USED)) {
             ctl_op = ERTS_POLL_OP_ADD;
         }
+        new_events = state->active_events;
+        if (state->flags & ERTS_EV_FLAG_IN_SCHEDULER)
+            new_events &= ~ERTS_POLL_EV_IN;
     }
     else {
         ctl_events &= old_events;
         state->events &= ~ctl_events;
         state->active_events &= ~ctl_events;
+        new_events = state->active_events;
+
+        if (ctl_events & ERTS_POLL_EV_IN) {
+            state->count = 0;
+            if (state->flags & ERTS_EV_FLAG_IN_SCHEDULER) {
+                new_events = 0;
+            }
+        }
 
         if (!state->events) {
             if (!(state->flags & ERTS_EV_FLAG_USED) || mode & ERL_DRV_USE)
@@ -775,7 +844,7 @@ driver_select(ErlDrvPort ix, ErlDrvEvent e, int mode, int on)
     if (ctl_events || ctl_op == ERTS_POLL_OP_DEL) {
 
         new_events = erts_io_control_wakeup(state, ctl_op,
-                                            state->active_events,
+                                            new_events,
                                             &wake_poller);
 
         ASSERT(state->type == ERTS_EV_TYPE_DRV_SEL || state->type == ERTS_EV_TYPE_NONE);
@@ -807,6 +876,7 @@ driver_select(ErlDrvPort ix, ErlDrvEvent e, int mode, int on)
             if (ctl_events & ERTS_POLL_EV_IN) {
                 abort_tasks(state, ERL_DRV_READ);
                 state->driver.select->inport = NIL;
+                state->flags &= ~ERTS_EV_FLAG_IN_SCHEDULER;
             }
             if (ctl_events & ERTS_POLL_EV_OUT) {
                 abort_tasks(state, ERL_DRV_WRITE);
@@ -815,6 +885,8 @@ driver_select(ErlDrvPort ix, ErlDrvEvent e, int mode, int on)
             if (state->events == 0) {
                 if ((mode & ERL_DRV_USE) || !(state->flags & ERTS_EV_FLAG_USED)) {
                     state->type = ERTS_EV_TYPE_NONE;
+                    if (state->flags & ERTS_EV_FLAG_SCHEDULER)
+                        erts_atomic32_read_bor_nob(&prt->state, ERTS_PORT_SFLG_CHECK_FD_CLEANUP);
                     state->flags = 0;
                 }
                 /*else keep it, as fd will probably be selected upon again */
@@ -1431,7 +1503,8 @@ iready(Eterm id, ErtsDrvEventState *state)
 	if (erts_port_task_schedule(id,
 				    &iotask->task,
 				    ERTS_PORT_TASK_INPUT,
-				    (ErlDrvEvent) state->fd) != 0) {
+				    (ErlDrvEvent) state->fd,
+                                    state->flags & ERTS_EV_FLAG_IN_SCHEDULER) != 0) {
 	    stale_drv_select(id, state, ERL_DRV_READ);
 	} else {
             DEBUG_PRINT_FD("schedule ready_input(%T, %d)",
@@ -1449,7 +1522,8 @@ oready(Eterm id, ErtsDrvEventState *state)
 	if (erts_port_task_schedule(id,
 				    &iotask->task,
 				    ERTS_PORT_TASK_OUTPUT,
-				    (ErlDrvEvent) state->fd) != 0) {
+				    (ErlDrvEvent) state->fd,
+                                    0) != 0) {
 	    stale_drv_select(id, state, ERL_DRV_WRITE);
 	} else {
             DEBUG_PRINT_FD("schedule ready_output(%T, %d)", state, id, state->fd);
@@ -1511,7 +1585,7 @@ erts_check_io_interrupt(ErtsPollThread *psi, int set)
 {
     if (psi) {
 #if ERTS_POLL_USE_FALLBACK
-        if (psi->ps == get_fallback()) {
+        if (psi->ps == get_fallback_pollset()) {
             erts_poll_interrupt_flbk(psi->ps, set);
             return;
         }
@@ -1527,7 +1601,7 @@ erts_create_pollset_thread(int id, ErtsThrPrgrData *tpd) {
 }
 
 void
-erts_check_io(ErtsPollThread *psi)
+erts_check_io(ErtsPollThread *psi, ErtsMonotonicTime timeout_time)
 {
     int pollres_len;
     int poll_ret, i;
@@ -1542,14 +1616,14 @@ erts_check_io(ErtsPollThread *psi)
     pollres_len = psi->pollres_len;
 
 #if ERTS_POLL_USE_FALLBACK
-    if (psi->ps == get_fallback()) {
+    if (psi->ps == get_fallback_pollset()) {
 
-        poll_ret = erts_poll_wait_flbk(psi->ps, psi->pollres, &pollres_len, psi->tpd);
+        poll_ret = erts_poll_wait_flbk(psi->ps, psi->pollres, &pollres_len, psi->tpd, timeout_time);
 
     } else
 #endif
     {
-        poll_ret = erts_poll_wait(psi->ps, psi->pollres, &pollres_len, psi->tpd);
+        poll_ret = erts_poll_wait(psi->ps, psi->pollres, &pollres_len, psi->tpd, timeout_time);
     }
 
 #ifdef ERTS_ENABLE_LOCK_CHECK
@@ -1585,7 +1659,12 @@ erts_check_io(ErtsPollThread *psi)
         ErtsNifSelectDataState *free_nif = NULL;
 	ErtsSysFdType fd = (ErtsSysFdType) ERTS_POLL_RES_GET_FD(&psi->pollres[i]);
 	ErtsDrvEventState *state;
-        ErtsPollEvents revents;
+        ErtsPollEvents revents = ERTS_POLL_RES_GET_EVTS(&psi->pollres[i]);
+
+        /* The fd will be set to -1 if a pollset internal fd was triggered
+           that was determined to be too expensive to remove from the result.
+        */
+        if (fd == -1) continue;
 
 	erts_mtx_lock(fd_mtx(fd));
 
@@ -1596,8 +1675,6 @@ erts_check_io(ErtsPollThread *psi)
             continue;
 	}
 
-        revents = ERTS_POLL_RES_GET_EVTS(&psi->pollres[i]);
-
         DEBUG_PRINT_FD("triggered %s", state, ev2str(revents));
 
         if (revents & ERTS_POLL_EV_ERR) {
@@ -1609,25 +1686,39 @@ erts_check_io(ErtsPollThread *psi)
              */
             revents = state->active_events;
             state->active_events = 0;
+
+            if (state->flags & ERTS_EV_FLAG_IN_SCHEDULER) {
+                erts_io_control(state, ERTS_POLL_OP_MOD, 0);
+                state->flags &= ~ERTS_EV_FLAG_IN_SCHEDULER;
+            }
         } else {
 
             /* Disregard any events that are not active at the moment,
                for instance this could happen if the driver/nif does
                select/deselect in rapid succession. */
             revents &= state->active_events | ERTS_POLL_EV_NVAL;
-            state->active_events &= ~revents;
 
-            /* Reactivate the poll op if there are still active events */
-            if (state->active_events) {
-                ErtsPollEvents new_events;
-                DEBUG_PRINT_FD("re-enable %s", state, ev2str(state->active_events));
+            if (psi->ps != get_scheduler_pollset(fd) || !ERTS_POLL_USE_SCHEDULER_POLLING) {
+                ErtsPollEvents reactive_events;
+                state->active_events &= ~revents;
+
+                reactive_events = state->active_events;
 
-                new_events = erts_io_control(state, ERTS_POLL_OP_MOD, state->active_events);
+                if (state->flags & ERTS_EV_FLAG_IN_SCHEDULER)
+                    reactive_events &= ~ERTS_POLL_EV_IN;
 
-                /* Unable to re-enable the fd, signal all callbacks */
-                if (new_events & (ERTS_POLL_EV_ERR|ERTS_POLL_EV_NVAL)) {
-                    revents |= state->active_events;
-                    state->active_events = 0;
+                /* Reactivate the poll op if there are still active events */
+                if (reactive_events) {
+                    ErtsPollEvents new_events;
+                    DEBUG_PRINT_FD("re-enable %s", state, ev2str(reactive_events));
+
+                    new_events = erts_io_control(state, ERTS_POLL_OP_MOD, reactive_events);
+
+                    /* Unable to re-enable the fd, signal all callbacks */
+                    if (new_events & (ERTS_POLL_EV_ERR|ERTS_POLL_EV_NVAL)) {
+                        revents |= reactive_events;
+                        state->active_events &= ~reactive_events;
+                    }
                 }
             }
         }
@@ -1703,7 +1794,7 @@ erts_check_io(ErtsPollThread *psi)
 
         case ERTS_EV_TYPE_STOP_USE: {
 #if ERTS_POLL_USE_FALLBACK
-            ASSERT(psi->ps == get_fallback());
+            ASSERT(psi->ps == get_fallback_pollset());
 #endif
             drv_ptr = state->driver.stop.drv_ptr;
             state->type = ERTS_EV_TYPE_NONE;
@@ -2041,12 +2132,17 @@ erts_init_check_io(int *argc, char **argv)
     for (j=0; j < erts_no_pollsets; j++)
         pollsetv[j] = erts_poll_create_pollset(j);
 
-#if ERTS_POLL_USE_FALLBACK
-    flbk_pollset = erts_poll_create_pollset_flbk(-1);
+    no_poll_threads = erts_no_poll_threads;
+
+    j = -1;
+
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    sched_pollset = erts_poll_create_pollset(j--);
+    no_poll_threads++;
 #endif
 
-    no_poll_threads = erts_no_poll_threads;
 #if ERTS_POLL_USE_FALLBACK
+    flbk_pollset = erts_poll_create_pollset_flbk(j--);
     no_poll_threads++;
 #endif
 
@@ -2056,7 +2152,15 @@ erts_init_check_io(int *argc, char **argv)
     psiv[0].pollres_len = ERTS_CHECK_IO_POLL_RES_LEN;
     psiv[0].pollres = erts_alloc(ERTS_ALC_T_POLLSET,
         sizeof(ErtsPollResFd) * ERTS_CHECK_IO_POLL_RES_LEN);
-    psiv[0].ps = get_fallback();
+    psiv[0].ps = get_fallback_pollset();
+    psiv++;
+#endif
+
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    psiv[0].pollres_len = ERTS_CHECK_IO_POLL_RES_LEN;
+    psiv[0].pollres = erts_alloc(ERTS_ALC_T_POLLSET,
+        sizeof(ErtsPollResFd) * ERTS_CHECK_IO_POLL_RES_LEN);
+    psiv[0].ps = get_scheduler_pollset(0);
     psiv++;
 #endif
 
@@ -2113,7 +2217,12 @@ erts_check_io_size(void)
     int i;
 
 #if ERTS_POLL_USE_FALLBACK
-    erts_poll_info(get_fallback(), &pi);
+    erts_poll_info(get_fallback_pollset(), &pi);
+    res += pi.memory_size;
+#endif
+
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    erts_poll_info(get_scheduler_pollset(0), &pi);
     res += pi.memory_size;
 #endif
 
@@ -2145,13 +2254,21 @@ erts_check_io_info(void *proc)
     Uint sz, *szp, *hp, **hpp;
     ErtsPollInfo *piv;
     Sint i, j = 0, len;
-    int no_pollsets = erts_no_pollsets + ERTS_POLL_USE_FALLBACK;
+    int no_pollsets = erts_no_pollsets + ERTS_POLL_USE_FALLBACK + ERTS_POLL_USE_SCHEDULER_POLLING;
     ERTS_CT_ASSERT(ERTS_POLL_USE_FALLBACK == 0 || ERTS_POLL_USE_FALLBACK == 1);
+    ERTS_CT_ASSERT(ERTS_POLL_USE_SCHEDULER_POLLING == 0 || ERTS_POLL_USE_SCHEDULER_POLLING == 1);
 
     piv = erts_alloc(ERTS_ALC_T_TMP, sizeof(ErtsPollInfo) * no_pollsets);
 
 #if ERTS_POLL_USE_FALLBACK
-    erts_poll_info_flbk(get_fallback(), &piv[0]);
+    erts_poll_info_flbk(get_fallback_pollset(), &piv[0]);
+    piv[0].poll_threads = 1;
+    piv[0].active_fds = 0;
+    piv++;
+#endif
+
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    erts_poll_info(get_scheduler_pollset(0), &piv[0]);
     piv[0].poll_threads = 1;
     piv[0].active_fds = 0;
     piv++;
@@ -2205,6 +2322,7 @@ erts_check_io_info(void *proc)
     sz = 0;
 
     piv -= ERTS_POLL_USE_FALLBACK;
+    piv -= ERTS_POLL_USE_SCHEDULER_POLLING;
 
  bld_it:
 
@@ -2309,15 +2427,7 @@ print_events(erts_dsprintf_buf_t *dsbufp, ErtsPollEvents ev)
 static ERTS_INLINE void
 print_flags(erts_dsprintf_buf_t *dsbufp, EventStateFlags f)
 {
-    const char* delim = "";
-    if(f & ERTS_EV_FLAG_USED) {
-	erts_dsprintf(dsbufp, "%s","USED");
-	delim = "|";
-    }
-    if(f & ERTS_EV_FLAG_FALLBACK) {
-	erts_dsprintf(dsbufp, "%s%s", delim, "FLBK");
-        delim = "|";
-    }
+    erts_dsprintf(dsbufp, "%s", flag2str(f));
 }
 
 #ifdef DEBUG_PRINT_MODE
@@ -2659,13 +2769,26 @@ erts_check_io_debug(ErtsCheckIoDebugInfo *ciodip)
 
 #if ERTS_POLL_USE_FALLBACK
     erts_dsprintf(dsbufp, "--- fds in flbk pollset ---------------------------------\n");
-    erts_poll_get_selected_events_flbk(get_fallback(), counters.epep,
+    erts_poll_get_selected_events_flbk(get_fallback_pollset(), counters.epep,
                                        drv_ev_state.max_fds);
     for (fd = 0; fd < len; fd++) {
         if (drv_ev_state.v[fd].flags & ERTS_EV_FLAG_FALLBACK)
             doit_erts_check_io_debug(&drv_ev_state.v[fd], &counters, dsbufp);
     }
 #endif
+#if ERTS_POLL_USE_SCHEDULER_POLLING
+    erts_dsprintf(dsbufp, "--- fds in scheduler pollset ----------------------------\n");
+    erts_poll_get_selected_events(get_scheduler_pollset(0), counters.epep,
+                                  drv_ev_state.max_fds);
+    for (fd = 0; fd < len; fd++) {
+        if (drv_ev_state.v[fd].flags & ERTS_EV_FLAG_SCHEDULER) {
+            if (drv_ev_state.v[fd].events && drv_ev_state.v[fd].events != ERTS_POLL_EV_NONE)
+                counters.epep[fd] &= ~ERTS_POLL_EV_OUT;
+            doit_erts_check_io_debug(&drv_ev_state.v[fd], &counters, dsbufp);
+        }
+    }
+#endif
+
     erts_dsprintf(dsbufp, "--- fds in pollset --------------------------------------\n");
 
     for (i = 0; i < erts_no_pollsets; i++) {
@@ -2674,8 +2797,15 @@ erts_check_io_debug(ErtsCheckIoDebugInfo *ciodip)
                                       drv_ev_state.max_fds);
         for (fd = 0; fd < len; fd++) {
             if (!(drv_ev_state.v[fd].flags & ERTS_EV_FLAG_FALLBACK)
-                && get_pollset_id(fd) == i)
+                && get_pollset_id(fd) == i) {
+                if (counters.epep[fd] != ERTS_POLL_EV_NONE &&
+                    drv_ev_state.v[fd].flags & ERTS_EV_FLAG_IN_SCHEDULER) {
+                    /* We add the in flag if it is enabled in the scheduler pollset
+                       and get_selected_events works on the platform */
+                    counters.epep[fd] |= ERTS_POLL_EV_IN;
+                }
                 doit_erts_check_io_debug(&drv_ev_state.v[fd], &counters, dsbufp);
+            }
         }
     }
     for (fd = len ; fd < drv_ev_state.max_fds; fd++) {
@@ -2722,7 +2852,7 @@ void erts_lcnt_update_cio_locks(int enable) {
 #endif
 
 #if ERTS_POLL_USE_FALLBACK
-    erts_lcnt_enable_pollset_lock_count_flbk(get_fallback(), enable);
+    erts_lcnt_enable_pollset_lock_count_flbk(get_fallback_pollset(), enable);
 #endif
 
     for (i = 0; i < erts_no_pollsets; i++)
diff --git a/erts/emulator/sys/common/erl_check_io.h b/erts/emulator/sys/common/erl_check_io.h
index 16aba8a5f3..31182be5ec 100644
--- a/erts/emulator/sys/common/erl_check_io.h
+++ b/erts/emulator/sys/common/erl_check_io.h
@@ -68,7 +68,7 @@ int erts_check_io_max_files(void);
  *
  * @param pt the poll thread structure to use.
  */
-void erts_check_io(struct erts_poll_thread *pt);
+void erts_check_io(struct erts_poll_thread *pt, ErtsMonotonicTime timeout_time);
 /**
  * Initialize the check io framework. This function will parse the arguments
  * and delete any entries that it is interested in.
@@ -129,16 +129,6 @@ extern int erts_no_poll_threads;
 #include "erl_poll.h"
 #include "erl_port_task.h"
 
-#ifdef __WIN32__
-/*
- * Current erts_poll implementation for Windows cannot handle
- * active events in the set of events polled.
- */
-#  define ERTS_CIO_DEFER_ACTIVE_EVENTS 1
-#else
-#  define ERTS_CIO_DEFER_ACTIVE_EVENTS 1
-#endif
-
 typedef struct {
     Eterm inport;
     Eterm outport;
@@ -150,10 +140,6 @@ struct erts_nif_select_event {
     Eterm pid;
     Eterm immed;
     Uint32 refn[ERTS_REF_NUMBERS];
-    Sint32 ddeselect_cnt; /* 0:  No delayed deselect in progress
-                           * 1:  Do deselect before next poll
-                           * >1: Countdown of ignored events
-                           */
 };
 
 typedef struct {
diff --git a/erts/emulator/sys/common/erl_poll.c b/erts/emulator/sys/common/erl_poll.c
index 5a5874ddfa..51d50933ff 100644
--- a/erts/emulator/sys/common/erl_poll.c
+++ b/erts/emulator/sys/common/erl_poll.c
@@ -121,7 +121,8 @@
 /* Define to print info about modifications done to each fd */
 #define DEBUG_PRINT_FD(FMT, PS, FD, ...) DEBUG_PRINT("%d: " FMT, PS, FD, ##__VA_ARGS__)
 /* Define to print entry and exit from erts_poll_wait (can be very spammy) */
-//#define DEBUG_PRINT_WAIT(FMT, PS, ...) DEBUG_PRINT(FMT, PS, ##__VA_ARGS__)
+// #define DEBUG_PRINT_WAIT(FMT, PS, ...) DEBUG_PRINT(FMT, PS, ##__VA_ARGS__)
+// #define DEBUG_PRINT_WAIT(FMT, PS, ...) do { if ((PS)->id != -1) DEBUG_PRINT(FMT, PS, ##__VA_ARGS__); } while(0)
 
 #else
 #define ERTS_POLL_DEBUG_PRINT 0
@@ -200,7 +201,7 @@ int ERTS_SELECT(int nfds, ERTS_fd_set *readfds, ERTS_fd_set *writefds,
 
 #define ERTS_POLL_USE_CONCURRENT_UPDATE (ERTS_POLL_USE_EPOLL || ERTS_POLL_USE_KQUEUE)
 
-#define ERTS_POLL_USE_WAKEUP_PIPE (!ERTS_POLL_USE_CONCURRENT_UPDATE)
+#define ERTS_POLL_USE_WAKEUP(ps) (!ERTS_POLL_USE_CONCURRENT_UPDATE || (ps)->id < 0)
 
 #if !ERTS_POLL_USE_CONCURRENT_UPDATE
 
@@ -269,6 +270,7 @@ struct ERTS_POLL_EXPORT(erts_pollset) {
 
 #if ERTS_POLL_USE_KERNEL_POLL
     int kp_fd;
+    int oneshot;
 #endif /* ERTS_POLL_USE_KERNEL_POLL */
 
 #if ERTS_POLL_USE_POLL
@@ -295,12 +297,16 @@ struct ERTS_POLL_EXPORT(erts_pollset) {
     ErtsPollSetUpdateRequestsBlock *curr_upd_req_block;
     erts_atomic32_t have_update_requests;
     erts_mtx_t mtx;
-    erts_atomic32_t wakeup_state;
+#else
+    int do_wakeup;
 #endif
 
-#if ERTS_POLL_USE_WAKEUP_PIPE
-    int wake_fds[2];
+#if ERTS_POLL_USE_TIMERFD
+    int timer_fd;
 #endif
+    ErtsMonotonicTime timeout_time;
+    erts_atomic32_t wakeup_state;
+    int wake_fds[2];
 };
 
 void erts_silence_warn_unused_result(long unused);
@@ -365,63 +371,47 @@ static void print_misc_debug_info(void);
 uint32_t epoll_events(int kp_fd, int fd);
 #endif
 
-
 #define ERTS_POLL_NOT_WOKEN	0
 #define ERTS_POLL_WOKEN		-1
 #define ERTS_POLL_WOKEN_INTR	1
 
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
 static ERTS_INLINE void
 reset_wakeup_state(ErtsPollSet *ps)
 {
     erts_atomic32_set_mb(&ps->wakeup_state, ERTS_POLL_NOT_WOKEN);
 }
-#endif
 
 static ERTS_INLINE int
 is_woken(ErtsPollSet *ps)
 {
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
     return erts_atomic32_read_acqb(&ps->wakeup_state) != ERTS_POLL_NOT_WOKEN;
-#else
-    return 0;
-#endif
 }
 
 static ERTS_INLINE int
 is_interrupted_reset(ErtsPollSet *ps)
 {
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
     return (erts_atomic32_xchg_acqb(&ps->wakeup_state, ERTS_POLL_NOT_WOKEN)
 	    == ERTS_POLL_WOKEN_INTR);
-#else
-    return 0;
-#endif
 }
 
 static ERTS_INLINE void
 woke_up(ErtsPollSet *ps)
 {
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
     erts_aint32_t wakeup_state = erts_atomic32_read_acqb(&ps->wakeup_state);
     if (wakeup_state == ERTS_POLL_NOT_WOKEN)
 	(void) erts_atomic32_cmpxchg_nob(&ps->wakeup_state,
 					 ERTS_POLL_WOKEN,
 					 ERTS_POLL_NOT_WOKEN);
     ASSERT(erts_atomic32_read_nob(&ps->wakeup_state) != ERTS_POLL_NOT_WOKEN);
-#endif
 }
 
 /*
  * --- Wakeup pipe -----------------------------------------------------------
  */
 
-#if ERTS_POLL_USE_WAKEUP_PIPE
-
 static ERTS_INLINE void
 wake_poller(ErtsPollSet *ps, int interrupted)
 {
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
     int wake;
     erts_aint32_t wakeup_state;
     if (!interrupted)
@@ -434,9 +424,9 @@ wake_poller(ErtsPollSet *ps, int interrupted)
     wake = wakeup_state == ERTS_POLL_NOT_WOKEN;
 
     if (wake)
-#endif
     {
 	ssize_t res;
+        DEBUG_PRINT_WAIT("wake_poller(%d)", ps, interrupted);
 	if (ps->wake_fds[1] < 0)
 	    return; /* Not initialized yet */
 	do {
@@ -474,10 +464,8 @@ cleanup_wakeup_pipe(ErtsPollSet *ps)
 		    fd,
 		    erl_errno_id(errno), errno);
     }
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
     if (intr)
 	erts_atomic32_set_nob(&ps->wakeup_state, ERTS_POLL_WOKEN_INTR);
-#endif
 }
 
 static void
@@ -513,7 +501,67 @@ create_wakeup_pipe(ErtsPollSet *ps)
     ps->wake_fds[1] = wake_fds[1];
 }
 
+/*
+ * --- timer fd -----------------------------------------------------------
+ */
+
+#if ERTS_POLL_USE_TIMERFD
+
+/* We use the timerfd when using epoll_wait to get high accuracy
+   timeouts, i.e. we want to sleep with < ms accuracy. */
+
+static void
+create_timerfd(ErtsPollSet *ps)
+{
+    int do_wake = 0;
+    int timer_fd = timerfd_create(CLOCK_MONOTONIC,0);
+    ERTS_POLL_EXPORT(erts_poll_control)(ps,
+					timer_fd,
+                                        ERTS_POLL_OP_ADD,
+					ERTS_POLL_EV_IN,
+                                        &do_wake);
+    if (ps->internal_fd_limit <= timer_fd)
+	ps->internal_fd_limit = timer_fd + 1;
+    ps->timer_fd = timer_fd;
+}
+
+static ERTS_INLINE void
+timerfd_set(ErtsPollSet *ps, struct itimerspec *its)
+{
+#ifdef DEBUG
+    struct itimerspec old_its;
+    int res;
+    res = timerfd_settime(ps->timer_fd, 0, its, &old_its);
+    ASSERT(res == 0);
+    ASSERT(old_its.it_interval.tv_sec == 0 &&
+           old_its.it_interval.tv_nsec == 0 &&
+           old_its.it_value.tv_sec == 0 &&
+           old_its.it_value.tv_nsec == 0);
+
+#else
+    timerfd_settime(ps->timer_fd, 0, its, NULL);
 #endif
+}
+
+static ERTS_INLINE int
+timerfd_clear(ErtsPollSet *ps, ErtsPollResFd pr[], int res, int max_res) {
+
+    struct itimerspec its;
+    /* we always have to clear the timer */
+    its.it_interval.tv_sec = 0;
+    its.it_interval.tv_nsec = 0;
+    its.it_value.tv_sec = 0;
+    its.it_value.tv_nsec = 0;
+    timerfd_settime(ps->timer_fd, 0, &its, NULL);
+
+    /* only timeout fd triggered */
+    if (res == 1 && pr[0].data.fd == ps->timer_fd)
+        return 0;
+
+    return res;
+}
+
+#endif /* ERTS_POLL_USE_TIMERFD */
 
 /*
  * --- Poll set update requests ----------------------------------------------
@@ -691,9 +739,12 @@ update_pollset(ErtsPollSet *ps, int fd, ErtsPollOp op, ErtsPollEvents events)
     struct epoll_event epe_templ;
     struct epoll_event epe;
 
-    epe_templ.events = ERTS_POLL_EV_E2N(events) | EPOLLONESHOT;
+    epe_templ.events = ERTS_POLL_EV_E2N(events);
     epe_templ.data.fd = fd;
 
+    if (ps->oneshot)
+        epe_templ.events |= EPOLLONESHOT;
+
 #ifdef VALGRIND
     /* Silence invalid valgrind warning ... */
     memset((void *) &epe.data, 0, sizeof(epoll_data_t));
@@ -802,6 +853,7 @@ update_pollset(ErtsPollSet *ps, int fd, ErtsPollOp op, ErtsPollEvents events)
     int res = 0, len = 0;
     struct kevent evts[2];
     struct timespec ts = {0, 0};
+    uint32_t oneshot = 0;
 
     if (op == ERTS_POLL_OP_ADD) {
         /* This is a hack to make the "noshell" option work; kqueue can poll
@@ -840,6 +892,9 @@ update_pollset(ErtsPollSet *ps, int fd, ErtsPollOp op, ErtsPollEvents events)
        man page), but it seems to be the way it works...
     */
 
+    if (ps->oneshot)
+        oneshot = EV_DISPATCH;
+
     if (op == ERTS_POLL_OP_DEL) {
         erts_atomic_dec_nob(&ps->no_of_user_fds);
         /* We could probably skip this delete, do we want to? */
@@ -849,27 +904,29 @@ update_pollset(ErtsPollSet *ps, int fd, ErtsPollOp op, ErtsPollEvents events)
         uint32_t flags;
         erts_atomic_inc_nob(&ps->no_of_user_fds);
 
-        flags = EV_ADD|EV_DISPATCH;
+        flags = EV_ADD|oneshot;
         flags |= ((events & ERTS_POLL_EV_IN) ? 0 : EV_DISABLE);
         ERTS_EV_SET(&evts[len++], fd, EVFILT_READ, flags, (void *) ERTS_POLL_EV_IN);
 
-        flags = EV_ADD|EV_DISPATCH;
+        flags = EV_ADD|oneshot;
         flags |= ((events & ERTS_POLL_EV_OUT) ? 0 : EV_DISABLE);
         ERTS_EV_SET(&evts[len++], fd, EVFILT_WRITE, flags, (void *) ERTS_POLL_EV_OUT);
     } else {
         uint32_t flags;
         ASSERT(op == ERTS_POLL_OP_MOD);
 
-        flags = EV_DISPATCH;
+        flags = oneshot;
         flags |= (events & ERTS_POLL_EV_IN) ? EV_ENABLE : EV_DISABLE;
         ERTS_EV_SET(&evts[len++], fd, EVFILT_READ, flags, (void *) ERTS_POLL_EV_IN);
 
-        flags = EV_DISPATCH;
+        flags = oneshot;
         flags |= (events & ERTS_POLL_EV_OUT) ? EV_ENABLE : EV_DISABLE;
         ERTS_EV_SET(&evts[len++], fd, EVFILT_WRITE, flags, (void *) ERTS_POLL_EV_OUT);
     }
 #else
-    uint32_t flags = EV_ADD|EV_ONESHOT;
+    uint32_t flags = EV_ADD;
+
+    if (ps->oneshot) flags |= EV_ONESHOT;
 
     if (op == ERTS_POLL_OP_DEL) {
         erts_atomic_dec_nob(&ps->no_of_user_fds);
@@ -903,14 +960,17 @@ update_pollset(ErtsPollSet *ps, int fd, ErtsPollOp op, ErtsPollEvents events)
         keventbp += sprintf(keventbp, "kevent(%d, {",ps->kp_fd);
         for (i = 0; i < len; i++) {
             const char *flags = "UNKNOWN";
-            if (evts[i].flags == EV_DELETE) flags = "EV_DELETE";
+            if (evts[i].flags == (EV_DELETE)) flags = "EV_DELETE";
             if (evts[i].flags == (EV_ADD|EV_ONESHOT)) flags = "EV_ADD|EV_ONESHOT";
+            if (evts[i].flags == (EV_ADD)) flags = "EV_ADD";
 #ifdef EV_DISPATCH
             if (evts[i].flags == (EV_ADD|EV_DISPATCH)) flags = "EV_ADD|EV_DISPATCH";
             if (evts[i].flags == (EV_ADD|EV_DISABLE)) flags = "EV_ADD|EV_DISABLE";
             if (evts[i].flags == (EV_ENABLE|EV_DISPATCH)) flags = "EV_ENABLE|EV_DISPATCH";
-            if (evts[i].flags == EV_DISABLE) flags = "EV_DISABLE";
+            if (evts[i].flags == (EV_ENABLE)) flags = "EV_ENABLE";
+            if (evts[i].flags == (EV_DISABLE)) flags = "EV_DISABLE";
             if (evts[i].flags == (EV_DISABLE|EV_DISPATCH)) flags = "EV_DISABLE|EV_DISABLE";
+            if (evts[i].flags == (EV_DISABLE)) flags = "EV_DISABLE";
 #endif
 
             keventbp += sprintf(keventbp, "%s{%lu, %s, %s}",i > 0 ? ", " : "",
@@ -1273,11 +1333,15 @@ poll_control(ErtsPollSet *ps, int fd, ErtsPollOp op,
 	    goto done;
 	}
 #endif
-#if ERTS_POLL_USE_WAKEUP_PIPE
 	if (fd == ps->wake_fds[0] || fd == ps->wake_fds[1]) {
 	    new_events = ERTS_POLL_EV_NVAL;
 	    goto done;
 	}
+#if ERTS_POLL_USE_TIMERFD
+        if (fd == ps->timer_fd) {
+	    new_events = ERTS_POLL_EV_NVAL;
+            goto done;
+        }
 #endif
     }
 
@@ -1333,11 +1397,8 @@ ERTS_POLL_EXPORT(erts_poll_control)(ErtsPollSet *ps,
 
     ERTS_POLLSET_UNLOCK(ps);
 
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
-    if (*do_wake) {
+    if (*do_wake)
 	wake_poller(ps, 0);
-    }
-#endif
 
     return res;
 }
@@ -1351,52 +1412,61 @@ ERTS_POLL_EXPORT(erts_poll_control)(ErtsPollSet *ps,
 static ERTS_INLINE int
 ERTS_POLL_EXPORT(save_result)(ErtsPollSet *ps, ErtsPollResFd pr[], int max_res, int chk_fds_res, int ebadf)
 {
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE || ERTS_POLL_DEBUG_PRINT || ERTS_POLL_USE_WAKEUP_PIPE
     int n = chk_fds_res < max_res ? chk_fds_res : max_res, i;
     int res = n;
-#if ERTS_POLL_USE_WAKEUP_PIPE
     int wake_fd = ps->wake_fds[0];
-#endif
 
-    for (i = 0; i < n; i++) {
-        int fd = ERTS_POLL_RES_GET_FD(&pr[i]);
-#ifdef DEBUG_PRINT_MODE
-        ErtsPollEvents evts = ERTS_POLL_RES_GET_EVTS(pr+i);
-#endif
+    if (ERTS_POLL_USE_WAKEUP(ps) || ERTS_POLL_DEBUG_PRINT || ERTS_POLL_USE_TIMERFD) {
 
-        DEBUG_PRINT_FD("trig %s (%s)", ps, fd,
-                       ev2str(evts),
+        for (i = 0; i < n; i++) {
+            int fd = ERTS_POLL_RES_GET_FD(&pr[i]);
+#if ERTS_POLL_DEBUG_PRINT
+            ErtsPollEvents evts = ERTS_POLL_RES_GET_EVTS(pr+i);
+
+            if (fd != wake_fd
+#if ERTS_POLL_USE_TIMERFD
+                && fd != ps->timer_fd
+#endif
+                )
+                DEBUG_PRINT_FD("trig %s (%s)", ps, fd,
+                               ev2str(evts),
 #if ERTS_POLL_USE_KQUEUE
-                       "kqueue"
+                               "kqueue"
 #elif ERTS_POLL_USE_EPOLL
-                       "epoll"
+                               "epoll"
 #else
-                       "/dev/poll"
+                               "/dev/poll"
+#endif
+                    );
 #endif
-            );
 
-#if ERTS_POLL_USE_WAKEUP_PIPE
-        if (fd == wake_fd) {
-            cleanup_wakeup_pipe(ps);
-            ERTS_POLL_RES_SET_EVTS(&pr[i], ERTS_POLL_EV_NONE);
-            if (n == 1)
-                return 0;
-        }
+            if (ERTS_POLL_USE_WAKEUP(ps) && fd == wake_fd) {
+                cleanup_wakeup_pipe(ps);
+                ERTS_POLL_RES_SET_FD(&pr[i], -1);
+                ERTS_POLL_RES_SET_EVTS(&pr[i], ERTS_POLL_EV_NONE);
+                res--;
+            }
+#if ERTS_POLL_USE_TIMERFD
+            else if (fd == ps->timer_fd) {
+                ERTS_POLL_RES_SET_FD(&pr[i], -1);
+                ERTS_POLL_RES_SET_EVTS(&pr[i], ERTS_POLL_EV_NONE);
+                res--;
+            }
 #endif
 #if !ERTS_POLL_USE_CONCURRENT_UPDATE
-        else {
-            /* Reset the events to emulate ONESHOT semantics */
-            ps->fds_status[fd].events = 0;
-            enqueue_update_request(ps, fd);
-        }
+            else {
+                /* Reset the events to emulate ONESHOT semantics */
+                ps->fds_status[fd].events = 0;
+                enqueue_update_request(ps, fd);
+            }
 #endif
+        }
     }
 
-    return res;
-#else
-    ASSERT(chk_fds_res <= max_res);
-    return chk_fds_res;
-#endif
+    if (res == 0)
+        return res;
+    else
+        return n;
 }
 
 #else /* !ERTS_POLL_USE_KERNEL_POLL */
@@ -1577,19 +1647,168 @@ ERTS_POLL_EXPORT(save_result)(ErtsPollSet *ps, ErtsPollResFd pr[], int max_res,
 
 #endif /* !ERTS_POLL_USE_KERNEL_POLL */
 
+static ERTS_INLINE ErtsMonotonicTime
+get_timeout(ErtsPollSet *ps,
+	    int resolution,
+	    ErtsMonotonicTime timeout_time)
+{
+    ErtsMonotonicTime timeout;
+
+    if (timeout_time == ERTS_POLL_NO_TIMEOUT) {
+	timeout = 0;
+    }
+    else if (timeout_time == ERTS_POLL_INF_TIMEOUT) {
+        timeout = -1;
+    }
+    else {
+	ErtsMonotonicTime diff_time, current_time;
+	current_time = erts_get_monotonic_time(NULL);
+	diff_time = timeout_time - current_time;
+	if (diff_time <= 0) {
+	    timeout = 0;
+	}
+	else {
+	    switch (resolution) {
+	    case 1000:
+		/* Round up to nearest even milli second */
+		timeout = ERTS_MONOTONIC_TO_MSEC(diff_time - 1) + 1;
+		if (timeout > (ErtsMonotonicTime) INT_MAX)
+		    timeout = (ErtsMonotonicTime) INT_MAX;
+		timeout -= ERTS_PREMATURE_TIMEOUT(timeout, 1000);
+		break;
+	    case 1000000:
+		/* Round up to nearest even micro second */
+		timeout = ERTS_MONOTONIC_TO_USEC(diff_time - 1) + 1;
+		timeout -= ERTS_PREMATURE_TIMEOUT(timeout, 1000*1000);
+		break;
+	    case 1000000000:
+		/* Round up to nearest even nano second */
+		timeout = ERTS_MONOTONIC_TO_NSEC(diff_time - 1) + 1;
+		timeout -= ERTS_PREMATURE_TIMEOUT(timeout, 1000*1000*1000);
+		break;
+	    default:
+		ERTS_INTERNAL_ERROR("Invalid resolution");
+		timeout = 0;
+		break;
+	    }
+	}
+    }
+    return timeout;
+}
+
+#if ERTS_POLL_USE_SELECT
+
+static ERTS_INLINE int
+get_timeout_timeval(ErtsPollSet *ps,
+		    SysTimeval *tvp,
+		    ErtsMonotonicTime timeout_time)
+{
+    ErtsMonotonicTime timeout = get_timeout(ps,
+					    1000*1000,
+					    timeout_time);
+
+    if (!timeout) {
+	tvp->tv_sec = 0;
+	tvp->tv_usec = 0;
+
+	return 0;
+    }
+    else if (timeout == -1) {
+        return -1;
+    }
+    else {
+	ErtsMonotonicTime sec = timeout/(1000*1000);
+	tvp->tv_sec = sec;
+	tvp->tv_usec = timeout - sec*(1000*1000);
+
+	ASSERT(tvp->tv_sec >= 0);
+	ASSERT(tvp->tv_usec >= 0);
+	ASSERT(tvp->tv_usec < 1000*1000);
+
+	return 1;
+    }
+
+}
+
+#endif
+
+#if ERTS_POLL_USE_KQUEUE || (ERTS_POLL_USE_POLL && defined(HAVE_PPOLL)) || ERTS_POLL_USE_TIMERFD
+
 static ERTS_INLINE int
-check_fd_events(ErtsPollSet *ps, ErtsPollResFd pr[], int do_wait, int max_res)
+get_timeout_timespec(ErtsPollSet *ps,
+		     struct timespec *tsp,
+		     ErtsMonotonicTime timeout_time)
+{
+    ErtsMonotonicTime timeout = get_timeout(ps,
+					    1000*1000*1000,
+					    timeout_time);
+
+    if (!timeout) {
+	tsp->tv_sec = 0;
+	tsp->tv_nsec = 0;
+	return 0;
+    }
+    else if (timeout == -1) {
+        return -1;
+    }
+    else {
+	ErtsMonotonicTime sec = timeout/(1000*1000*1000);
+	tsp->tv_sec = sec;
+	tsp->tv_nsec = timeout - sec*(1000*1000*1000);
+
+	ASSERT(tsp->tv_sec >= 0);
+	ASSERT(tsp->tv_nsec >= 0);
+	ASSERT(tsp->tv_nsec < 1000*1000*1000);
+
+	return 1;
+    }
+}
+
+#endif
+
+#if ERTS_POLL_USE_TIMERFD
+
+static ERTS_INLINE int
+get_timeout_itimerspec(ErtsPollSet *ps,
+                       struct itimerspec *itsp,
+                       ErtsMonotonicTime timeout_time)
+{
+
+    itsp->it_interval.tv_sec = 0;
+    itsp->it_interval.tv_nsec = 0;
+
+    return get_timeout_timespec(ps, &itsp->it_value, timeout_time);
+}
+ 
+#endif
+
+static ERTS_INLINE int
+check_fd_events(ErtsPollSet *ps, ErtsPollResFd pr[], int max_res, ErtsMonotonicTime timeout_time)
 {
     int res;
-    int timeout = do_wait ? -1 : 0;
-    DEBUG_PRINT_WAIT("Entering check_fd_events(), do_wait=%d", ps, do_wait);
+    int timeout;
+    DEBUG_PRINT_WAIT("Entering check_fd_events(), timeout=%d", ps, timeout_time);
     {
 #if ERTS_POLL_USE_EPOLL                /* --- epoll ------------------------------- */
+#if ERTS_POLL_USE_TIMERFD
+        struct itimerspec its;
+        timeout = get_timeout_itimerspec(ps, &its, timeout_time);
+        if (timeout > 0) {
+            timerfd_set(ps, &its);
+            res = epoll_wait(ps->kp_fd, pr, max_res, -1);
+            res = timerfd_clear(ps, pr, res, max_res);
+        } else {
+            res = epoll_wait(ps->kp_fd, pr, max_res, timeout);
+        }
+#else /* !ERTS_POLL_USE_TIMERFD */
+        timeout = (int) get_timeout(ps, 1000, timeout_time);
         res = epoll_wait(ps->kp_fd, pr, max_res, timeout);
-
+#endif /* !ERTS_POLL_USE_TIMERFD */
 #elif ERTS_POLL_USE_KQUEUE     /* --- kqueue ------------------------------ */
-        struct timespec ts = {0, 0};
-        struct timespec *tsp = timeout ? NULL : &ts;
+        struct timespec ts;
+        struct timespec *tsp;
+        timeout = get_timeout_timespec(ps, &ts, timeout_time);
+        tsp = timeout < 0 ? NULL : &ts;
         res = kevent(ps->kp_fd, NULL, 0, pr, max_res, tsp);
 #elif ERTS_POLL_USE_DEVPOLL	/* --- devpoll ----------------------------- */
         /*
@@ -1601,16 +1820,22 @@ check_fd_events(ErtsPollSet *ps, ErtsPollResFd pr[], int do_wait, int max_res)
         int nfds = (int) erts_atomic_read_nob(&ps->no_of_user_fds) + 1 /* wakeup pipe */;
         poll_res.dp_nfds = nfds < max_res ? nfds : max_res;
         poll_res.dp_fds = pr;
-        poll_res.dp_timeout = timeout;
+        poll_res.dp_timeout = (int) get_timeout(ps, 1000, timeout_time);
         res = ioctl(ps->kp_fd, DP_POLL, &poll_res);
-
+#elif ERTS_POLL_USE_POLL && defined(HAVE_PPOLL)	/* --- ppoll ---------------- */
+        struct timespec ts;
+        struct timespec *tsp = &ts;
+        timeout = get_timeout_timespec(ps, &ts, timeout_time);
+        if (timeout < 0) tsp = NULL;
+        res = ppoll(ps->poll_fds, ps->no_poll_fds, tsp, NULL);
 #elif ERTS_POLL_USE_POLL        /* --- poll --------------------------------- */
-
+        timeout = (int) get_timeout(ps, 1000, timeout_time);
         res = poll(ps->poll_fds, ps->no_poll_fds, timeout);
-
 #elif ERTS_POLL_USE_SELECT	/* --- select ------------------------------ */
-        SysTimeval tv = {0, 0};
-        SysTimeval *tvp = timeout ? NULL : &tv;
+        SysTimeval tv;
+        SysTimeval *tvp;
+        timeout = get_timeout_timeval(ps, &tv, timeout_time);
+        tvp = timeout < 0 ? NULL : &tv;
 
         ERTS_FD_COPY(&ps->input_fds, &ps->res_input_fds);
         ERTS_FD_COPY(&ps->output_fds, &ps->res_output_fds);
@@ -1630,7 +1855,8 @@ int
 ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet *ps,
 				 ErtsPollResFd pr[],
 				 int *len,
-                                 ErtsThrPrgrData *tpd)
+                                 ErtsThrPrgrData *tpd,
+                                 ErtsMonotonicTime timeout_time)
 {
     int res, no_fds, used_fds = 0;
     int ebadf = 0;
@@ -1655,53 +1881,56 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet *ps,
     }
 #endif
 
-    do_wait = !is_woken(ps) && used_fds == 0;
+    do_wait = !is_woken(ps) && used_fds == 0 && timeout_time != ERTS_POLL_NO_TIMEOUT;
 
     DEBUG_PRINT_WAIT("Entering %s(), do_wait=%d", ps, __FUNCTION__, do_wait);
 
     if (do_wait) {
+        tpd = tpd ? tpd : erts_thr_prgr_data(NULL);
         erts_thr_progress_prepare_wait(tpd);
         ERTS_MSACC_SET_STATE_CACHED(ERTS_MSACC_STATE_SLEEP);
-    }
+    } else
+        timeout_time = ERTS_POLL_NO_TIMEOUT;
 
     while (1) {
-	res = check_fd_events(ps, pr + used_fds, do_wait, no_fds - used_fds);
+        res = check_fd_events(ps, pr + used_fds, no_fds - used_fds, timeout_time);
+        if (res != 0)
+            break;
+        if (timeout_time == ERTS_POLL_NO_TIMEOUT)
+            break;
+        if (erts_get_monotonic_time(NULL) >= timeout_time)
+	    break;
+    }
 
 #if !ERTS_POLL_USE_CONCURRENT_UPDATE
-        if (res < 0
-            && errno == EBADF
-            && ERTS_POLLSET_HAVE_UPDATE_REQUESTS(ps)) {
-            /*
-             * This may have happened because another thread deselected
-             * a fd in our poll set and then closed it, i.e. the driver
-             * behaved correctly. We wan't to avoid looking for a bad
-             * fd, that may even not exist anymore. Therefore, handle
-             * update requests and try again. This behaviour should only
-             * happen when using SELECT as the polling mechanism.
-             */
-            ERTS_POLLSET_LOCK(ps);
-            used_fds += handle_update_requests(ps, pr + used_fds, no_fds - used_fds);
-            if (used_fds == no_fds) {
-                *len = used_fds;
-                ERTS_POLLSET_UNLOCK(ps);
-                return 0;
-            }
-            res = check_fd_events(ps, pr + used_fds, 0, no_fds - used_fds);
-            /* Keep the lock over the non-blocking poll in order to not
-               get any nasty races happening. */
+    if (res < 0
+        && errno == EBADF
+        && ERTS_POLLSET_HAVE_UPDATE_REQUESTS(ps)) {
+        /*
+         * This may have happened because another thread deselected
+         * a fd in our poll set and then closed it, i.e. the driver
+         * behaved correctly. We wan't to avoid looking for a bad
+         * fd, that may even not exist anymore. Therefore, handle
+         * update requests and try again. This behaviour should only
+         * happen when using SELECT as the polling mechanism.
+         */
+        ERTS_POLLSET_LOCK(ps);
+        used_fds += handle_update_requests(ps, pr + used_fds, no_fds - used_fds);
+        if (used_fds == no_fds) {
+            *len = used_fds;
             ERTS_POLLSET_UNLOCK(ps);
-            if (res == 0) {
-                errno = EAGAIN;
-                res = -1;
-            }
+            return 0;
+        }
+        res = check_fd_events(ps, pr + used_fds, no_fds - used_fds, ERTS_POLL_NO_TIMEOUT);
+        /* Keep the lock over the non-blocking poll in order to not
+           get any nasty races happening. */
+        ERTS_POLLSET_UNLOCK(ps);
+        if (res == 0) {
+            errno = EAGAIN;
+            res = -1;
         }
-#endif
-
-	if (res != 0)
-	    break;
-        if (!do_wait)
-            break;
     }
+#endif
 
     if (do_wait) {
         erts_thr_progress_finalize_wait(tpd);
@@ -1709,7 +1938,8 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet *ps,
         ERTS_MSACC_SET_STATE_CACHED(ERTS_MSACC_STATE_CHECK_IO);
     }
 
-    woke_up(ps);
+    if (ERTS_POLL_USE_WAKEUP(ps))
+        woke_up(ps);
 
     if (res < 0) {
 #if ERTS_POLL_USE_SELECT
@@ -1720,11 +1950,16 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet *ps,
 #endif
 	res = errno;
     }
-    else {
+    else if (res == 0) {
+        res = used_fds == 0 ? ETIMEDOUT : 0;
+#ifdef HARD_DEBUG
+	check_poll_result(pr, used_fds);
+#endif
+        *len = used_fds;
+    } else {
 #if ERTS_POLL_USE_SELECT
     save_results:
 #endif
-
 	ps_locked = 1;
 	ERTS_POLLSET_LOCK(ps);
 
@@ -1754,12 +1989,13 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet *ps,
 void
 ERTS_POLL_EXPORT(erts_poll_interrupt)(ErtsPollSet *ps, int set)
 {
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
-    if (!set)
-	reset_wakeup_state(ps);
-    else
-	wake_poller(ps, 1);
-#endif
+    DEBUG_PRINT_WAIT("poll_interrupt(%d)", ps, set);
+    if (ERTS_POLL_USE_WAKEUP(ps)) {
+        if (!set)
+            reset_wakeup_state(ps);
+        else
+            wake_poller(ps, 1);
+    }
 }
 
 int
@@ -1875,10 +2111,20 @@ ERTS_POLL_EXPORT(erts_poll_create_pollset)(int id)
     if (ps->internal_fd_limit <= kp_fd)
 	ps->internal_fd_limit = kp_fd + 1;
     ps->kp_fd = kp_fd;
+    if (ps->id == -1)
+        ps->oneshot = 0;
+    else
+        ps->oneshot = 1;
 #endif
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
+
     erts_atomic32_init_nob(&ps->wakeup_state, (erts_aint32_t) 0);
     create_wakeup_pipe(ps);
+
+#if ERTS_POLL_USE_TIMERFD
+    create_timerfd(ps);
+#endif
+
+#if !ERTS_POLL_USE_CONCURRENT_UPDATE
     handle_update_requests(ps, NULL, 0);
     cleanup_wakeup_pipe(ps);
 #endif
@@ -1993,9 +2239,7 @@ ERTS_POLL_EXPORT(erts_poll_info)(ErtsPollSet *ps, ErtsPollInfo *pip)
     pip->memory_size = size;
 
     pip->poll_set_size = (int) erts_atomic_read_nob(&ps->no_of_user_fds);
-#if !ERTS_POLL_USE_CONCURRENT_UPDATE
     pip->poll_set_size++; /* Wakeup pipe */
-#endif
 
     pip->lazy_updates =
 #if !ERTS_POLL_USE_CONCURRENT_UPDATE
@@ -2178,6 +2422,12 @@ ERTS_POLL_EXPORT(erts_poll_get_selected_events)(ErtsPollSet *ps,
             ASSERT(0);
             return;
         }
+        if (fd == ps->wake_fds[0] || fd == ps->wake_fds[1])
+            continue;
+#if ERTS_POLL_USE_TIMERFD
+        if (fd == ps->timer_fd)
+            continue;
+#endif
         data &= 0xFFFFFFFF;
         ASSERT(fd == data);
         /* Events are the events that are being monitored, which of course include
diff --git a/erts/emulator/sys/common/erl_poll.h b/erts/emulator/sys/common/erl_poll.h
index e1cea7eb8b..d40dabc529 100644
--- a/erts/emulator/sys/common/erl_poll.h
+++ b/erts/emulator/sys/common/erl_poll.h
@@ -51,6 +51,7 @@
 #include "sys.h"
 
 #define ERTS_POLL_NO_TIMEOUT ERTS_MONOTONIC_TIME_MIN
+#define ERTS_POLL_INF_TIMEOUT ERTS_MONOTONIC_TIME_MAX
 
 #ifdef ERTS_ENABLE_KERNEL_POLL
 #  undef ERTS_ENABLE_KERNEL_POLL
@@ -130,6 +131,9 @@
 #endif
 
 #define ERTS_POLL_USE_FALLBACK (ERTS_POLL_USE_KQUEUE || ERTS_POLL_USE_EPOLL)
+#define ERTS_POLL_USE_SCHEDULER_POLLING (ERTS_POLL_USE_KQUEUE || ERTS_POLL_USE_EPOLL)
+#define ERTS_POLL_SCHEDULER_POLLING_TIMEOUT 10
+#define ERTS_POLL_USE_TIMERFD 0
 
 typedef Uint32 ErtsPollEvents;
 
@@ -156,6 +160,14 @@ typedef enum {
 
 #include <sys/epoll.h>
 
+#if ERTS_POLL_USE_EPOLL
+#ifdef HAVE_SYS_TIMERFD_H
+#include <sys/timerfd.h>
+#undef ERTS_POLL_USE_TIMERFD
+#define ERTS_POLL_USE_TIMERFD 1
+#endif
+#endif
+
 #define ERTS_POLL_EV_E2N(EV) \
   ((uint32_t) (EV))
 #define ERTS_POLL_EV_N2E(EV) \
@@ -276,7 +288,7 @@ typedef struct _ErtsPollResFd {
 
 #endif
 
-#define ERTS_POLL_EV_NONE (UINT_MAX & ~(ERTS_POLL_EV_IN|ERTS_POLL_EV_OUT|ERTS_POLL_EV_NVAL|ERTS_POLL_EV_ERR))
+#define ERTS_POLL_EV_NONE ERTS_POLL_EV_N2E((UINT_MAX & ~(ERTS_POLL_EV_IN|ERTS_POLL_EV_OUT|ERTS_POLL_EV_NVAL|ERTS_POLL_EV_ERR)))
 
 #define ev2str(ev)                                                     \
     (((ev) == 0 || (ev) == ERTS_POLL_EV_NONE) ? "NONE" :               \
diff --git a/erts/emulator/sys/common/erl_poll_api.h b/erts/emulator/sys/common/erl_poll_api.h
index f35f64a9f3..f3a91e54f7 100644
--- a/erts/emulator/sys/common/erl_poll_api.h
+++ b/erts/emulator/sys/common/erl_poll_api.h
@@ -73,12 +73,14 @@ ErtsPollEvents ERTS_POLL_EXPORT(erts_poll_control)(ErtsPollSet *ps,
  * @param[in] length the length of the res array
  * @param[out] length the number of ready events returned in res
  * @param tpd the thread progress data to note sleep state in
+ * @param timeout_time the time in native to wake up at
  * @return 0 on success, else the ERRNO of the error that happened.
  */
 int ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet *ps,
                                      ErtsPollResFd res[],
                                      int *length,
-                                     ErtsThrPrgrData *tpd);
+                                     ErtsThrPrgrData *tpd,
+                                     ErtsMonotonicTime timeout_time);
 /**
  * Interrupt the thread waiting in the pollset. This function should be called
  * with set = 0 before any thread calls erts_poll_wait in order to clear any
diff --git a/erts/emulator/sys/win32/erl_poll.c b/erts/emulator/sys/win32/erl_poll.c
index 5d832f4d34..3843a27a6e 100644
--- a/erts/emulator/sys/win32/erl_poll.c
+++ b/erts/emulator/sys/win32/erl_poll.c
@@ -1018,10 +1018,11 @@ ErtsPollEvents erts_poll_control(ErtsPollSet *ps,
 int erts_poll_wait(ErtsPollSet *ps,
 		   ErtsPollResFd pr[],
 		   int *len,
-                   ErtsThrPrgrData *tpd)
+                   ErtsThrPrgrData *tpd,
+                   Sint64 timeout_in)
 {
     int no_fds;
-    DWORD timeout = INFINITE;
+    DWORD timeout = timeout_in == -1 ? INFINITE : timeout_in;
     EventData* ev;
     int res = 0;
     int num = 0;
diff --git a/erts/emulator/test/scheduler_SUITE.erl b/erts/emulator/test/scheduler_SUITE.erl
index f04efb9003..2e0dfa42f3 100644
--- a/erts/emulator/test/scheduler_SUITE.erl
+++ b/erts/emulator/test/scheduler_SUITE.erl
@@ -1450,26 +1450,29 @@ poll_threads(Config) when is_list(Config) ->
     {Conc, PollType, KP} = get_ioconfig(Config),
     {Sched, SchedOnln, _} = get_sstate(Config, ""),
 
-    [1, 1] = get_ionum(Config,"+IOt 2 +IOp 2"),
-    [1, 1, 1, 1, 1] = get_ionum(Config,"+IOt 5 +IOp 5"),
-
-    [1, 1] = get_ionum(Config, "+S 2 +IOPt 100 +IOPp 100"),
-
     if
         Conc ->
-            [5] = get_ionum(Config,"+IOt 5 +IOp 1"),
-            [3, 2] = get_ionum(Config,"+IOt 5 +IOp 2"),
-            [2, 2, 2, 2, 2] = get_ionum(Config,"+IOt 10 +IOPp 50"),
+            [1, 1, 1] = get_ionum(Config,"+IOt 2 +IOp 2"),
+            [1, 1, 1, 1, 1, 1] = get_ionum(Config,"+IOt 5 +IOp 5"),
+            [1, 1, 1] = get_ionum(Config, "+S 2 +IOPt 100 +IOPp 100"),
 
-            [2] = get_ionum(Config, "+S 2 +IOPt 100"),
-            [4] = get_ionum(Config, "+S 4 +IOPt 100"),
-            [4] = get_ionum(Config, "+S 4:2 +IOPt 100"),
-            [4, 4] = get_ionum(Config, "+S 8 +IOPt 100 +IOPp 25"),
+            [5, 1] = get_ionum(Config,"+IOt 5 +IOp 1"),
+            [3, 2, 1] = get_ionum(Config,"+IOt 5 +IOp 2"),
+            [2, 2, 2, 2, 2, 1] = get_ionum(Config,"+IOt 10 +IOPp 50"),
+
+            [2, 1] = get_ionum(Config, "+S 2 +IOPt 100"),
+            [4, 1] = get_ionum(Config, "+S 4 +IOPt 100"),
+            [4, 1] = get_ionum(Config, "+S 4:2 +IOPt 100"),
+            [4, 4, 1] = get_ionum(Config, "+S 8 +IOPt 100 +IOPp 25"),
 
             fail = get_ionum(Config, "+IOt 1 +IOp 2"),
 
             ok;
         not Conc ->
+            [1, 1] = get_ionum(Config,"+IOt 2 +IOp 2"),
+            [1, 1, 1, 1, 1] = get_ionum(Config,"+IOt 5 +IOp 5"),
+            [1, 1] = get_ionum(Config, "+S 2 +IOPt 100 +IOPp 100"),
+
             [1, 1, 1, 1, 1] = get_ionum(Config,"+IOt 5 +IOp 1"),
             [1, 1, 1, 1, 1] = get_ionum(Config,"+IOt 5 +IOp 2"),
             [1, 1, 1, 1, 1, 1, 1, 1, 1, 1] = get_ionum(Config,"+IOt 10 +IOPp 50"),
diff --git a/erts/emulator/test/signal_SUITE.erl b/erts/emulator/test/signal_SUITE.erl
index fab2f45f28..4e6baa9e0e 100644
--- a/erts/emulator/test/signal_SUITE.erl
+++ b/erts/emulator/test/signal_SUITE.erl
@@ -85,7 +85,7 @@ xm_sig_order_proc() ->
     receive
 	may_not_reach -> exit(bad_signal_order);
 	may_reach -> ok
-    after 0 -> ok
+    after 0 -> erlang:yield()
     end,
     xm_sig_order_proc().