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Re: [PATCH] android: binder: Disable preemption while holding the global binder lock

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH] android: binder: Disable preemption while holding the global binder lock
Date 2016-09-14 18:20 +0200
Message-ID <shl4J-36P-5@gated-at.bofh.it> (permalink)
References (3 earlier) <sfTDz-2EA-3@gated-at.bofh.it> <sfUgh-36t-7@gated-at.bofh.it> <sgMTn-4wA-5@gated-at.bofh.it> <sgQtX-7bp-3@gated-at.bofh.it> <sh226-6k1-19@gated-at.bofh.it>
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On Tue, Sep 13, 2016 at 12:53:27PM -0700, Arve Hjønnevåg wrote:
> On Tue, Sep 13, 2016 at 12:32 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > cgroups should be irrelevant, PI is unaware of them.
> 
> I don't think cgroups are irrelevant. PI being unaware of them
> explains the problem I described. If the task that holds the lock is
> in a cgroup that has a low cpu.shares value, then boosting the task's
> priority within that group does necessarily make it any more likely to
> run.

Thing is, for FIFO/DL the important parameters (prio and deadline resp.)
are not cgroup dependent.

For CFS you're right, and as per usual, cgroups will be a royal pain.
While we can compute the total weight in the block chain, getting that
back to a task which is stuck in a cgroup is just not going to work
well.

The only 'solution' I can come up with in a hurry is, when the task is
boosted, move it to the root cgroup. That of course has a whole heap of
problems all on its own.

/me curses @ cgroups.. bloody stupid things.

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Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Christoph Hellwig <hch@infradead.org> - 2016-09-10 18:20 +0200
  Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Peter Zijlstra <peterz@infradead.org> - 2016-09-10 18:30 +0200
    Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Thomas Gleixner <tglx@linutronix.de> - 2016-09-10 18:50 +0200
      Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-09-10 19:30 +0200
        Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Todd Kjos <tkjos@android.com> - 2016-09-12 18:00 +0200
        Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Arve Hjønnevåg <arve@android.com> - 2016-09-13 05:50 +0200
          Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-09-13 08:50 +0200
            Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Arve Hjønnevåg <arve@android.com> - 2016-09-13 22:00 +0200
          Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Peter Zijlstra <peterz@infradead.org> - 2016-09-13 09:40 +0200
            Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Arve Hjønnevåg <arve@android.com> - 2016-09-13 22:00 +0200
              Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Peter Zijlstra <peterz@infradead.org> - 2016-09-14 09:20 +0200
                Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Peter Zijlstra <peterz@infradead.org> - 2016-09-14 09:50 +0200
                Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Peter Zijlstra <peterz@infradead.org> - 2016-09-14 15:40 +0200
              Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Peter Zijlstra <peterz@infradead.org> - 2016-09-14 18:20 +0200
                Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Peter Zijlstra <peterz@infradead.org> - 2016-09-14 18:20 +0200
                Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Peter Zijlstra <peterz@infradead.org> - 2016-09-14 19:00 +0200
                Re: [PATCH] android: binder: Disable preemption while holding the  global binder lock Todd Kjos <tkjos@android.com> - 2016-09-17 02:50 +0200

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