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Re: [patch] workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs

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On Wed, 2015-07-22 at 16:55 +0200, Mike Galbraith wrote:
> On Wed, 2015-07-22 at 10:11 -0400, Tejun Heo wrote:
> > On Wed, Jul 22, 2015 at 07:24:46AM +0200, Mike Galbraith wrote:
> > > WORK_CPU_UNBOUND work items queued to a bound workqueue always run
> > > locally.  This is a good thing normally, but not when the user has
> > 
> > The constant name used there is a bit misleading but you can't put
> > work items which are queued w/ queue_work() on foreign cpus by
> > default.  queue_work() has always guaranteed local execution.  The
> > problem is that workqueue can't currently tell whether a queue_work()
> > user expects cpu locality for correctness or optimization.  It'd be
> > great if we introduce queue_work_on_local() or sth and replace
> > correctness ones with it but that involves auditing each and every
> > queue_work() usage.  If anybody is up for the task, I'd be happy to
> > help.
> 
> Oh well.  That puts a big dent in the utility of wq_unbound_cpumask, but
> too bad.  If someone has a big enough HPC itch, they'll scratch it.

Ew, looking at the numbers, they may prefer to either a) pretend to not
notice, or b) scurry off to HPC'R'US store if a) won't fly ;-)

	-Mike

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[RFC] workqueue: avoiding unbounded wq on isolated CPUs by default Daniel Bristot de Oliveira <bristot@redhat.com> - 2015-07-16 21:20 +0200
  Re: [RFC] workqueue: avoiding unbounded wq on isolated CPUs by  default Tejun Heo <tj@kernel.org> - 2015-07-16 21:30 +0200
    Re: [RFC] workqueue: avoiding unbounded wq on isolated CPUs by  default Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-07-17 06:30 +0200
      Re: [RFC] workqueue: avoiding unbounded wq on isolated CPUs by  default Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-07-19 10:10 +0200
        Re: [RFC] workqueue: avoiding unbounded wq on isolated CPUs by  default Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-07-19 14:20 +0200
        [patch] workqueue: schedule WORK_CPU_UNBOUND work on  wq_unbound_cpumask CPUs Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-07-22 07:30 +0200
          [PATCH] workqueue: avoiding unbounded wq on isolated CPUs by default Daniel Bristot de Oliveira <bristot@redhat.com> - 2015-07-22 14:50 +0200
          Re: [patch] workqueue: schedule WORK_CPU_UNBOUND work on  wq_unbound_cpumask CPUs Tejun Heo <tj@kernel.org> - 2015-07-22 16:20 +0200
            Re: [patch] workqueue: schedule WORK_CPU_UNBOUND work on  wq_unbound_cpumask CPUs Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-07-22 17:00 +0200
              Re: [patch] workqueue: schedule WORK_CPU_UNBOUND work on  wq_unbound_cpumask CPUs Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-07-22 17:20 +0200
                Re: [patch] workqueue: schedule WORK_CPU_UNBOUND work on  wq_unbound_cpumask CPUs Tejun Heo <tj@kernel.org> - 2015-07-22 17:30 +0200

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