If the user configures NO_HZ_FULL and defines nohz_full=XXX on the
kerenl command line, or enables NO_HZ_FULL_ALL, but nohz fails
due to the machine having a unstable clock, warn about it.
We do not want users thinking that they are getting the benefit
of nohz when their machine can not support it.
Signed-off-by: Steven Rostedt <rost...@goodmis.org>
Index: linux-trace.git/kernel/time/tick-sched.c
===================================================================
--- linux-trace.git.orig/kernel/time/tick-sched.c
+++ linux-trace.git/kernel/time/tick-sched.c
@@ -178,6 +178,11 @@ static bool can_stop_full_tick(void)
*/
if (!sched_clock_stable) {
trace_tick_stop(0, "unstable sched clock\n");
+ /*
+ * Don't allow the user to think they can get
+ * full NO_HZ with this machine.
+ */
+ WARN_ONCE(1, "NO_HZ FULL will not work with unstable sched
clock");
return false;
}
#endif
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