Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for BALANCE_WAKE

From	Mike Galbraith <umgwanakikbuti@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for BALANCE_WAKE
Date	2015-06-03 17:40 +0200
Message-ID	<pxiVQ-5gl-9@gated-at.bofh.it> (permalink)
References	(4 earlier) <pwDJ0-2Pa-7@gated-at.bofh.it> <pwEOK-4uj-7@gated-at.bofh.it> <pwY14-7M5-23@gated-at.bofh.it> <pxhGp-3tO-9@gated-at.bofh.it> <pxhQ5-3FJ-1@gated-at.bofh.it>
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On Wed, 2015-06-03 at 16:24 +0200, Peter Zijlstra wrote:
> On Wed, 2015-06-03 at 10:12 -0400, Rik van Riel wrote:
> 
> > There is a policy vs mechanism thing here. Ingo and Peter
> > are worried about the overhead in the mechanism of finding
> > an idle CPU.  Your measurements show that the policy of
> > finding an idle CPU is the correct one.
> 
> For his workload; I'm sure I can find a workload where it hurts.
> 
> In fact, I'm fairly sure Mike knows one from the top of his head, seeing
> how he's the one playing about trying to shrink that idle search :-)

Like anything where scheduling latency doesn't heavily dominate.  Even
if searching were free, bounces aren't, even for the very light.

	-Mike

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Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for  BALANCE_WAKE Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-06-03 17:40 +0200
  Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for  BALANCE_WAKE Josef Bacik <jbacik@fb.com> - 2015-06-03 18:00 +0200
    Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for  BALANCE_WAKE Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-06-03 19:00 +0200
      Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for  BALANCE_WAKE Josef Bacik <jbacik@fb.com> - 2015-06-03 19:20 +0200

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