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From: Yuyang Du <yuyang.du@intel.com>
To: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [rfc patch] sched/fair: Use instantaneous load for fork/exec balancing
Date: Wed, 15 Jun 2016 06:42:18 +0800	[thread overview]
Message-ID: <20160614224218.GK8105@intel.com> (raw)
In-Reply-To: <1465891111.1694.13.camel@gmail.com>

On Tue, Jun 14, 2016 at 09:58:31AM +0200, Mike Galbraith wrote:
> SUSE's regression testing noticed that...
> 
> 0905f04eb21f sched/fair: Fix new task's load avg removed from source CPU in wake_up_new_task()
> 
> ...introduced a hackbench regression, and indeed it does.  I think this
> regression has more to do with randomness than anything else, but in
> general...
> 
> While averaging calms down load balancing, helping to keep migrations
> down to a dull roar, it's not completely wonderful when it comes to
> things that live in the here and now, hackbench being one such.
> 
> time sh -c 'for i in `seq 1000`; do hackbench -p -P > /dev/null; done'
> 
> real    0m55.397s
> user    0m8.320s
> sys     5m40.789s
> 
> echo LB_INSTANTANEOUS_LOAD > /sys/kernel/debug/sched_features
> 
> real    0m48.049s
> user    0m6.510s
> sys     5m6.291s
> 
> Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>

I am entirely for giving it a "clear unadulterated reality", and even
more for it an option.

Reviewed-by: Yuyang Du <yuyang.du@intel.com>

  parent reply	other threads:[~2016-06-15  6:39 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-14  7:58 [rfc patch] sched/fair: Use instantaneous load for fork/exec balancing Mike Galbraith
2016-06-14 14:14 ` Dietmar Eggemann
2016-06-14 16:40   ` Mike Galbraith
2016-06-15 15:32     ` Dietmar Eggemann
2016-06-15 16:03       ` Mike Galbraith
2016-06-15 19:03         ` Dietmar Eggemann
2016-06-16  3:33           ` Mike Galbraith
2016-06-16  9:01             ` Dietmar Eggemann
2016-07-04 15:04       ` Matt Fleming
2016-07-04 17:43         ` Mike Galbraith
2016-07-06 11:45           ` Matt Fleming
2016-07-06 12:21             ` Mike Galbraith
2016-07-11  8:58         ` Dietmar Eggemann
2016-07-12 11:14           ` Matt Fleming
2016-06-14 22:42 ` Yuyang Du [this message]
2016-06-15  7:01   ` Mike Galbraith
2016-06-16 11:46     ` [patch] sched/fair: Use instantaneous load in wakeup paths Mike Galbraith
2016-06-16 12:04       ` Mike Galbraith
2016-06-16 12:41         ` Mike Galbraith
2016-06-17  6:21           ` Mike Galbraith
2016-06-17 10:55             ` Dietmar Eggemann
2016-06-17 13:57               ` Mike Galbraith

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