On 2014/04/24 17:41, Viresh Kumar wrote: > On 24 April 2014 14:01, Daniel Sangorrin <daniel.sangorrin@xxxxxxxxxxxxx> wrote: >> In kernel/cpuset.c:quiesce_cpuset() you are using the function >> 'smp_call_function_any' which asks CPU cores in 'cpumask' to >> execute the functions 'hrtimer_quiesce_cpu' and 'timer_quiesce_cpu'. >> >> In the case above, 'cpumask' corresponds to core 0. Since I'm forcing >> the call to be executed from core 1 (by using taskset), >> an inter-processor interrupt is sent to core 0 for those functions >> to be executed. > > Ahh, I understood that now :) .. So we are setting cpuset.quiesce from CPU1 > which will do a IPI to get migrate_timers called on CPU0.. I was setting quiesce > from CPU0 only in my tests :) > > But how does this work fine on x86 then? There we should have exactly same > problem, isn't it? Yeah, I'm not sure why it is working on 3.15 x86_64 but not in 3.10 x86_64. Perhaps it's related to this patch: https://lkml.org/lkml/2013/9/19/349 >> Ok, thank you! I see that you have already fixed the problem. I tested >> your tree on ARM and now it seems to work correctly. > > Yeah, I just pushed your changes as well at the time I wrote last mail :) Oh, I see! Why didn't you just apply the patch on top of your tree so that the information included in the git commit (e.g: my name and mail) remains? This part: cpuset: quiesce: change irq disable/enable by irq save/restore The function __migrate_timers can be called under interrupt context or thread context depending on the core where the system call was executed. In case it executes under interrupt context, it seems a bad idea to leave interrupts enabled after migrating the timers. In fact, this caused kernel errors on the ARM architecture and on the x86_64 architecture with the 3.10 kernel (backported version of the cpuset-quiesce patch). Signed-off-by: Daniel Sangorrin <daniel.sangorrin@xxxxxxxxxxxxx> Signed-off-by: Yoshitake Kobayashi <yoshitake.kobayashi@xxxxxxxxxxxxx> Thanks, Daniel -- Toshiba Corporate Software Engineering Center Daniel SANGORRIN E-mail: daniel.sangorrin@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
