From: Joe Korty <joe.korty@ccur.com>
To: Con Kolivas <kernel@kolivas.org>
Cc: steve.rotolo@ccur.com, linux-kernel@vger.kernel.org, bugsy@ccur.com
Subject: Re: SD_SHARE_CPUPOWER breaks scheduler fairness
Date: Wed, 1 Jun 2005 19:16:15 -0400 [thread overview]
Message-ID: <20050601231615.GA11301@tsunami.ccur.com> (raw)
In-Reply-To: <200506020737.20098.kernel@kolivas.org>
> On Thu, 2 Jun 2005 04:41, Steve Rotolo wrote:
> > I guess the bottom-line is: given N logical cpus, 1/N of all
> > SCHED_NORMAL tasks may get stuck on a sibling cpu with no chance to
> > run. All it takes is one spinning SCHED_FIFO task. Sounds like a bug.
>
> You're right, and excuse me for missing it. We have to let SCHED_NORMAL tasks
> run for some period with rt tasks. There shouldn't be any combination of
> mutually exclusive tasks for siblings.
>
> I'll work on something.
Wild thought: how about doing this for the sibling ...
rp->nr_running += SOME_BIG_NUMBER
when a SCHED_FIFO task starts running on some cpu, and
undo the above when the cpu is released. This fools
the load balancer into _gradually_ moving tasks off the
sibling, when the cpu is hogged by some SCHED_FIFO task,
but should have little effect if a SCHED_FIFO task takes
little cpu time.
Regards,
Joe
--
"Money can buy bandwidth, but latency is forever" -- John Mashey
next prev parent reply other threads:[~2005-06-01 23:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-31 17:46 SD_SHARE_CPUPOWER breaks scheduler fairness Steve Rotolo
2005-06-01 2:49 ` Con Kolivas
2005-06-01 14:29 ` Steve Rotolo
2005-06-01 14:47 ` Con Kolivas
2005-06-01 18:41 ` Steve Rotolo
2005-06-01 21:37 ` Con Kolivas
2005-06-01 21:54 ` Con Kolivas
2005-06-01 22:01 ` Steve Rotolo
2005-06-02 3:01 ` Con Kolivas
2005-06-01 23:16 ` Joe Korty [this message]
2005-06-01 23:25 ` Con Kolivas
2005-06-02 13:30 ` Steve Rotolo
2005-06-02 13:34 ` Con Kolivas
2005-06-02 15:48 ` Steve Rotolo
2005-06-03 0:43 ` [PATCH] SCHED: run SCHED_NORMAL tasks with real time tasks on SMT siblings Con Kolivas
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