Merge branch 'rickard/timer-optimization/OTP-12650'

* rickard/timer-optimization/OTP-12650:
  Timer fixes, documentation, and test cases

Conflicts:
	erts/emulator/beam/erl_hl_timer.c

3 files changed, 79 insertions, 63 deletions

diff --git a/erts/emulator/beam/erl_alloc.c b/erts/emulator/beam/erl_alloc.c
index b832626e7b..dcae5509ec 100644
--- a/erts/emulator/beam/erl_alloc.c
+++ b/erts/emulator/beam/erl_alloc.c
@@ -2331,6 +2331,22 @@ erts_memory(int *print_to_p, void *print_to_arg, void *proc, Eterm earg)
 		       &size.processes_used,
 		       fi,
 		       ERTS_ALC_T_MSG_REF);
+	add_fix_values(&size.processes,
+		       &size.processes_used,
+		       fi,
+		       ERTS_ALC_T_LL_PTIMER);
+	add_fix_values(&size.processes,
+		       &size.processes_used,
+		       fi,
+		       ERTS_ALC_T_HL_PTIMER);
+	add_fix_values(&size.processes,
+		       &size.processes_used,
+		       fi,
+		       ERTS_ALC_T_BIF_TIMER);
+	add_fix_values(&size.processes,
+		       &size.processes_used,
+		       fi,
+		       ERTS_ALC_T_ABIF_TIMER);
     }
 
     if (want.atom || want.atom_used) {
diff --git a/erts/emulator/beam/erl_hl_timer.c b/erts/emulator/beam/erl_hl_timer.c
index cf92ded415..51cd843935 100644
--- a/erts/emulator/beam/erl_hl_timer.c
+++ b/erts/emulator/beam/erl_hl_timer.c
@@ -850,8 +850,6 @@ hl_timer_destroy(ErtsHLTimer *tmr)
     if (!(roflgs & ERTS_TMR_ROFLG_BIF_TMR))
 	erts_free(ERTS_ALC_T_HL_PTIMER, tmr);
     else {
-	if (tmr->btm.bp)
-	    free_message_buffer(tmr->btm.bp);
 	if (roflgs & ERTS_TMR_ROFLG_PRE_ALC)
 	    bif_timer_pre_free(tmr);
 	else if (roflgs & ERTS_TMR_ROFLG_ABIF_TMR)
@@ -898,10 +896,6 @@ schedule_hl_timer_destroy(ErtsHLTimer *tmr, Uint32 roflgs)
 	 * Message buffer can be dropped at
 	 * once...
 	 */
-	if (tmr->btm.bp) {
-	    free_message_buffer(tmr->btm.bp);
-	    tmr->btm.bp = NULL;
-	}
 	size = sizeof(ErtsHLTimer);
     }
 
@@ -1121,6 +1115,7 @@ hlt_bif_timer_timeout(ErtsHLTimer *tmr, Uint32 roflgs)
 {
     ErtsProcLocks proc_locks = ERTS_PROC_LOCKS_MSG_SEND;
     Process *proc;
+    int queued_message = 0;
     int dec_refc = 0;
     Uint32 is_reg_name = (roflgs & ERTS_TMR_ROFLG_REG_NAME);
     ERTS_HLT_ASSERT(roflgs & ERTS_TMR_ROFLG_BIF_TMR);
@@ -1152,6 +1147,7 @@ hlt_bif_timer_timeout(ErtsHLTimer *tmr, Uint32 roflgs)
 	    erts_queue_message(proc, &proc_locks, tmr->btm.bp,
 			       tmr->btm.message, NIL);
 	    erts_smp_proc_unlock(proc, ERTS_PROC_LOCKS_MSG_SEND);
+	    queued_message = 1;
 	    proc_locks &= ~ERTS_PROC_LOCKS_MSG_SEND;
 	    tmr->btm.bp = NULL;
 	    if (tmr->btm.proc_tree.parent != ERTS_HLT_PFIELD_NOT_IN_TABLE) {
@@ -1165,6 +1161,8 @@ hlt_bif_timer_timeout(ErtsHLTimer *tmr, Uint32 roflgs)
 	if (dec_refc)
 	    hl_timer_pre_dec_refc(tmr);
     }
+    if (!queued_message && tmr->btm.bp)
+	free_message_buffer(tmr->btm.bp);
 }
 
 static ERTS_INLINE void
@@ -1682,6 +1680,8 @@ setup_bif_timer(Process *c_p, ErtsMonotonicTime timeout_pos,
 					  rcvr, ERTS_PROC_LOCK_BTM,
 					  ERTS_P2P_FLG_INC_REFC);
 	if (!proc) {
+	    if (tmr->btm.bp)
+		free_message_buffer(tmr->btm.bp);
 	    hlt_delete_timer(esdp, tmr);
 	    hl_timer_destroy(tmr);
 	}
@@ -1714,6 +1714,9 @@ cancel_bif_timer(ErtsHLTimer *tmr)
     if (state != ERTS_TMR_STATE_ACTIVE)
 	return 0;
 
+    if (tmr->btm.bp)
+	free_message_buffer(tmr->btm.bp);
+
     res = -1;
 
     roflgs = tmr->head.roflgs;
@@ -1827,18 +1830,25 @@ access_sched_local_btm(Process *c_p, Eterm pid,
 	if (!async)
 	    hsz += REF_THING_SIZE;
 	else {
-	    if (is_non_value(tref))
+	    if (is_non_value(tref) || proc != c_p)
 		hsz += REF_THING_SIZE;
 	    hsz += 1; /* upgrade to 3-tuple */
 	}
 	if (time_left > (Sint64) MAX_SMALL)
 	    hsz += ERTS_SINT64_HEAP_SIZE(time_left);
 
-	hp = erts_alloc_message_heap(hsz,
-				     &bp,
-				     &ohp,
-				     proc,
-				     &proc_locks);
+	if (proc == c_p) {
+	    bp = NULL;
+	    ohp = NULL;
+	    hp = HAlloc(c_p, hsz);
+	}
+	else {
+	    hp = erts_alloc_message_heap(hsz,
+					 &bp,
+					 &ohp,
+					 proc,
+					 &proc_locks);
+	}
 
 #ifdef ERTS_HLT_DEBUG
 	hp_end = hp + hsz;
@@ -1864,7 +1874,7 @@ access_sched_local_btm(Process *c_p, Eterm pid,
 	}
 	else {
 	    Eterm tag = cancel ? am_cancel_timer : am_read_timer;
-	    if (is_value(tref))
+	    if (is_value(tref) && proc == c_p)
 		ref = tref;
 	    else {
 		write_ref_thing(hp,
@@ -1975,8 +1985,6 @@ try_access_sched_remote_btm(ErtsSchedulerData *esdp,
     }
     else {
 	Eterm tag, res, msg;
-	ErlOffHeap *ohp;
-	ErlHeapFragment* bp;
 	Uint hsz;
 	Eterm *hp;
 	ErtsProcLocks proc_locks = ERTS_PROC_LOCK_MAIN;
@@ -1985,11 +1993,7 @@ try_access_sched_remote_btm(ErtsSchedulerData *esdp,
 	if (time_left > (Sint64) MAX_SMALL)
 	    hsz += ERTS_SINT64_HEAP_SIZE(time_left);
 
-	hp = erts_alloc_message_heap(hsz,
-				     &bp,
-				     &ohp,
-				     c_p,
-				     &proc_locks);
+	hp = HAlloc(c_p, hsz);
 	if (cancel)
 	    tag = am_cancel_timer;
 	else
@@ -2004,7 +2008,7 @@ try_access_sched_remote_btm(ErtsSchedulerData *esdp,
 
 	msg = TUPLE3(hp, tag, tref, res);
 
-	erts_queue_message(c_p, &proc_locks, bp, msg, NIL);
+	erts_queue_message(c_p, &proc_locks, NULL, msg, NIL);
 
 	proc_locks &= ~ERTS_PROC_LOCK_MAIN;
 	if (proc_locks)
@@ -2149,7 +2153,7 @@ parse_bif_timer_options(Eterm option_list, int *async, int *info,
     if (async)
 	*async = 0;
     if (info)
-	*info = 0;
+	*info = 1;
     if (abs)
 	*abs = 0;
     if (accessor)
@@ -2218,13 +2222,19 @@ exit_cancel_bif_timer(ErtsHLTimer *tmr, void *vesdp)
     tmr->btm.proc_tree.parent = ERTS_HLT_PFIELD_NOT_IN_TABLE;
 
     if (sid == (Uint32) esdp->no) {
-	if (state == ERTS_TMR_STATE_ACTIVE)
+	if (state == ERTS_TMR_STATE_ACTIVE) {
+	    if (tmr->btm.bp)
+		free_message_buffer(tmr->btm.bp);
 	    hlt_delete_timer(esdp, tmr);
+	}
 	hl_timer_dec_refc(tmr, roflgs);
     }
     else {
-	if (state == ERTS_TMR_STATE_ACTIVE)
+	if (state == ERTS_TMR_STATE_ACTIVE) {
+	    if (tmr->btm.bp)
+		free_message_buffer(tmr->btm.bp);
 	    queue_canceled_timer(esdp, sid, (ErtsTimer *) tmr);
+	}
 	else
 	    hl_timer_dec_refc(tmr, roflgs);
     }
@@ -2398,7 +2408,7 @@ BIF_RETTYPE send_after_3(BIF_ALIST_3)
     tres = parse_timeout_pos(ERTS_PROC_GET_SCHDATA(BIF_P), BIF_ARG_1, NULL,
 			     0, &timeout_pos, &short_time);
     if (tres != 0)
-	BIF_ERROR(BIF_P, tres < 0 ? BADARG : SYSTEM_LIMIT);
+	BIF_ERROR(BIF_P, BADARG);
 
     return setup_bif_timer(BIF_P, timeout_pos, short_time,
 			   BIF_ARG_2, BIF_ARG_2, BIF_ARG_3, 0);
@@ -2416,7 +2426,7 @@ BIF_RETTYPE send_after_4(BIF_ALIST_4)
     tres = parse_timeout_pos(ERTS_PROC_GET_SCHDATA(BIF_P), BIF_ARG_1, NULL,
 			     abs, &timeout_pos, &short_time);
     if (tres != 0)
-	BIF_ERROR(BIF_P, tres < 0 ? BADARG : SYSTEM_LIMIT);
+	BIF_ERROR(BIF_P, BADARG);
 
     return setup_bif_timer(BIF_P, timeout_pos, short_time,
 			   BIF_ARG_2, accessor, BIF_ARG_3, 0);
@@ -2430,7 +2440,7 @@ BIF_RETTYPE start_timer_3(BIF_ALIST_3)
     tres = parse_timeout_pos(ERTS_PROC_GET_SCHDATA(BIF_P), BIF_ARG_1, NULL,
 			     0, &timeout_pos, &short_time);
     if (tres != 0)
-	BIF_ERROR(BIF_P, tres < 0 ? BADARG : SYSTEM_LIMIT);
+	BIF_ERROR(BIF_P, BADARG);
 
     return setup_bif_timer(BIF_P, timeout_pos, short_time,
 			   BIF_ARG_2, BIF_ARG_2, BIF_ARG_3, !0);
@@ -2448,7 +2458,7 @@ BIF_RETTYPE start_timer_4(BIF_ALIST_4)
     tres = parse_timeout_pos(ERTS_PROC_GET_SCHDATA(BIF_P), BIF_ARG_1, NULL,
 			     abs, &timeout_pos, &short_time);
     if (tres != 0)
-	BIF_ERROR(BIF_P, tres < 0 ? BADARG : SYSTEM_LIMIT);
+	BIF_ERROR(BIF_P, BADARG);
 
     return setup_bif_timer(BIF_P, timeout_pos, short_time,
 			   BIF_ARG_2, accessor, BIF_ARG_3, !0);
diff --git a/erts/emulator/beam/time.c b/erts/emulator/beam/time.c
index ea19d8b362..8bffdedb2b 100644
--- a/erts/emulator/beam/time.c
+++ b/erts/emulator/beam/time.c
@@ -135,39 +135,40 @@ struct ErtsTimerWheel_ {
     ErtsMonotonicTime next_timeout_time;
 };
 
-/* get the time (in units of TIW_ITIME) to the next timeout,
-   or -1 if there are no timeouts                     */
-
 static ERTS_INLINE ErtsMonotonicTime
-find_next_timeout(ErtsTimerWheel *tiw,
-		  ErtsMonotonicTime curr_time,
-		  ErtsMonotonicTime max_search_time)
+find_next_timeout(ErtsSchedulerData *esdp,
+		  ErtsTimerWheel *tiw,
+		  int search_all,
+		  ErtsMonotonicTime curr_time,       /* When !search_all */
+		  ErtsMonotonicTime max_search_time) /* When !search_all */
 {
     int start_ix, tiw_pos_ix;
     ErtsTWheelTimer *p;
-    int true_min_timeout;
+    int true_min_timeout = 0;
     ErtsMonotonicTime min_timeout, min_timeout_pos, slot_timeout_pos;
 
-    if (tiw->true_next_timeout_time)
-	return tiw->next_timeout_time;
-
     if (tiw->nto == 0) { /* no timeouts in wheel */
-	true_min_timeout = 0;
-	min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time + ERTS_MONOTONIC_DAY);
+	if (!search_all)
+	    min_timeout_pos = tiw->pos;
+	else {
+	    curr_time = erts_get_monotonic_time(esdp);
+	    tiw->pos = min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time);
+	}
+	min_timeout_pos += ERTS_MONOTONIC_TO_CLKTCKS(ERTS_MONOTONIC_DAY);
 	goto found_next;
     }
 
-    slot_timeout_pos = tiw->pos;
-    min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time + max_search_time);
+    slot_timeout_pos = min_timeout_pos = tiw->pos;
+    if (search_all)
+	min_timeout_pos += ERTS_MONOTONIC_TO_CLKTCKS(ERTS_MONOTONIC_DAY);
+    else
+	min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time + max_search_time);
 
     start_ix = tiw_pos_ix = (int) (tiw->pos & (ERTS_TIW_SIZE-1));
 
     do {
-	slot_timeout_pos++;
-	if (slot_timeout_pos >= min_timeout_pos) {
-	    true_min_timeout = 0;
+	if (++slot_timeout_pos >= min_timeout_pos)
 	    break;
-	}
 
 	p = tiw->w[tiw_pos_ix];
 
@@ -269,24 +270,16 @@ remove_timer(ErtsTimerWheel *tiw, ErtsTWheelTimer *p)
 
     p->slot = ERTS_TWHEEL_SLOT_INACTIVE;
 
-#if 0
-    p->next = NULL;
-    p->prev = NULL;
-#endif
-
     tiw->nto--;
 }
 
 ErtsMonotonicTime
 erts_check_next_timeout_time(ErtsSchedulerData *esdp)
 {
-    /*
-     * Called before a scheduler is about to wait. We wont
-     * check more than 10 minutes into the future.
-     */
-    return find_next_timeout(esdp->timer_wheel,
-			     erts_get_monotonic_time(esdp),
-			     ERTS_SEC_TO_MONOTONIC(10*60));
+    ErtsTimerWheel *tiw = esdp->timer_wheel;
+    if (tiw->true_next_timeout_time)
+	return tiw->next_timeout_time;
+    return find_next_timeout(esdp, tiw, 1, 0, 0);
 }
 
 #ifndef ERTS_TW_DEBUG
@@ -330,14 +323,11 @@ timeout_timer(ErtsTWheelTimer *p)
 {
     ErlTimeoutProc timeout;
     void *arg;
-#if 0
-    p->next = NULL;
-    p->prev = NULL;
-#endif
     p->slot = ERTS_TWHEEL_SLOT_INACTIVE;
     timeout = p->u.func.timeout;
     arg = p->u.func.arg;
     (*timeout)(arg);
+    ASSERT_NO_LOCKED_LOCKS;
 }
 
 void
@@ -508,7 +498,7 @@ erts_bump_timers(ErtsTimerWheel *tiw, ErtsMonotonicTime curr_time)
     tiw->next_timeout_time = curr_time + ERTS_MONOTONIC_DAY;
 
     /* Search at most two seconds ahead... */
-    (void) find_next_timeout(tiw, curr_time, ERTS_SEC_TO_MONOTONIC(2));
+    (void) find_next_timeout(NULL, tiw, 0, curr_time, ERTS_SEC_TO_MONOTONIC(2));
 }
 
 Uint