Messages in this thread | | | Date | Fri, 15 Jun 2012 10:53:31 +0900 | From | Tejun Heo <> | Subject | Re: [RFC patch 2/5] smpboot: Provide infrastructure for percpu hotplug threads |
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On Thu, Jun 14, 2012 at 10:17:28AM +0200, Peter Zijlstra wrote: > On Thu, 2012-06-14 at 10:08 +0200, Peter Zijlstra wrote: > > On Wed, 2012-06-13 at 20:56 +0200, Thomas Gleixner wrote: > > > If it's just a spurious wakeup then it goes back to sleep right away > > > as nothing cleared the park bit. > > > > Your spurious wakeup will have destroyed the binding though. So you need > > to be careful. > > We should probably do something like the below.. > > TJ does this wreck workqueues? Its somewhat 'creative' in that regard > and really wants fixing. > > --- > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -5018,6 +5018,8 @@ void do_set_cpus_allowed(struct task_str > > cpumask_copy(&p->cpus_allowed, new_mask); > p->nr_cpus_allowed = cpumask_weight(new_mask); > + if (p->nr_cpus_allowed != 1) > + p->flags &= ~PF_THREAD_BOUND;
The only reason wq workers use PF_THREAD_BOUND is to prevent userland from mucking with cpus_allowed, so the above wouldn't break anything in itself although userland would be able to wreck it afterwards.
Thanks.
-- tejun
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