From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: stephan.baerwolf@tu-ilmenau.de, linux-kernel@vger.kernel.org,
Ingo Molnar <mingo@elte.hu>,
ncrao@google.com
Subject: Re: sched: fix/optimise some issues
Date: Thu, 21 Jul 2011 03:00:09 +0200 [thread overview]
Message-ID: <1311210009.7746.37.camel@marge.simson.net> (raw)
In-Reply-To: <1311189090.29152.73.camel@twins>
On Wed, 2011-07-20 at 21:11 +0200, Peter Zijlstra wrote:
> On Wed, 2011-07-20 at 15:42 +0200, Stephan Bärwolf wrote:
> > In "check_preempt_tick()" (kernel/sched_fair.c:1093) a ulong
> > called "ideal_runtime" stores a timeslice of the current task
> > (scheduling entity). This time complies real cpu-time.
> >
> > At the end of the same function (nr_running > 1) this (real) time
> > is compared with a virtual-runtime-delta. Obviously the timeunits
> > (real vs. virtual) didn't fit.
> >
> > Using "wakeup_preempt_entity()" instead should fix this in a even
> > more general way.
(That's what I thought at first too)
> Hrm,. I'm fairly sure we did that on purpose and the thing that is
> missing is a big fat comment. People keep trying to fix that (me
> included).
>
> I'll try and dig up the why and such.
Better to just kill it outright. It's not doing that much anyway.
-Mike
next prev parent reply other threads:[~2011-07-21 1:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-20 13:42 sched: fix/optimise some issues Stephan Bärwolf
2011-07-20 19:11 ` Peter Zijlstra
2011-07-21 1:00 ` Mike Galbraith [this message]
2011-07-20 19:11 ` Peter Zijlstra
2011-07-20 19:11 ` Peter Zijlstra
2011-07-21 15:08 ` Peter Zijlstra
2011-07-21 16:36 ` Stephan Bärwolf
2011-07-21 16:32 ` Peter Zijlstra
2011-07-21 16:43 ` Peter Zijlstra
2011-07-21 16:51 ` Peter Zijlstra
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