On 18 February 2013 11:51, Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> wrote: > On 02/18/2013 04:04 PM, Srivatsa S. Bhat wrote: >> On 02/18/2013 03:54 PM, Vincent Guittot wrote: >>> On 15 February 2013 20:40, Srivatsa S. Bhat >>> <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> wrote: >>>> Hi Vincent, >>>> >>>> On 02/15/2013 06:58 PM, Vincent Guittot wrote: >>>>> Hi Srivatsa, >>>>> >>>>> I have run some tests with you branch (thanks Paul for the git tree) >>>>> and you will find results below. >>>>> >>>> >>>> Thank you very much for testing this patchset! >>>> >>>>> The tests condition are: >>>>> - 5 CPUs system in 2 clusters >>>>> - The test plugs/unplugs CPU2 and it increases the system load each 20 >>>>> plug/unplug sequence with either more cyclictests threads >>>>> - The test is done with all CPUs online and with only CPU0 and CPU2 >>>>> >>>>> The main conclusion is that there is no differences with and without >>>>> your patches with my stress tests. I'm not sure that it was the >>>>> expected results but the cpu_down is already quite low : 4-5ms in >>>>> average >>>>> >>>> >>>> Atleast my patchset doesn't perform _worse_ than mainline, with respect >>>> to cpu_down duration :-) >>> >>> yes exactly and it has pass more than 400 consecutive plug/unplug on >>> an ARM platform >>> >> >> Great! However, did you turn on CPU_IDLE during your tests? >> >> In my tests, I had turned off cpu idle in the .config, like I had mentioned in >> the cover letter. I'm struggling to get it working with CPU_IDLE/INTEL_IDLE >> turned on, because it gets into a lockup almost immediately. It appears that >> the lock-holder of clockevents_lock never releases it, for some reason.. >> See below for the full log. Lockdep has not been useful in debugging this, >> unfortunately :-( >> > > Ah, nevermind, the following diff fixes it :-) I had applied this fix on v5 > and tested but it still had races where I used to hit the lockups. Now after > I fixed all the memory barrier issues that Paul and Oleg pointed out in v5, > I applied this fix again and tested it just now - it works beautifully! :-) My tests have been done without cpuidle because i have some issues with function tracer and cpuidle But the cpu hotplug and cpuidle work well when I run the tests without enabling the function tracer Vincent > > I'll include this fix and post a v6 soon. > > Regards, > Srivatsa S. Bhat > > ---------------------------------------------------------------------------> > > > diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c > index 30b6de0..ca340fd 100644 > --- a/kernel/time/clockevents.c > +++ b/kernel/time/clockevents.c > @@ -17,6 +17,7 @@ > #include <linux/module.h> > #include <linux/notifier.h> > #include <linux/smp.h> > +#include <linux/cpu.h> > > #include "tick-internal.h" > > @@ -431,6 +432,7 @@ void clockevents_notify(unsigned long reason, void *arg) > unsigned long flags; > int cpu; > > + get_online_cpus_atomic(); > raw_spin_lock_irqsave(&clockevents_lock, flags); > clockevents_do_notify(reason, arg); > > @@ -459,6 +461,7 @@ void clockevents_notify(unsigned long reason, void *arg) > break; > } > raw_spin_unlock_irqrestore(&clockevents_lock, flags); > + put_online_cpus_atomic(); > } > EXPORT_SYMBOL_GPL(clockevents_notify); > #endif > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
