From: Mike Galbraith <mgalbraith@suse.de>
To: Yuyang Du <yuyang.du@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Chris Mason <clm@fb.com>,
Ingo Molnar <mingo@kernel.org>,
Matt Fleming <matt@codeblueprint.co.uk>,
linux-kernel@vger.kernel.org
Subject: Re: sched: tweak select_idle_sibling to look for idle threads
Date: Mon, 09 May 2016 11:39:05 +0200 [thread overview]
Message-ID: <1462786745.3803.181.camel@suse.de> (raw)
In-Reply-To: <20160509011311.GQ16093@intel.com>
On Mon, 2016-05-09 at 09:13 +0800, Yuyang Du wrote:
> On Mon, May 09, 2016 at 09:44:13AM +0200, Mike Galbraith wrote:
> > In a perfect world, running only Chris' benchmark on an otherwise idle
> > box, there would never _be_ any work to steal.
>
> What is the perfect world like? I don't get what you mean.
In a perfect world from this benchmark's perspective, when you fork or
wake while box is underutilized, wakee/child lands on an idle CPU. To
this benchmark, anything else is broken.
> > In the real world, we
> > smooth utilization, optimistically peek at this/that, and intentionally
> > throttle idle balancing (etc etc), which adds up to an imperfect world
> > for this (based on real world load) benchmark.
>
> So, is this a shout-out: these parts should be coordinated better?
Switching to instantaneous load along with the cpu reservation hackery
made Chris's benchmark a happy camper. Is that the answer? Nope, just
verification of the where the problem lives.
> > > En... should we try remove recording last_wakee?
> >
> > The more the merrier, go for it! :)
>
> Nuh, really, this heuristic is too heuristic, :)
> The totality of all possible cases is scary.
Well, make it better. The author provided evidence when it was born.
-Mike
next prev parent reply other threads:[~2016-05-09 9:39 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-05 18:08 [PATCH RFC] select_idle_sibling experiments Chris Mason
2016-04-05 18:43 ` Bastien Bastien Philbert
2016-04-05 19:28 ` Chris Mason
2016-04-05 20:03 ` Matt Fleming
2016-04-05 21:05 ` Bastien Philbert
2016-04-06 0:44 ` Chris Mason
2016-04-06 7:27 ` Mike Galbraith
2016-04-06 13:36 ` Chris Mason
2016-04-09 17:30 ` Chris Mason
2016-04-12 21:45 ` Matt Fleming
2016-04-13 3:40 ` Mike Galbraith
2016-04-13 15:54 ` Chris Mason
2016-04-28 12:00 ` Peter Zijlstra
2016-04-28 13:17 ` Mike Galbraith
2016-05-02 5:35 ` Mike Galbraith
2016-04-07 15:17 ` Chris Mason
2016-04-09 19:05 ` sched: tweak select_idle_sibling to look for idle threads Chris Mason
2016-04-10 10:04 ` Mike Galbraith
2016-04-10 12:35 ` Chris Mason
2016-04-10 12:46 ` Mike Galbraith
2016-04-10 19:55 ` Chris Mason
2016-04-11 4:54 ` Mike Galbraith
2016-04-12 0:30 ` Chris Mason
2016-04-12 4:44 ` Mike Galbraith
2016-04-12 13:27 ` Chris Mason
2016-04-12 18:16 ` Mike Galbraith
2016-04-12 20:07 ` Chris Mason
2016-04-13 3:18 ` Mike Galbraith
2016-04-13 13:44 ` Chris Mason
2016-04-13 14:22 ` Mike Galbraith
2016-04-13 14:36 ` Chris Mason
2016-04-13 15:05 ` Mike Galbraith
2016-04-13 15:34 ` Mike Galbraith
2016-04-30 12:47 ` Peter Zijlstra
2016-05-01 7:12 ` Mike Galbraith
2016-05-01 8:53 ` Peter Zijlstra
2016-05-01 9:20 ` Mike Galbraith
2016-05-07 1:24 ` Yuyang Du
2016-05-08 8:08 ` Mike Galbraith
2016-05-08 18:57 ` Yuyang Du
2016-05-09 3:45 ` Mike Galbraith
2016-05-08 20:22 ` Yuyang Du
2016-05-09 7:44 ` Mike Galbraith
2016-05-09 1:13 ` Yuyang Du
2016-05-09 9:39 ` Mike Galbraith [this message]
2016-05-09 23:26 ` Yuyang Du
2016-05-10 7:49 ` Mike Galbraith
2016-05-10 15:26 ` Mike Galbraith
2016-05-10 19:16 ` Yuyang Du
2016-05-11 4:17 ` Mike Galbraith
2016-05-11 1:23 ` Yuyang Du
2016-05-11 9:56 ` Mike Galbraith
2016-05-18 6:41 ` Mike Galbraith
2016-05-09 3:52 ` Mike Galbraith
2016-05-08 20:31 ` Yuyang Du
2016-05-02 8:46 ` Peter Zijlstra
2016-05-02 14:50 ` Mike Galbraith
2016-05-02 14:58 ` Peter Zijlstra
2016-05-02 15:47 ` Chris Mason
2016-05-03 14:32 ` Peter Zijlstra
2016-05-03 15:11 ` Chris Mason
2016-05-04 10:37 ` Peter Zijlstra
2016-05-04 15:31 ` Peter Zijlstra
2016-05-05 22:03 ` Matt Fleming
2016-05-06 18:54 ` Mike Galbraith
2016-05-09 8:33 ` Peter Zijlstra
2016-05-09 8:56 ` Mike Galbraith
2016-05-04 15:45 ` Peter Zijlstra
2016-05-04 17:46 ` Chris Mason
2016-05-05 9:33 ` Peter Zijlstra
2016-05-05 13:58 ` Chris Mason
2016-05-06 7:12 ` Peter Zijlstra
2016-05-06 17:27 ` Chris Mason
2016-05-06 7:25 ` Peter Zijlstra
2016-05-02 17:30 ` Mike Galbraith
2016-05-02 15:01 ` Peter Zijlstra
2016-05-02 16:04 ` Ingo Molnar
2016-05-03 11:31 ` Peter Zijlstra
2016-05-03 18:22 ` Peter Zijlstra
2016-05-02 15:10 ` Peter Zijlstra
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