Merge branch 'rickard/sched-busy-wait/OTP-10044' into maint-r15

* rickard/sched-busy-wait/OTP-10044:
  Add switch controlling scheduler busy wait

Conflicts:
	erts/emulator/beam/erl_process.c
	erts/emulator/beam/erl_process.h

1 files changed, 12 insertions, 0 deletions

diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index faf980b237..8bcba9de15 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -511,6 +511,8 @@ 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, "-sbwt val   set scheduler busy wait threshold, valid values are:\n");
+    erts_fprintf(stderr, "            none|very_short|short|medium|long|very_long.\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");
@@ -1200,6 +1202,16 @@ erl_start(int argc, char **argv)
 		    erts_usage();
 		}
 	    }
+	    else if (has_prefix("bwt", sub_param)) {
+		arg = get_arg(sub_param+3, argv[i+1], &i);
+		if (erts_sched_set_busy_wait_threshold(arg) != 0) {
+		    erts_fprintf(stderr, "bad scheduler busy wait threshold: %s\n",
+				 arg);
+		    erts_usage();
+		}
+		VERBOSE(DEBUG_SYSTEM,
+			("scheduler wakup threshold: %s\n", arg));
+	    }
 	    else if (has_prefix("cl", sub_param)) {
 		arg = get_arg(sub_param+2, argv[i+1], &i);
 		if (sys_strcmp("true", arg) == 0)