From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: linux-kernel@vger.kernel.org, morten.rasmussen@arm.com,
mingo@kernel.org, peterz@infradead.org,
george.mccollister@gmail.com, ktkhai@parallels.com
Subject: Re: [PATCH RFC/TEST] sched: make sync affine wakeups work
Date: Fri, 02 May 2014 08:51:09 +0200 [thread overview]
Message-ID: <1399013469.5233.85.camel@marge.simpson.net> (raw)
In-Reply-To: <1399012619.5233.76.camel@marge.simpson.net>
On Fri, 2014-05-02 at 08:36 +0200, Mike Galbraith wrote:
> Reason why is that case was on a box where FAIR_SLEEPERS is disabled by
> default, meaning there is no such thing as wakeup preemption. Guess
> what happens when you don't have shared LLC for a fast/light wakee to
> escape to when the waker is a pig. The worst thing possible in that
> case is to wake affine. Leave the poor thing wherever it was, else it
> will take a latency hit that need not have been.
Oh yeah, and you'll see similar issues playing with kvm. No escape
routes are available, as no llc domain exists. Globally do a sync
wakeup CPU affine, and for some loads that will induce massive wreckage
where as If select_isle_sibling() had been there to save the day, all
would have been peachy. Is it good, or is it evil... depends.
-Mike
next prev parent reply other threads:[~2014-05-02 6:51 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-02 4:42 Rik van Riel
2014-05-02 5:32 ` Mike Galbraith
2014-05-02 5:41 ` Mike Galbraith
2014-05-02 5:58 ` Mike Galbraith
2014-05-02 6:08 ` Rik van Riel
2014-05-02 6:36 ` Mike Galbraith
2014-05-02 6:51 ` Mike Galbraith [this message]
2014-05-02 6:13 ` Mike Galbraith
2014-05-02 6:30 ` Rik van Riel
2014-05-02 7:37 ` Mike Galbraith
2014-05-02 10:56 ` Rik van Riel
2014-05-02 11:27 ` Mike Galbraith
2014-05-02 12:51 ` Mike Galbraith
[not found] ` <5363B793.9010208@redhat.com>
2014-05-06 11:54 ` Peter Zijlstra
2014-05-06 20:19 ` Rik van Riel
2014-05-06 20:39 ` Peter Zijlstra
2014-05-06 23:46 ` Rik van Riel
2014-05-09 2:20 ` Rik van Riel
2014-05-09 5:27 ` [PATCH] sched: wake up task on prev_cpu if not in SD_WAKE_AFFINE domain with cpu Rik van Riel
2014-05-09 6:04 ` [PATCH] sched: clean up select_task_rq_fair conditionals and indentation Rik van Riel
2014-05-09 7:34 ` [PATCH] sched: wake up task on prev_cpu if not in SD_WAKE_AFFINE domain with cpu Mike Galbraith
2014-05-09 14:22 ` Rik van Riel
2014-05-09 15:24 ` Mike Galbraith
2014-05-09 15:24 ` Rik van Riel
2014-05-09 17:55 ` Mike Galbraith
2014-05-09 18:16 ` Rik van Riel
2014-05-10 3:54 ` Mike Galbraith
2014-05-13 14:08 ` Rik van Riel
2014-05-14 4:08 ` Mike Galbraith
2014-05-14 15:40 ` [PATCH] sched: call select_idle_sibling when not affine_sd Rik van Riel
2014-05-14 15:45 ` Peter Zijlstra
2014-05-19 13:08 ` [tip:sched/core] " tip-bot for Rik van Riel
2014-05-22 12:27 ` [tip:sched/core] sched: Call select_idle_sibling() " tip-bot for Rik van Riel
2014-05-04 11:44 ` [PATCH RFC/TEST] sched: make sync affine wakeups work Preeti Murthy
2014-05-04 12:04 ` Mike Galbraith
2014-05-05 4:38 ` Preeti U Murthy
2014-05-04 12:41 ` Rik van Riel
2014-05-05 4:50 ` Preeti U Murthy
2014-05-05 6:43 ` Preeti U Murthy
2014-05-05 11:28 ` Rik van Riel
2014-05-06 13:26 ` Peter Zijlstra
2014-05-06 13:25 ` Peter Zijlstra
2014-05-06 20:20 ` Rik van Riel
2014-05-06 20:41 ` Peter Zijlstra
2014-05-07 12:17 ` Ingo Molnar
2014-05-06 11:56 ` Peter Zijlstra
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