Commit-ID: e12d0271774fea9fddf1e2a7952a0bffb2ee8e8b Gitweb: http://git.kernel.org/tip/e12d0271774fea9fddf1e2a7952a0bffb2ee8e8b Author: Steven Rostedt <rostedt@xxxxxxxxxxx> AuthorDate: Fri, 10 May 2013 17:12:28 -0400 Committer: Frederic Weisbecker <fweisbec@xxxxxxxxx> CommitDate: Thu, 20 Jun 2013 01:15:51 +0200 nohz: Warn if the machine can not perform nohz_full If the user configures NO_HZ_FULL and defines nohz_full=XXX on the kernel 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 <rostedt@xxxxxxxxxxx> Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Li Zhong <zhong@xxxxxxxxxxxxxxxxxx> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> --- kernel/time/tick-sched.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index f420813..d87d22c 100644 --- a/kernel/time/tick-sched.c +++ b/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 -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html