On Tue, Jul 16, 2013 at 10:22:12AM -0400, Steven Rostedt wrote: > 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 <rost...@goodmis.org> > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 6960172..6f47049 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");
Seems good, indeed the warning and taint can be justified if the user filled the nohz_full mask. Ok I'll apply this and let the last word to Ingo in a pull request. Thanks. > return false; > } > #endif > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
