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authorRickard Green <[email protected]>2013-06-11 17:30:47 +0200
committerFredrik Gustafsson <[email protected]>2013-09-16 13:57:15 +0200
commit90351e1167a3bf21c2378306b68f560601e8415f (patch)
tree6824168cb5b70be26e3ebd929e679aa70cb3117c
parentc72b20183a780c7199d3959f09eb88c1a930a064 (diff)
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erts: Add the +sfwi system flag
+sfwi Interval Set scheduler forced wakeup interval. All run queues will be scanned each Interval milliseconds. While there are sleeping schedulers in the system, one scheduler will be woken for each non-empty run queue found. An Interval of zero disables this feature, which also is the default. This feature has been introduced as a temporary workaround for lengthy executing native code, and native code that do not bump reductions properly in OTP. When these bugs have be fixed the +sfwi flag will be removed. Conflicts: erts/doc/src/erl.xml erts/etc/common/erlexec.c
-rw-r--r--erts/doc/src/erl.xml14
-rw-r--r--erts/emulator/beam/erl_init.c16
-rw-r--r--erts/emulator/beam/erl_process.c85
-rw-r--r--erts/emulator/beam/erl_process.h4
-rw-r--r--erts/etc/common/erlexec.c3
5 files changed, 119 insertions, 3 deletions
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index f931445a3e..12cdb4b628 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -907,6 +907,20 @@
<p>For more information, see
<seealso marker="erlang#system_info_cpu_topology">erlang:system_info(cpu_topology)</seealso>.</p>
</item>
+ <tag><marker id="+sfwi"><c>+sfwi Interval</c></marker></tag>
+ <item>
+ <p>Set scheduler forced wakeup interval. All run queues will
+ be scanned each <c>Interval</c> milliseconds. While there are
+ sleeping schedulers in the system, one scheduler will be woken
+ for each non-empty run queue found. An <c>Interval</c> of zero
+ disables this feature, which also is the default.
+ </p>
+ <p>This feature has been introduced as a temporary workaround
+ for lengthy executing native code, and native code that do not
+ bump reductions properly in OTP. When these bugs have be fixed
+ the <c>+sfwi</c> flag will be removed.
+ </p>
+ </item>
<tag><marker id="+sws"><c>+sws default|legacy|proposal</c></marker></tag>
<item>
<p>Set scheduler wakeup strategy. Default is <c>legacy</c> (has been
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 1eb3dba240..7f52b111ac 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -1240,6 +1240,22 @@ erl_start(int argc, char **argv)
("suggested scheduler thread stack size %d kilo words\n",
erts_sched_thread_suggested_stack_size));
}
+ else if (has_prefix("fwi", sub_param)) {
+ long val;
+ arg = get_arg(sub_param+3, argv[i+1], &i);
+ errno = 0;
+ val = strtol(arg, NULL, 10);
+ if (errno != 0 || val < 0) {
+ erts_fprintf(stderr,
+ "bad scheduler forced wakeup "
+ "interval %s\n",
+ arg);
+ erts_usage();
+ }
+#ifdef ERTS_SMP
+ erts_runq_supervision_interval = val;
+#endif
+ }
else {
erts_fprintf(stderr, "bad scheduling option %s\n", argv[i]);
erts_usage();
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 9425fa7088..b84b5b39a5 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -218,6 +218,10 @@ static erts_smp_atomic32_t function_calls;
#ifdef ERTS_SMP
static erts_smp_atomic32_t doing_sys_schedule;
static erts_smp_atomic32_t no_empty_run_queues;
+long erts_runq_supervision_interval = 0;
+static ethr_event runq_supervision_event;
+static erts_tid_t runq_supervisor_tid;
+static erts_atomic_t runq_supervisor_sleeping;
#else /* !ERTS_SMP */
ErtsSchedulerData *erts_scheduler_data;
#endif
@@ -1885,7 +1889,13 @@ empty_runq(ErtsRunQueue *rq)
*/
ASSERT(0 <= empty && empty < 2*erts_no_run_queues);
#endif
- erts_smp_atomic32_inc_relb(&no_empty_run_queues);
+ if (!erts_runq_supervision_interval)
+ erts_smp_atomic32_inc_relb(&no_empty_run_queues);
+ else {
+ erts_smp_atomic32_inc_mb(&no_empty_run_queues);
+ if (erts_atomic_read_nob(&runq_supervisor_sleeping))
+ ethr_event_set(&runq_supervision_event);
+ }
}
}
@@ -1903,7 +1913,14 @@ non_empty_runq(ErtsRunQueue *rq)
*/
ASSERT(0 < empty && empty <= 2*erts_no_run_queues);
#endif
- erts_smp_atomic32_dec_relb(&no_empty_run_queues);
+ if (!erts_runq_supervision_interval)
+ erts_smp_atomic32_dec_relb(&no_empty_run_queues);
+ else {
+ erts_aint32_t no;
+ no = erts_smp_atomic32_dec_read_mb(&no_empty_run_queues);
+ if (no > 0 && erts_atomic_read_nob(&runq_supervisor_sleeping))
+ ethr_event_set(&runq_supervision_event);
+ }
}
}
@@ -2505,7 +2522,6 @@ try_inc_no_active_runqs(int active)
return 0;
}
-
static ERTS_INLINE int
chk_wake_sched(ErtsRunQueue *crq, int ix, int activate)
{
@@ -3829,6 +3845,53 @@ set_wakeup_other_data(void)
}
}
+static int
+no_runqs_to_supervise(void)
+{
+ int used;
+ erts_aint32_t nerq = erts_smp_atomic32_read_acqb(&no_empty_run_queues);
+ if (nerq <= 0)
+ return 0;
+ get_no_runqs(NULL, &used);
+ if (nerq >= used)
+ return 0;
+ return used;
+}
+
+static void *
+runq_supervisor(void *unused)
+{
+ while (1) {
+ int ix, no_rqs;
+
+ erts_milli_sleep(erts_runq_supervision_interval);
+ no_rqs = no_runqs_to_supervise();
+ if (!no_rqs) {
+ erts_atomic_set_nob(&runq_supervisor_sleeping, 1);
+ while (1) {
+ ethr_event_reset(&runq_supervision_event);
+ no_rqs = no_runqs_to_supervise();
+ if (no_rqs) {
+ erts_atomic_set_nob(&runq_supervisor_sleeping, 0);
+ break;
+ }
+ ethr_event_wait(&runq_supervision_event);
+ }
+ }
+
+ for (ix = 0; ix < no_rqs; ix++) {
+ ErtsRunQueue *rq = ERTS_RUNQ_IX(ix);
+ if (ERTS_RUNQ_FLGS_GET(rq) & ERTS_RUNQ_FLG_NONEMPTY) {
+ erts_smp_runq_lock(rq);
+ if (rq->len != 0)
+ wake_scheduler_on_empty_runq(rq); /* forced wakeup... */
+ erts_smp_runq_unlock(rq);
+ }
+ }
+ }
+ return NULL;
+}
+
#endif
void
@@ -5235,6 +5298,22 @@ erts_start_schedulers(void)
ethr_thr_opts opts = ETHR_THR_OPTS_DEFAULT_INITER;
opts.detached = 1;
+
+#ifdef ERTS_SMP
+ if (erts_runq_supervision_interval) {
+ opts.suggested_stack_size = 16;
+ erts_atomic_init_nob(&runq_supervisor_sleeping, 0);
+ if (0 != ethr_event_init(&runq_supervision_event))
+ erl_exit(1, "Failed to create run-queue supervision event\n");
+ if (0 != ethr_thr_create(&runq_supervisor_tid,
+ runq_supervisor,
+ NULL,
+ &opts))
+ erl_exit(1, "Failed to create run-queue supervision thread\n");
+
+ }
+#endif
+
opts.suggested_stack_size = erts_sched_thread_suggested_stack_size;
if (wanted < 1)
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index 968971ed4c..9b0e9f1ccd 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -371,6 +371,10 @@ struct ErtsRunQueue_ {
} ports;
};
+#ifdef ERTS_SMP
+extern long erts_runq_supervision_interval;
+#endif
+
typedef union {
ErtsRunQueue runq;
char align[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(ErtsRunQueue))];
diff --git a/erts/etc/common/erlexec.c b/erts/etc/common/erlexec.c
index 52add1c1ba..c4bdc4ee4b 100644
--- a/erts/etc/common/erlexec.c
+++ b/erts/etc/common/erlexec.c
@@ -124,6 +124,9 @@ static char *pluss_val_switches[] = {
"bwt",
"cl",
"ct",
+ "fwi",
+ "tbt",
+ "wct",
"wt",
"ws",
"ss",