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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tony Lindgren <tony@atomide.com>, Mike Galbraith <efault@gmx.de>
Subject: Re: [RFC patch 1/2] sched: dynamically adapt granularity with nr_running
Date: Sun, 12 Sep 2010 16:39:25 -0400	[thread overview]
Message-ID: <20100912203925.GE32327@Krystal> (raw)
In-Reply-To: <1284282867.2251.84.camel@laptop>

* Peter Zijlstra (peterz@infradead.org) wrote:
> On Sun, 2010-09-12 at 11:06 +0200, Peter Zijlstra wrote:
> >  * is slice length, + is period length
> > 
> > Patch (sched_latency = 10, sched_min_gran = 10/3)
> > 
> > 
> > 30 |                             +
> >    |
> >    |
> >    |                          +
> >    |
> >    |
> >    |
> >    |
> >    |
> >    |
> > 20 |
> >    |
> >    |
> >    |
> >    |
> >    |
> >    |
> >    |
> >    |
> >    |
> > 10 |  *  +  +  +  +  +  +  +
> >    |
> >    |
> >    |
> >    |
> >    |     *
> >    |
> >    |        *  *              *  *  *  *  *  *
> >    |              *  *
> >    |                    *  *
> > 0  +---------------------------------------------------------
> >    0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 
> 
> 
> Vertical is time , horz is nr_running.
> 
> 
> Note how things fall of a cliff when nr_running goes from 8 to 9. Andrew
> usually kicks people in the teeth for phase change behaviour.

Please refer to my other email asking why your sched_latency = 10 rather than
what I see in sched_fair.c:

unsigned int sysctl_sched_latency = 6000000ULL;

I really might have missed something important there. Is this value recomputed
dynamically somewhere ?

Thanks,

Mathieu

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

  reply	other threads:[~2010-09-12 20:39 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-11 17:37 [RFC patch 0/2] sched: dynamically adapt granularity with nr_running Mathieu Desnoyers
2010-09-11 17:37 ` [RFC patch 1/2] " Mathieu Desnoyers
2010-09-11 18:57   ` Peter Zijlstra
2010-09-11 19:21     ` Linus Torvalds
2010-09-11 20:36       ` Peter Zijlstra
2010-09-11 20:45         ` Peter Zijlstra
2010-09-11 20:52           ` Linus Torvalds
2010-09-12  9:07             ` Peter Zijlstra
2010-09-11 20:48         ` Linus Torvalds
2010-09-12  9:06           ` Peter Zijlstra
2010-09-12  9:14             ` Peter Zijlstra
2010-09-12 20:39               ` Mathieu Desnoyers [this message]
2010-09-13 12:54                 ` Peter Zijlstra
2010-09-12 20:34             ` Mathieu Desnoyers
2010-09-13 12:53               ` Peter Zijlstra
2010-09-13  4:35             ` Mike Galbraith
2010-09-13  8:41               ` Peter Zijlstra
2010-09-13 11:22                 ` Ingo Molnar
2010-09-13 13:52                 ` Steven Rostedt
2010-09-13 13:54                   ` Peter Zijlstra
2010-09-13 14:02                     ` Peter Zijlstra
2010-09-13 14:21                       ` Ingo Molnar
2010-09-11 20:52         ` Mathieu Desnoyers
2010-09-11 19:57     ` Mathieu Desnoyers
2010-09-12 10:41       ` Peter Zijlstra
2010-09-12 20:37         ` Mathieu Desnoyers
2010-09-13 12:53           ` Peter Zijlstra
2010-09-13 13:15             ` Peter Zijlstra
2010-09-13 13:56               ` Mathieu Desnoyers
2010-09-13 14:16                 ` Peter Zijlstra
2010-09-13 14:43                   ` Steven Rostedt
2010-09-13 15:25                     ` Mathieu Desnoyers
2010-09-13 15:39                       ` Steven Rostedt
2010-09-13 16:16                   ` [RFC PATCH] check_preempt_tick should not compare vruntime with wall time Mathieu Desnoyers
2010-09-13 16:36                     ` Linus Torvalds
2010-09-13 17:45                       ` Mathieu Desnoyers
2010-09-13 17:51                         ` Linus Torvalds
2010-09-13 18:01                           ` Mathieu Desnoyers
2010-09-13 18:10                           ` Steven Rostedt
2010-09-13 18:03                         ` Ingo Molnar
2010-09-13 18:19                           ` Mathieu Desnoyers
2010-09-13 18:23                             ` [PATCH] sched: Improve latencies under load by decreasing minimum scheduling granularity Ingo Molnar
2010-09-13 18:28                               ` Joe Perches
2010-09-13 19:44                               ` Linus Torvalds
2010-09-13 20:00                                 ` Ingo Molnar
2010-09-13 18:19                         ` [RFC PATCH] check_preempt_tick should not compare vruntime with wall time Ingo Molnar
2010-09-13 17:36                     ` Ingo Molnar
2010-09-13 17:56                       ` Mathieu Desnoyers
2010-09-14  2:10                     ` Mike Galbraith
2010-09-13 14:44                 ` [RFC patch 1/2] sched: dynamically adapt granularity with nr_running Mike Galbraith
     [not found]               ` <1284386179.10436.6.camel@marge.simson.net>
2010-09-13 15:53                 ` Peter Zijlstra
2010-09-13 18:04                   ` [RFC][PATCH] sched: Improve tick preemption Peter Zijlstra
2010-09-14  2:27                   ` [RFC patch 1/2] sched: dynamically adapt granularity with nr_running Mike Galbraith
2010-09-12  6:14   ` Ingo Molnar
2010-09-12  7:21     ` Mike Galbraith
2010-09-12 18:16       ` Mathieu Desnoyers
2010-09-13  4:13         ` Mike Galbraith
2010-09-13  6:41           ` Ingo Molnar
2010-09-13  7:08             ` Mike Galbraith
2010-09-13  7:35               ` Mike Galbraith
2010-09-13  8:35               ` Peter Zijlstra
2010-09-13  9:16                 ` Mike Galbraith
2010-09-13  9:37                   ` Peter Zijlstra
2010-09-13  9:50                     ` Mike Galbraith
2010-09-13  9:55                       ` Peter Zijlstra
2010-09-13 10:06                         ` Mike Galbraith
2010-09-13 10:45                         ` Peter Zijlstra
2010-09-13 11:43                           ` Peter Zijlstra
2010-09-13 11:49                             ` Peter Zijlstra
2010-09-13 12:32                             ` Mike Galbraith
2010-09-13 20:19             ` Mathieu Desnoyers
2010-09-13 20:56               ` Mathieu Desnoyers
2010-09-12 18:13     ` Mathieu Desnoyers
2010-09-12 23:44       ` Mathieu Desnoyers
2010-09-11 17:37 ` [RFC patch 2/2] sched: sleepers coarse granularity on wakeup Mathieu Desnoyers
2010-09-12 12:44 ` [RFC patch 0/2] sched: dynamically adapt granularity with nr_running Peter Zijlstra

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