Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 2/2] nohz: Warn if the machine can not perform nohz_full | Date | Tue, 14 May 2013 18:02:52 +0200 |
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From: Steven Rostedt <rostedt@goodmis.org>
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@goodmis.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> --- kernel/time/tick-sched.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index bc67d42..cfc798b 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 -- 1.7.5.4
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