Messages in this thread | | | Subject | Re: [tip:timers/urgent] NOHZ: Properly feed cpufreq ondemand governor | From | Eero Nurkkala <> | Date | Wed, 27 May 2009 15:18:32 +0300 |
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On Wed, 2009-05-27 at 13:57 +0200, Nurkkala Eero.An (EXT-Offcode/Oulu) wrote: > Commit-ID: 4e67ac87c460a3c876019fa05149591122ec5287 > Gitweb: http://git.kernel.org/tip/4e67ac87c460a3c876019fa05149591122ec5287 > Author: Eero Nurkkala <ext-eero.nurkkala@nokia.com> > AuthorDate: Mon, 25 May 2009 09:57:37 +0300 > Committer: Thomas Gleixner <tglx@linutronix.de> > CommitDate: Wed, 27 May 2009 13:55:00 +0200 > > NOHZ: Properly feed cpufreq ondemand governor > > A call from irq_exit() may occasionally pause the timing > info for cpufreq ondemand governor. This results in the > cpufreq ondemand governor to fail to calculate the > system load properly. Thus, relocate the checks for this > particular case to keep the governor always functional. > > [ tglx: moved the check to the top of the function ] > > Signed-off-by: Eero Nurkkala <ext-eero.nurkkala@nokia.com> > Reported-by: Tero Kristo <tero.kristo@nokia.com> > Acked-by: Rik van Riel <riel@redhat.com> > Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> > LKML-Reference: <12432346571351-git-send-email-ext-eero.nurkkala@nokia.com> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > > > --- > kernel/time/tick-sched.c | 12 ++++++++---- > 1 files changed, 8 insertions(+), 4 deletions(-) > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index d3f1ef4..d3d6f3f 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -218,8 +218,15 @@ void tick_nohz_stop_sched_tick(int inidle) > struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev; > int cpu; > > - local_irq_save(flags); > + /* > + * Call to tick_nohz_start_idle stops the last_update_time from being > + * updated. Thus, it must not be called in the event we are called from > + * irq_exit() with the prior state different than idle. > + */ > + if (!inidle && !ts->inidle) > + return; > > + local_irq_save(flags); > cpu = smp_processor_id(); > ts = &per_cpu(tick_cpu_sched, cpu); > now = tick_nohz_start_idle(ts); > @@ -239,9 +246,6 @@ void tick_nohz_stop_sched_tick(int inidle) > if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) > goto end; > > - if (!inidle && !ts->inidle) > - goto end; > - > ts->inidle = 1; > > if (need_resched())
A quick note: Now ts is uninitialized? So ts->inidle could cause troubles, no?
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