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! :-) 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
