From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: paul.szabo@sydney.edu.au
Cc: linux-kernel@vger.kernel.org
Subject: Re: CFS scheduler unfairly prefers pinned tasks
Date: Tue, 06 Oct 2015 14:17:18 +0200 [thread overview]
Message-ID: <1444133838.2832.141.camel@gmail.com> (raw)
In-Reply-To: <201510061006.t96A69I8007672@como.maths.usyd.edu.au>
On Tue, 2015-10-06 at 21:06 +1100, paul.szabo@sydney.edu.au wrote:
> And further... the CFS is meant to be fair, using things like vruntime
> to preempt, and throttling. Why are those pinned tasks not preempted or
> throttled?
Imagine you own a 8192 CPU box for a moment, all CPUs having one pinned
task, plus one extra unpinned task, and ponder what would have to happen
in order to meet your utilization expectation. <time passes> Right.
What you're seeing is not a bug. No task can occupy more than one CPU
at a time, making space reservation on multiple CPUs a very bad idea.
-Mike
next prev parent reply other threads:[~2015-10-06 12:17 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-05 21:48 CFS scheduler unfairly prefers pinned tasks paul.szabo
2015-10-06 2:45 ` Mike Galbraith
2015-10-06 10:06 ` paul.szabo
2015-10-06 12:17 ` Mike Galbraith [this message]
2015-10-06 20:44 ` paul.szabo
2015-10-07 1:28 ` Mike Galbraith
2015-10-08 8:19 ` Mike Galbraith
2015-10-08 10:54 ` paul.szabo
2015-10-08 11:19 ` Peter Zijlstra
2015-10-10 13:22 ` [patch] sched: disable task group re-weighting on the desktop Mike Galbraith
2015-10-10 14:03 ` kbuild test robot
2015-10-10 14:41 ` Mike Galbraith
2015-10-10 17:01 ` Peter Zijlstra
2015-10-10 17:13 ` Peter Zijlstra
2015-10-11 2:25 ` Mike Galbraith
2015-10-11 17:42 ` 4.3 group scheduling regression Mike Galbraith
2015-10-12 7:23 ` Peter Zijlstra
2015-10-12 7:44 ` Mike Galbraith
2015-10-12 8:04 ` Peter Zijlstra
2015-10-12 0:53 ` Yuyang Du
2015-10-12 9:12 ` Peter Zijlstra
2015-10-12 2:12 ` Yuyang Du
2015-10-12 10:23 ` Mike Galbraith
2015-10-12 19:55 ` Yuyang Du
2015-10-13 4:08 ` Mike Galbraith
2015-10-12 20:42 ` Yuyang Du
2015-10-13 8:06 ` Peter Zijlstra
2015-10-13 0:35 ` Yuyang Du
2015-10-13 8:10 ` Peter Zijlstra
2015-10-13 0:37 ` Yuyang Du
2015-10-12 11:47 ` Peter Zijlstra
2015-10-12 19:32 ` Yuyang Du
2015-10-13 8:07 ` Peter Zijlstra
2015-10-13 2:22 ` Mike Galbraith
2015-10-12 8:48 ` Mike Galbraith
2015-10-10 20:14 ` [patch] sched: disable task group re-weighting on the desktop paul.szabo
2015-10-11 2:38 ` Mike Galbraith
2015-10-11 9:25 ` paul.szabo
2015-10-11 12:49 ` Mike Galbraith
2015-10-11 19:46 ` paul.szabo
2015-10-12 1:59 ` Mike Galbraith
2015-10-08 14:25 ` CFS scheduler unfairly prefers pinned tasks Mike Galbraith
2015-10-08 21:55 ` paul.szabo
2015-10-09 1:56 ` Mike Galbraith
2015-10-09 2:40 ` Mike Galbraith
2015-10-11 9:43 ` paul.szabo
2015-10-10 3:59 ` Wanpeng Li
2015-10-10 7:58 ` Wanpeng Li
-- strict thread matches above, loose matches on Subject: below --
2015-10-11 20:59 paul.szabo
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