From: Mike Galbraith <efault@gmx.de>
To: Darren Hart <dvhart@linux.intel.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>,
richard.purdie@linuxfoundation.org
Subject: Re: [PATCH 1/2] sched: allow SCHED_BATCH to preempt SCHED_IDLE tasks
Date: Wed, 23 Feb 2011 06:31:58 +0100 [thread overview]
Message-ID: <1298439118.7856.80.camel@marge.simson.net> (raw)
In-Reply-To: <1298434854.7856.24.camel@marge.simson.net>
On Wed, 2011-02-23 at 05:20 +0100, Mike Galbraith wrote:
> On Tue, 2011-02-22 at 13:04 -0800, Darren Hart wrote:
> > Perform the test for SCHED_IDLE before testing for SCHED_BATCH (and ensure idle
> > tasks don't preempt idle tasks) so the non-interactive, but still important,
> > SCHED_BATCH tasks will run in favor of the very low priority SCHED_IDLE tasks.
>
> Yeah, that could be construed as a fairness fix for light SCHED_BATCH vs
> a heavy SCHED_IDLE. It should lower latencies for both when mixed.
Hm. Seems SCHED_IDLE _always_ being preempted is a potential terminal
starvation bug though, unless preempt_tick() checks spread to guarantee
that the preempted task will eventually get the CPU back, even in the
face of massive non-idle wakeup driven load.. which it does not. (idle
task holds resource?)
Maybe my imagination has had too much java though.
-Mike
next prev parent reply other threads:[~2011-02-23 5:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-22 21:04 [PATCH 0/2] sched: SCHED_BATCH fixes Darren Hart
2011-02-22 21:04 ` [PATCH 1/2] sched: allow SCHED_BATCH to preempt SCHED_IDLE tasks Darren Hart
2011-02-23 4:20 ` Mike Galbraith
2011-02-23 5:31 ` Mike Galbraith [this message]
2011-02-23 5:33 ` Darren Hart
2011-03-04 11:49 ` [tip:sched/core] sched: Allow " tip-bot for Darren Hart
2011-02-22 21:04 ` [PATCH 2/2] sched: allow users with rtprio rlimit to change from SCHED_IDLE policy Darren Hart
2011-02-23 11:03 ` Peter Zijlstra
2011-02-23 11:13 ` Ingo Molnar
2011-02-23 11:17 ` Peter Zijlstra
2011-02-23 11:35 ` Ingo Molnar
2011-02-23 15:52 ` Darren Hart
2011-02-23 16:00 ` Peter Zijlstra
2011-02-23 16:07 ` Darren Hart
2011-02-23 21:28 ` Darren Hart
2011-02-24 11:49 ` Peter Zijlstra
2011-03-04 11:49 ` [tip:sched/core] sched: Allow users with sufficient RLIMIT_NICE " tip-bot for Darren Hart
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