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Groups > linux.kernel > #1370613

Re: [RFC] sched: unused cpu in affine workload

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFC] sched: unused cpu in affine workload
Date 2016-04-04 15:30 +0200
Message-ID <rkcJP-3AF-3@gated-at.bofh.it> (permalink)
References <rk83w-jm-13@gated-at.bofh.it> <rk8wx-tQ-1@gated-at.bofh.it> <rk8ZA-Wy-23@gated-at.bofh.it> <rk99g-118-21@gated-at.bofh.it>
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On Mon, Apr 04, 2016 at 11:38:44AM +0200, Ingo Molnar wrote:
> We'd upgrade that to O(nr_cpus^2), which is totally unrealistic with 16,000 CPUs 
> even in a slowpath - but it would probably cause problems even with 120 CPUs. It 
> will get quadratically worse as the number of CPUs in a system increases on its 
> current exponential trajectory ...

The arbitrary affinity thing is I think a packing problem, which is NP
hard IIRC.

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Thread

[RFC] sched: unused cpu in affine workload Jiri Olsa <jolsa@redhat.com> - 2016-04-04 10:30 +0200
  Re: [RFC] sched: unused cpu in affine workload Peter Zijlstra <peterz@infradead.org> - 2016-04-04 10:50 +0200
  Re: [RFC] sched: unused cpu in affine workload Ingo Molnar <mingo@kernel.org> - 2016-04-04 11:00 +0200
    Re: [RFC] sched: unused cpu in affine workload Ingo Molnar <mingo@kernel.org> - 2016-04-04 11:30 +0200
      Re: [RFC] sched: unused cpu in affine workload Ingo Molnar <mingo@kernel.org> - 2016-04-04 11:40 +0200
        Re: [RFC] sched: unused cpu in affine workload Peter Zijlstra <peterz@infradead.org> - 2016-04-04 15:30 +0200
          Re: [RFC] sched: unused cpu in affine workload Rik van Riel <riel@redhat.com> - 2016-04-04 21:50 +0200
            Re: [RFC] sched: unused cpu in affine workload Peter Zijlstra <peterz@infradead.org> - 2016-04-04 23:40 +0200
              Re: [RFC] sched: unused cpu in affine workload Jiri Olsa <jolsa@redhat.com> - 2016-04-05 11:00 +0200

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