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From: Josef Bacik <jbacik@fb.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: <riel@redhat.com>, <mingo@redhat.com>,
	<linux-kernel@vger.kernel.org>, <umgwanakikbuti@gmail.com>,
	<morten.rasmussen@arm.com>, kernel-team <Kernel-team@fb.com>
Subject: Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for BALANCE_WAKE
Date: Mon, 1 Jun 2015 15:38:16 -0400	[thread overview]
Message-ID: <556CB4A8.1050509@fb.com> (raw)
In-Reply-To: <5568D43D.20703@fb.com>

On 05/29/2015 05:03 PM, Josef Bacik wrote:
> On 05/28/2015 07:05 AM, Peter Zijlstra wrote:
>>
>> So maybe you want something like the below; that cures the thing Morten
>> raised, and we continue looking for sd, even after we found affine_sd.
>>
>> It also avoids the pointless idle_cpu() check Mike raised by making
>> select_idle_sibling() return -1 if it doesn't find anything.
>>
>> Then it continues doing the full balance IFF sd was set, which is keyed
>> off of sd->flags.
>>
>> And note (as Mike already said), BALANCE_WAKE does _NOT_ look for idle
>> CPUs, it looks for the least loaded CPU. And its damn expensive.
>>
>>
>> Rewriting this entire thing is somewhere on the todo list :/
>>
>

Ok I got this patch to give me the same performance as all our other 
crap, just need to apply this incremental


diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b71eb2b..e11cfec 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4761,13 +4761,10 @@ select_task_rq_fair(struct task_struct *p, int 
prev_cpu, int sd_flag, int wake_f

  		if (tmp->flags & sd_flag)
  			sd = tmp;
-		else if (!want_affine || (want_affine && affine_sd))
-			break;
  	}

  	if (affine_sd && cpu != prev_cpu && wake_affine(affine_sd, p, sync)) {
  		prev_cpu = cpu;
-		sd = NULL; /* WAKE_AFFINE trumps BALANCE_WAKE */
  	}

  	if (sd_flag & SD_BALANCE_WAKE) {

And everything works fine.  Does that seem reasonable?  Thanks,

Josef

  parent reply	other threads:[~2015-06-01 19:39 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-27 21:22 [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for BALANCE_WAKE Josef Bacik
2015-05-28  3:46 ` Mike Galbraith
2015-05-28  9:49   ` Morten Rasmussen
2015-05-28 10:57     ` Mike Galbraith
2015-05-28 11:48       ` Morten Rasmussen
2015-05-28 11:49         ` Mike Galbraith
2015-05-28 10:21 ` Peter Zijlstra
2015-05-28 11:05   ` Peter Zijlstra
2015-05-28 14:27     ` Josef Bacik
2015-05-29 21:03     ` Josef Bacik
2015-05-30  3:55       ` Mike Galbraith
2015-06-01 19:38       ` Josef Bacik [this message]
2015-06-01 20:42         ` Peter Zijlstra
2015-06-01 21:03           ` Josef Bacik
2015-06-02 17:12           ` Josef Bacik
2015-06-03 14:12             ` Rik van Riel
2015-06-03 14:24               ` Peter Zijlstra
2015-06-03 14:49                 ` Josef Bacik
2015-06-03 15:30                 ` Mike Galbraith
2015-06-03 15:57                   ` Josef Bacik
2015-06-03 16:53                     ` Mike Galbraith
2015-06-03 17:16                       ` Josef Bacik
2015-06-03 17:43                         ` Mike Galbraith
2015-06-03 20:34                           ` Josef Bacik
2015-06-04  4:52                             ` Mike Galbraith
2015-06-01 22:15         ` Rik van Riel
2015-06-11 20:33     ` Josef Bacik
2015-06-12  3:42       ` Rik van Riel
2015-06-12  5:35     ` Mike Galbraith
2015-06-17 18:06       ` Josef Bacik
2015-06-18  0:55         ` Mike Galbraith
2015-06-18  3:46           ` Josef Bacik
2015-06-18  4:12             ` Mike Galbraith
2015-07-02 17:44               ` Josef Bacik
2015-07-03  6:40                 ` Mike Galbraith
2015-07-03  9:29                   ` Mike Galbraith
2015-07-04 15:57                   ` Mike Galbraith
2015-07-05  7:17                     ` Mike Galbraith
2015-07-06  5:13                       ` Mike Galbraith
2015-07-06 14:34                         ` Josef Bacik
2015-07-06 18:36                           ` Mike Galbraith
2015-07-06 19:41                             ` Josef Bacik
2015-07-07  4:01                               ` Mike Galbraith
2015-07-07  9:43                                 ` [patch] " Mike Galbraith
2015-07-07 13:40                                   ` Josef Bacik
2015-07-07 15:24                                     ` Mike Galbraith
2015-07-07 17:06                                   ` Josef Bacik
2015-07-08  6:13                                     ` [patch] sched: beef up wake_wide() Mike Galbraith
2015-07-09 13:26                                       ` Peter Zijlstra
2015-07-09 14:07                                         ` Mike Galbraith
2015-07-09 14:46                                           ` Mike Galbraith
2015-07-10  5:19                                         ` Mike Galbraith
2015-07-10 13:41                                           ` Josef Bacik
2015-07-10 20:59                                           ` Josef Bacik
2015-07-11  3:11                                             ` Mike Galbraith
2015-07-13 13:53                                               ` Josef Bacik
2015-07-14 11:19                                               ` Peter Zijlstra
2015-07-14 13:49                                                 ` Mike Galbraith
2015-07-14 14:07                                                   ` Peter Zijlstra
2015-07-14 14:17                                                     ` Mike Galbraith
2015-07-14 15:04                                                       ` Peter Zijlstra
2015-07-14 15:39                                                         ` Mike Galbraith
2015-07-14 16:01                                                           ` Josef Bacik
2015-07-14 17:59                                                             ` Mike Galbraith
2015-07-15 17:11                                                               ` Josef Bacik
2015-08-03 17:07                                                           ` [tip:sched/core] sched/fair: Beef " tip-bot for Mike Galbraith
2015-05-28 11:16   ` [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for BALANCE_WAKE Mike Galbraith
2015-05-28 11:49     ` Ingo Molnar
2015-05-28 12:15       ` Mike Galbraith
2015-05-28 12:19         ` Peter Zijlstra
2015-05-28 12:29           ` Ingo Molnar
2015-05-28 15:22           ` David Ahern
2015-05-28 11:55 ` Srikar Dronamraju

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