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-rw-r--r--erts/doc/src/erl.xml13
-rw-r--r--erts/emulator/beam/erl_init.c16
-rw-r--r--erts/emulator/beam/erl_process.c4
-rw-r--r--erts/emulator/beam/erl_process.h1
-rw-r--r--erts/etc/common/erlexec.c1
5 files changed, 35 insertions, 0 deletions
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 514ee5ffaf..50f90ec9df 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -738,6 +738,19 @@
<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">
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 0a57eb6d88..02efd2adb6 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -510,6 +510,8 @@ 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");
@@ -605,6 +607,7 @@ early_init(int *argc, char **argv) /*
int max_reader_groups;
int reader_groups;
+ erts_sched_compact_load = 1;
use_multi_run_queue = 1;
erts_printf_eterm_func = erts_printf_term;
erts_disable_tolerant_timeofday = 0;
@@ -1150,6 +1153,19 @@ 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);
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 2704359a8f..dba57e04ca 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -111,6 +111,7 @@ 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;
@@ -2215,6 +2216,9 @@ 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)
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index 296acc7367..c7d89d3bb3 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -88,6 +88,7 @@ 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;
diff --git a/erts/etc/common/erlexec.c b/erts/etc/common/erlexec.c
index 2bd576d8e8..95cb688b29 100644
--- a/erts/etc/common/erlexec.c
+++ b/erts/etc/common/erlexec.c
@@ -122,6 +122,7 @@ static char *plusM_other_switches[] = {
/* +s arguments with values */
static char *pluss_val_switches[] = {
"bt",
+ "cl",
"ct",
"wt",
"ss",