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Merge branch 'rickard/sched-compact-load/OTP-9695'

* rickard/sched-compact-load/OTP-9695:
  Add switch that can disable scheduler compaction of load
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commit ac59f1fae260d24ea23f577b739101ad64ffa4fa 2 parents 1d4c9de + ac7dcc2
@rickard-green rickard-green authored
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13 erts/doc/src/erl.xml
@@ -745,6 +745,19 @@
<seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, SchedulerBindType)</seealso>.
</p>
</item>
+ <tag><marker id="+scl"><c>+scl true|false</c></marker></tag>
+ <item>
+ <p>Enable or disable scheduler compaction of load. By default
+ scheduler compaction of load is enabled. When enabled, load
+ balancing will strive for a load distribution which causes
+ as many scheduler threads as possible to be fully loaded (i.e.,
+ not run out of work). This is accomplished by migrating load
+ (e.g. runnable processes) into a smaller set of schedulers
+ when schedulers frequently run out of work. When disabled,
+ the frequency with which schedulers run out of work will
+ not be taken into account by the load balancing logic.
+ </p>
+ </item>
<tag><marker id="+sct"><c>+sct CpuTopology</c></marker></tag>
<item>
<list type="bulleted">
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16 erts/emulator/beam/erl_init.c
@@ -513,6 +513,8 @@ void erts_usage(void)
erts_fprintf(stderr, "-rg amount set reader groups limit\n");
erts_fprintf(stderr, "-sbt type set scheduler bind type, valid types are:\n");
erts_fprintf(stderr, " u|ns|ts|ps|s|nnts|nnps|tnnps|db\n");
+ erts_fprintf(stderr, "-scl bool enable/disable compaction of scheduler load,\n");
+ erts_fprintf(stderr, " see the erl(1) documentation for more info.\n");
erts_fprintf(stderr, "-sct cput set cpu topology,\n");
erts_fprintf(stderr, " see the erl(1) documentation for more info.\n");
erts_fprintf(stderr, "-swt val set scheduler wakeup threshold, valid values are:\n");
@@ -610,6 +612,7 @@ early_init(int *argc, char **argv) /*
char envbuf[21]; /* enough for any 64-bit integer */
size_t envbufsz;
+ erts_sched_compact_load = 1;
use_multi_run_queue = 1;
erts_printf_eterm_func = erts_printf_term;
erts_disable_tolerant_timeofday = 0;
@@ -1198,6 +1201,19 @@ erl_start(int argc, char **argv)
erts_usage();
}
}
+ else if (has_prefix("cl", sub_param)) {
+ arg = get_arg(sub_param+2, argv[i+1], &i);
+ if (sys_strcmp("true", arg) == 0)
+ erts_sched_compact_load = 1;
+ else if (sys_strcmp("false", arg) == 0)
+ erts_sched_compact_load = 0;
+ else {
+ erts_fprintf(stderr,
+ "bad scheduler compact load value '%s'\n",
+ arg);
+ erts_usage();
+ }
+ }
else if (has_prefix("ct", sub_param)) {
arg = get_arg(sub_param+2, argv[i+1], &i);
res = erts_init_cpu_topology_string(arg);
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4 erts/emulator/beam/erl_process.c
@@ -114,6 +114,7 @@ static Sint p_serial;
static Uint p_serial_mask;
static Uint p_serial_shift;
+int erts_sched_compact_load;
Uint erts_no_schedulers;
Uint erts_max_processes = ERTS_DEFAULT_MAX_PROCESSES;
Uint erts_process_tab_index_mask;
@@ -2949,6 +2950,9 @@ check_balance(ErtsRunQueue *c_rq)
mmax_len = run_queue_info[qix].max_len;
}
+ if (!erts_sched_compact_load)
+ goto all_active;
+
if (!forced && half_full_scheds != blnc_no_rqs) {
int min = 1;
if (min < half_full_scheds)
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1  erts/emulator/beam/erl_process.h
@@ -95,6 +95,7 @@ struct saved_calls {
};
extern Export exp_send, exp_receive, exp_timeout;
+extern int erts_sched_compact_load;
extern Uint erts_no_schedulers;
extern Uint erts_no_run_queues;
extern int erts_sched_thread_suggested_stack_size;
View
1  erts/etc/common/erlexec.c
@@ -121,6 +121,7 @@ static char *plusM_other_switches[] = {
/* +s arguments with values */
static char *pluss_val_switches[] = {
"bt",
+ "cl",
"ct",
"wt",
"ss",
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