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Groups > linux.kernel > #1443480

Re: Severe performance regression w/ 4.4+ on Android due to cgroup locking changes

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: Severe performance regression w/ 4.4+ on Android due to cgroup locking changes
Date 2016-07-14 16:20 +0200
Message-ID <rUPEC-2l6-33@gated-at.bofh.it> (permalink)
References (4 earlier) <rUyNs-7VU-11@gated-at.bofh.it> <rUyX7-7ZC-1@gated-at.bofh.it> <rUzgu-87F-9@gated-at.bofh.it> <rUzqa-8bo-19@gated-at.bofh.it> <rUOIy-1JY-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Thu, Jul 14, 2016 at 03:18:09PM +0200, Peter Zijlstra wrote:
> On Wed, Jul 13, 2016 at 10:51:02PM +0200, Peter Zijlstra wrote:
> > So, IIRC, the trade-off is a full memory barrier in read_lock and
> > read_unlock() vs sync_sched() in write.
> > 
> > Full memory barriers are expensive and while the combined cost might
> > well exceed the cost of the sync_sched() it doesn't suffer the latency
> > issues.
> > 
> > Not sure if we can frob the two in a single codebase, but I can have a
> > poke if Oleg or Paul doesn't beat me to it.
> 
> OK, not too horrible if I say so myself :-)
> 
> The below is a compile tested only first draft so far. I'll go give it
> some runtime next.

Doesn't explode if I run:

root@ivb-ep:/cgroup# mkdir ponies; for ((i=0; i<60; i++)) ; do while :; do echo $$ > tasks; echo $$ > ponies/tasks ; done & done

with cgroup using either READER or WRITER bias.

So passes light torture.

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Thread

Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-13 02:10 +0200
  Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-13 10:30 +0200
    Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-13 16:50 +0200
      Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-13 20:40 +0200
  Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-13 20:30 +0200
    Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-13 20:40 +0200
      Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-13 22:20 +0200
        Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-13 22:30 +0200
          Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-13 22:50 +0200
            Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-13 23:00 +0200
              Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-13 23:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-13 23:20 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-13 23:50 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-13 23:50 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-14 00:20 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-14 00:40 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-14 01:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-14 01:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-14 13:40 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 14:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-14 14:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 14:30 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-14 17:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-14 17:30 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 18:40 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Oleg Nesterov <oleg@redhat.com> - 2016-07-14 19:40 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-14 19:00 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-14 00:30 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-14 00:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-14 00:40 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 09:00 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-14 13:30 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 14:20 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-14 17:20 +0200
              Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-13 23:10 +0200
              Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-13 23:10 +0200
              Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 15:20 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 16:20 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Oleg Nesterov <oleg@redhat.com> - 2016-07-14 17:00 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 18:20 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 18:40 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Oleg Nesterov <oleg@redhat.com> - 2016-07-14 19:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-14 18:30 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 18:50 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-14 19:20 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-14 18:50 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 18:50 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-14 19:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Oleg Nesterov <oleg@redhat.com> - 2016-07-14 19:20 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-14 19:40 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Oleg Nesterov <oleg@redhat.com> - 2016-07-14 19:50 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-14 20:00 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Oleg Nesterov <oleg@redhat.com> - 2016-07-14 20:10 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 20:40 +0200
                Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-14 21:40 +0200
            Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-13 23:00 +0200
          Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Peter Zijlstra <peterz@infradead.org> - 2016-07-13 23:00 +0200
            Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-13 23:10 +0200
          Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-13 23:00 +0200
            Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Dmitry Shmidt <dimitrysh@google.com> - 2016-07-13 23:10 +0200
              Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-07-13 23:10 +0200
              Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-13 23:10 +0200
      Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes John Stultz <john.stultz@linaro.org> - 2016-07-13 22:20 +0200
      Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Dmitry Shmidt <dimitrysh@google.com> - 2016-07-13 22:40 +0200
    Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Colin Cross <ccross@google.com> - 2016-07-13 22:50 +0200
      Re: Severe performance regression w/ 4.4+ on Android due to cgroup  locking changes Tejun Heo <tj@kernel.org> - 2016-07-13 23:00 +0200

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