Messages in this thread |  | | | Date | Fri, 27 May 2011 20:53:02 +0530 | | From | Santosh Shilimkar <> | | Subject | Re: [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM |
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Peter,
On 5/26/2011 10:53 PM, Peter Zijlstra wrote: > On Thu, 2011-05-26 at 19:17 +0200, Peter Zijlstra wrote: >> On Thu, 2011-05-26 at 19:04 +0200, Oleg Nesterov wrote: >>> On 05/26, Peter Zijlstra wrote: >>>> >>>> @@ -2636,7 +2636,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) >>>> * to spin on ->on_cpu if p is current, since that would >>>> * deadlock. >>>> */ >>>> - if (p == current) { >>>> + if (cpu == smp_processor_id()) { >>>> + p->sched_contributes_to_load = 0; >>>> ttwu_queue(p, cpu); >>> >>> Btw. I do not pretend I really understand se->vruntime, but in this >>> case we are doing enqueue_task() without ->task_waking(), however we >>> pass ENQUEUE_WAKING. Is it correct? >> >> No its not, that's the thing that I got wrong the first time and caused >> these pauses. > > We'd end up with something like the below, which isn't too different > from what I've now got queued. > > It has the extra cpu == smp_processor_id() check, but I'm not sure this > whole case is worth the trouble. I could go stick some counters in to > verify how often all this happens I guess. > Are you planning send version of this patch for stable .39 too ?
Regards Santosh
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