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Re: TREE_SRCU slows hotplug by factor ~16

From Mike Galbraith <efault@gmx.de>
Newsgroups linux.kernel
Subject Re: TREE_SRCU slows hotplug by factor ~16
Date 2017-04-24 07:30 +0200
Message-ID <tzEJr-2O1-1@gated-at.bofh.it> (permalink)
References <tzCoh-M8-1@gated-at.bofh.it> <tzD10-1ml-3@gated-at.bofh.it>
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On Sun, 2017-04-23 at 20:32 -0700, Paul E. McKenney wrote:
> On Mon, Apr 24, 2017 at 04:48:09AM +0200, Mike Galbraith wrote:
> > Greetings,
> > 
> > Running Steven's hotplug stress script in tip w. CLASSIC_SRCU takes 55s
> > in my i4790 box, whereas TREE_SRCU takes over 16m.  (Master with the
> > same config does it in 39s.. but then lockdep isn't enabled in master)
> 
> That doesn't sound good...
> 
> But exactly which version are you using?  There were some 8x slowdowns
> earlier this week that have since been fixed.  Also, how many CPUs are
> on your system?

4 cores+SMT, tip.yesterday_afternoon (precise!) was initial test point,
tip.this_morning (v4.11-rc7-955-g76f8909e1cd8) is still slow.

	-Mike

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Thread

TREE_SRCU slows hotplug by factor ~16 Mike Galbraith <efault@gmx.de> - 2017-04-24 05:00 +0200
  Re: TREE_SRCU slows hotplug by factor ~16 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-24 05:40 +0200
    Re: TREE_SRCU slows hotplug by factor ~16 Mike Galbraith <efault@gmx.de> - 2017-04-24 07:30 +0200
      Re: TREE_SRCU slows hotplug by factor ~16 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-24 08:30 +0200
        Re: TREE_SRCU slows hotplug by factor ~16 Mike Galbraith <efault@gmx.de> - 2017-04-24 09:40 +0200
          Re: TREE_SRCU slows hotplug by factor ~16 Mike Galbraith <efault@gmx.de> - 2017-04-24 10:50 +0200
          Re: TREE_SRCU slows hotplug by factor ~16 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-24 18:30 +0200

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