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Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable again and shut down on idle)

From Mike Galbraith <umgwanakikbuti@gmail.com>
Newsgroups linux.kernel
Subject Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable again and shut down on idle)
Date 2016-01-26 20:10 +0100
Message-ID <qVha3-8N-45@gated-at.bofh.it> (permalink)
References (11 earlier) <qUTKq-7UQ-17@gated-at.bofh.it> <qV1oB-4JB-1@gated-at.bofh.it> <qVeFd-6F7-21@gated-at.bofh.it> <qVfhV-7dM-31@gated-at.bofh.it> <qVgxl-83o-21@gated-at.bofh.it>
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On Tue, 2016-01-26 at 12:22 -0600, Christoph Lameter wrote:
> On Tue, 26 Jan 2016, Mike Galbraith wrote:
> 
> > On Tue, 2016-01-26 at 10:26 -0600, Christoph Lameter wrote:
> > > On Tue, 26 Jan 2016, Mike Galbraith wrote:
> > > 
> > > > > Why would the deferring cause this overhead?
> > > > 
> > > > Because we schedule to idle cores aggressively, thus we may pop
> > > > in and
> > > > out of idle at high frequency.
> > > 
> > > Whats the point of going idle if you have things to do soon?
> > 
> > When a task schedules off, how do you know it'll be back at all,
> > much
> > less soon?
> 
> Ok so you are running an artificial benchmark that always gets the
> system running again when it decides to go idle?

The benchmark does not alter the cycle expenditure per event.  The real
world will pay the toll less frequently than the artificial benchmark,
yes, but it will pay nonetheless, and for most, needlessly.  Or?

	-Mike

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Thread

Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Michal Hocko <mhocko@kernel.org> - 2016-01-20 15:40 +0100
  Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Sasha Levin <sasha.levin@oracle.com> - 2016-01-20 16:00 +0100
    Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Michal Hocko <mhocko@kernel.org> - 2016-01-20 16:20 +0100
      Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Christoph Lameter <cl@linux.com> - 2016-01-20 16:30 +0100
        Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Sasha Levin <sasha.levin@oracle.com> - 2016-01-20 17:00 +0100
          Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Christoph Lameter <cl@linux.com> - 2016-01-20 17:00 +0100
            Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Michal Hocko <mhocko@kernel.org> - 2016-01-20 22:30 +0100
              Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Christoph Lameter <cl@linux.com> - 2016-01-20 23:00 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Michal Hocko <mhocko@kernel.org> - 2016-01-21 09:30 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Christoph Lameter <cl@linux.com> - 2016-01-21 16:50 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Michal Hocko <mhocko@kernel.org> - 2016-01-21 18:00 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Christoph Lameter <cl@linux.com> - 2016-01-21 18:40 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Shiraz Hashim <shiraz.linux.kernel@gmail.com> - 2016-01-22 12:10 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Michal Hocko <mhocko@kernel.org> - 2016-01-22 15:10 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Christoph Lameter <cl@linux.com> - 2016-01-22 17:10 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Michal Hocko <mhocko@kernel.org> - 2016-01-22 17:20 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Christoph Lameter <cl@linux.com> - 2016-01-22 17:50 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Michal Hocko <mhocko@kernel.org> - 2016-01-22 18:20 +0100
                fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-23 17:30 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-24 01:40 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-24 03:50 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-24 04:50 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-24 06:40 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Michal Hocko <mhocko@kernel.org> - 2016-01-25 18:50 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-25 19:10 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Michal Hocko <mhocko@kernel.org> - 2016-01-25 21:20 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-26 17:30 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-26 19:40 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-26 19:50 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-26 20:30 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-27 04:20 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-27 05:20 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-27 17:30 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-26 19:40 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-26 03:20 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-26 03:30 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-26 17:30 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-26 18:40 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-26 19:20 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-26 17:30 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-26 18:10 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-26 19:30 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-26 20:10 +0100
                Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable  again and shut down on idle) Christoph Lameter <cl@linux.com> - 2016-01-26 20:30 +0100
                [PATCH] mm, vmstat: make quiet_vmstat lighter (was: Re: fast path  cycle muncher (vmstat: make vmstat_updater deferrable) again and shut down  on idle) Michal Hocko <mhocko@kernel.org> - 2016-01-27 17:50 +0100
                Re: [PATCH] mm, vmstat: make quiet_vmstat lighter (was: Re: fast  path cycle muncher (vmstat: make vmstat_updater deferrable) again and shut  down on idle) Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-01-27 18:10 +0100
                Re: [PATCH] mm, vmstat: make quiet_vmstat lighter (was: Re: fast  path cycle muncher (vmstat: make vmstat_updater deferrable) again and shut  down on idle) Christoph Lameter <cl@linux.com> - 2016-01-27 19:30 +0100
                Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Linus Torvalds <torvalds@linux-foundation.org> - 2016-01-24 18:00 +0100
  Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Christoph Lameter <cl@linux.com> - 2016-01-20 16:20 +0100
    Re: mm, vmstat: kernel BUG at mm/vmstat.c:1408! Michal Hocko <mhocko@kernel.org> - 2016-01-20 16:30 +0100

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