Re: [PATCH 3/3] sched: Implement interface for cgroup unified hierarchy

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From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 3/3] sched: Implement interface for cgroup unified hierarchy
Date	Thu, 17 Sep 2015 16:50:02 +0200
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On Sat, Sep 12, 2015 at 10:40:07AM -0400, Tejun Heo wrote:
> So, one of the problems is that the kernel can't have tasks w/o
> runnable CPUs, so we have to some workaround when, for whatever
> reason, a task ends up with no CPU that it can run on.

No, just refuse that configuration.

> You say cpuset isn't a layering thing but that simply isn't true.
> It's a cgroup-scope CPU mask.  It layers atop task affinities
> restricting what they can be configured to, limiting the effective
> cpumask to the intersection of actually existing CPUs and overriding
> individual affinity setting when the intersection doesn't exist.

No, just fail.

> The kernel does not update all CPU affinity masks when a CPU goes down
> or comes up.

I'd be happy to fail a CPU down for user tasks where this is the last
runnable CPU of.
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Thread

Re: [PATCH 3/3] sched: Implement interface for cgroup unified hierarchy Paul Turner <pjt@google.com> - 2015-09-09 15:00 +0200
  Re: [PATCH 3/3] sched: Implement interface for cgroup unified  hierarchy Tejun Heo <tj@kernel.org> - 2015-09-12 16:50 +0200
    Re: [PATCH 3/3] sched: Implement interface for cgroup unified  hierarchy Peter Zijlstra <peterz@infradead.org> - 2015-09-17 16:50 +0200
      Re: [PATCH 3/3] sched: Implement interface for cgroup unified  hierarchy Tejun Heo <tj@kernel.org> - 2015-09-17 17:00 +0200
        Re: [PATCH 3/3] sched: Implement interface for cgroup unified  hierarchy Peter Zijlstra <peterz@infradead.org> - 2015-09-17 17:50 +0200
      Re: [PATCH 3/3] sched: Implement interface for cgroup unified  hierarchy Peter Zijlstra <peterz@infradead.org> - 2015-09-17 17:20 +0200
        Re: [PATCH 3/3] sched: Implement interface for cgroup unified  hierarchy Peter Zijlstra <peterz@infradead.org> - 2015-09-17 18:00 +0200
        Re: [PATCH 3/3] sched: Implement interface for cgroup unified  hierarchy Tejun Heo <tj@kernel.org> - 2015-09-17 18:00 +0200
    Re: [PATCH 3/3] sched: Implement interface for cgroup unified  hierarchy Tejun Heo <tj@kernel.org> - 2015-09-18 01:30 +0200
    Re: [PATCH 3/3] sched: Implement interface for cgroup unified hierarchy Paul Turner <pjt@google.com> - 2015-09-18 13:30 +0200

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