Re: [BUG nohz]: wrong user and system time accounting

From	Mike Galbraith <efault@gmx.de>
Newsgroups	linux.kernel
Subject	Re: [BUG nohz]: wrong user and system time accounting
Date	2017-03-30 15:40 +0200
Message-ID	<tqIsW-70Q-27@gated-at.bofh.it> (permalink)
References	(4 earlier) <tqseu-3C5-21@gated-at.bofh.it> <tqseu-3C5-19@gated-at.bofh.it> <tqzSG-Sh-31@gated-at.bofh.it> <tqHQd-6vZ-3@gated-at.bofh.it> <tqHZU-6On-9@gated-at.bofh.it>
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On Thu, 2017-03-30 at 09:02 -0400, Rik van Riel wrote:
> On Thu, 2017-03-30 at 14:51 +0200, Frederic Weisbecker wrote:

> > Also, why does it raise power consumption issues?
> 
> On a system without either nohz_full or nohz idle
> mode, skewed ticks result in CPU cores waking up
> at different times, and keeping an idle system
> consuming power for more time than it would if all
> the ticks happened simultaneously.

And if your server farm is mostly idle, that power savings may delay
your bankruptcy proceedings by a whole microsecond ;-)

Or more seriously, what skew does do on boxen of size X today is
something for perf to say.  At the time, removal was very bad for my 8
socket box, and allegedly caused huge SGI beasts in horrific pain.

	-Mike

Thread

Re: [BUG nohz]: wrong user and system time accounting Rik van Riel <riel@redhat.com> - 2017-03-27 19:40 +0200
  Re: [BUG nohz]: wrong user and system time accounting Wanpeng Li <kernellwp@gmail.com> - 2017-03-28 09:30 +0200
  Re: [BUG nohz]: wrong user and system time accounting Rik van Riel <riel@redhat.com> - 2017-03-28 23:10 +0200
    Re: [BUG nohz]: wrong user and system time accounting Luiz Capitulino <lcapitulino@redhat.com> - 2017-03-28 23:30 +0200
      Re: [BUG nohz]: wrong user and system time accounting Wanpeng Li <kernellwp@gmail.com> - 2017-03-29 12:00 +0200
        Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-03-29 15:00 +0200
  Re: [BUG nohz]: wrong user and system time accounting Rik van Riel <riel@redhat.com> - 2017-03-28 23:30 +0200
    Re: [BUG nohz]: wrong user and system time accounting Luiz Capitulino <lcapitulino@redhat.com> - 2017-03-28 23:40 +0200
  Re: [BUG nohz]: wrong user and system time accounting Rik van Riel <riel@redhat.com> - 2017-03-29 22:20 +0200
    Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-03-30 01:00 +0200
      Re: [BUG nohz]: wrong user and system time accounting Rik van Riel <riel@redhat.com> - 2017-03-30 15:00 +0200
    Re: [BUG nohz]: wrong user and system time accounting Wanpeng Li <kernellwp@gmail.com> - 2017-03-30 04:00 +0200
      Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-03-30 14:50 +0200
        Re: [BUG nohz]: wrong user and system time accounting Mike Galbraith <efault@gmx.de> - 2017-03-30 15:20 +0200
    Re: [BUG nohz]: wrong user and system time accounting Mike Galbraith <efault@gmx.de> - 2017-03-30 06:30 +0200
      Re: [BUG nohz]: wrong user and system time accounting Wanpeng Li <kernellwp@gmail.com> - 2017-03-30 08:50 +0200
        Re: [BUG nohz]: wrong user and system time accounting Wanpeng Li <kernellwp@gmail.com> - 2017-03-30 14:00 +0200
          Re: [BUG nohz]: wrong user and system time accounting Mike Galbraith <efault@gmx.de> - 2017-03-30 14:40 +0200
        Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-03-30 15:40 +0200
          Re: [BUG nohz]: wrong user and system time accounting Wanpeng Li <kernellwp@gmail.com> - 2017-03-30 16:10 +0200
            Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-03-30 16:30 +0200
              Re: [BUG nohz]: wrong user and system time accounting Luiz Capitulino <lcapitulino@redhat.com> - 2017-03-30 23:30 +0200
                Re: [BUG nohz]: wrong user and system time accounting Luiz Capitulino <lcapitulino@redhat.com> - 2017-03-31 22:10 +0200
                Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-04-01 01:30 +0200
                Re: [BUG nohz]: wrong user and system time accounting Luiz Capitulino <lcapitulino@redhat.com> - 2017-04-01 05:20 +0200
                Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-04-03 17:30 +0200
                Re: [BUG nohz]: wrong user and system time accounting Luiz Capitulino <lcapitulino@redhat.com> - 2017-04-03 21:10 +0200
                Re: [BUG nohz]: wrong user and system time accounting Luiz Capitulino <lcapitulino@redhat.com> - 2017-04-04 20:10 +0200
                Re: [BUG nohz]: wrong user and system time accounting Rik van Riel <riel@redhat.com> - 2017-04-05 16:30 +0200
      Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-03-30 15:00 +0200
        Re: [BUG nohz]: wrong user and system time accounting Rik van Riel <riel@redhat.com> - 2017-03-30 15:10 +0200
          Re: [BUG nohz]: wrong user and system time accounting Mike Galbraith <efault@gmx.de> - 2017-03-30 15:40 +0200
            Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-04-03 16:50 +0200
              Re: [BUG nohz]: wrong user and system time accounting Mike Galbraith <efault@gmx.de> - 2017-04-04 09:40 +0200
          Re: [BUG nohz]: wrong user and system time accounting Frederic Weisbecker <fweisbec@gmail.com> - 2017-03-30 15:50 +0200
  Re: [BUG nohz]: wrong user and system time accounting Wanpeng Li <kernellwp@gmail.com> - 2017-03-30 00:50 +0200
    Re: [BUG nohz]: wrong user and system time accounting Luiz Capitulino <lcapitulino@redhat.com> - 2017-03-30 04:20 +0200
      Re: [BUG nohz]: wrong user and system time accounting Wanpeng Li <kernellwp@gmail.com> - 2017-03-30 14:30 +0200

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