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authorSteven Rostedt <rostedt@goodmis.org>2013-07-16 10:22:12 -0400
committerFrederic Weisbecker <fweisbec@gmail.com>2013-07-24 20:30:33 +0200
commit543487c7a2670bb0d96c00673a44b74360e3b6c1 (patch)
tree91aee197ada7a72a73ee34eaa339914be5468039 /kernel/time
parent3b2f64d00c46e1e4e9bd0bb9bb12619adac27a4b (diff)
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nohz: Do not warn about unstable tsc unless user uses nohz_full
If the user enables CONFIG_NO_HZ_FULL and runs the kernel on a machine with an unstable TSC, it will produce a WARN_ON dump as well as taint the kernel. This is a bit extreme for a kernel that just enables a feature but doesn't use it. The warning should only happen if the user tries to use the feature by either adding nohz_full to the kernel command line, or by enabling CONFIG_NO_HZ_FULL_ALL that makes nohz used on all CPUs at boot up. Note, this second feature should not (yet) be used by distros or anyone that doesn't care if NO_HZ is used or not. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Kevin Hilman <khilman@linaro.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/tick-sched.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index e80183f..1102534 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -182,7 +182,8 @@ static bool can_stop_full_tick(void)
* 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");
+ WARN_ONCE(have_nohz_full_mask,
+ "NO_HZ FULL will not work with unstable sched clock");
return false;
}
#endif