Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on housekeeping

From	Frederic Weisbecker <fweisbec@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on housekeeping
Date	2017-09-01 01:10 +0200
Message-ID	<ukGKZ-3MS-5@gated-at.bofh.it> (permalink)
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On Thu, Aug 31, 2017 at 08:53:56PM +0200, Thomas Gleixner wrote:
> On Mon, 28 Aug 2017, Frederic Weisbecker wrote:
> > On Mon, Aug 28, 2017 at 06:24:16PM +0200, Peter Zijlstra wrote:
> > > On Mon, Aug 28, 2017 at 05:27:15PM +0200, Frederic Weisbecker wrote:
> > > > Although for example I guess (IIUC) that if you create an unbound
> > > > timer on a NULL domain, it will be stuck on it for ever as we can't
> > > > walk any hierarchy from the current CPU domain.
> > > 
> > > Not sure what you're on about. Timers have their own hierarchy.
> > 
> > Check out get_nohz_timer_target() which relies on scheduler hierarchies to
> > look up a CPU to enqueue an unpinned timer on.
> 
> Which is one of the most idiotic things we have in that code
> path. Anna-Maria has posted this series which gets rid of that nonsense, by
> queueing the timer on the current cpu into a wheel, which gets pulled in by
> others. That makes a lot of sense because most of these timers get canceled
> before expiry anyway. But we still need to fix the fallout and the few
> corner cases to make that work reliably. We'll do that hopefully sooner
> than later.

Sure, I definetly agree with that change.

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Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on  housekeeping Peter Zijlstra <peterz@infradead.org> - 2017-08-28 12:20 +0200
  Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on  housekeeping Frederic Weisbecker <fweisbec@gmail.com> - 2017-08-28 15:30 +0200
    Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on  housekeeping Peter Zijlstra <peterz@infradead.org> - 2017-08-28 15:40 +0200
      Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on  housekeeping Frederic Weisbecker <fweisbec@gmail.com> - 2017-08-28 17:30 +0200
        Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on  housekeeping Peter Zijlstra <peterz@infradead.org> - 2017-08-28 18:30 +0200
          Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on  housekeeping Christopher Lameter <cl@linux.com> - 2017-08-28 19:00 +0200
          Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on  housekeeping Frederic Weisbecker <fweisbec@gmail.com> - 2017-08-28 19:40 +0200
            Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on  housekeeping Thomas Gleixner <tglx@linutronix.de> - 2017-08-31 21:00 +0200
              Re: [RFC PATCH 12/12] housekeeping: Reimplement isolcpus on  housekeeping Frederic Weisbecker <fweisbec@gmail.com> - 2017-09-01 01:10 +0200

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