From: Mike Galbraith <efault@gmx.de>
To: Suresh Jayaraman <sjayaraman@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] sched: avoid huge bonus to sleepers on busy machines
Date: Mon, 04 Jan 2010 12:14:35 +0100 [thread overview]
Message-ID: <1262603675.9734.36.camel@marge.simson.net> (raw)
In-Reply-To: <1262596842-17392-1-git-send-email-sjayaraman@suse.de>
On Mon, 2010-01-04 at 14:50 +0530, Suresh Jayaraman wrote:
> As I understand the idea of sleeper fairness is to consider sleeping tasks
> similar to the ones on the runqueue and credit the sleepers in a way that it
> would get CPU as if it were running.
>
> Currently, when fair sleepers are enabled, the task that was sleeping seem to
> get a bonus of cfs_rq->min_vruntime - sched_latency (in most cases). While with
> gentle fair sleepers this effect was reduced to half, there still remains a
> chance that on busy machines with more number of tasks, the sleepers might get
> a huge undue bonus.
There is no bonus. Sleepers simply get to keep some of their lag, but
any lag beyond sched_latency is trashed in the interest of reasonable
latency for non-sleepers as the sleeper preempts and tries to catch up.
-Mike
next prev parent reply other threads:[~2010-01-04 11:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-04 9:20 [RFC][PATCH] sched: avoid huge bonus to sleepers on busy machines Suresh Jayaraman
2010-01-04 11:14 ` Mike Galbraith [this message]
2010-01-04 12:02 ` Suresh Jayaraman
2010-01-04 12:30 ` Mike Galbraith
2010-01-04 12:36 ` Peter Zijlstra
2010-01-04 12:49 ` Mike Galbraith
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