From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>,
mingo@kernel.org, LKML <linux-kernel@vger.kernel.org>,
roland@kernel.org, Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] sched: balance_cpu to consider other cpus in its group as target of (pinned) task migration
Date: Mon, 04 Jun 2012 14:47:43 +0200 [thread overview]
Message-ID: <1338814063.7356.192.camel@marge.simpson.net> (raw)
In-Reply-To: <1338810796.28282.32.camel@twins>
On Mon, 2012-06-04 at 13:53 +0200, Peter Zijlstra wrote:
> On Mon, 2012-06-04 at 11:25 +0200, Mike Galbraith wrote:
> > Isn't this poking the wrong spot?
>
> Yes and no, the use-case is definitely so-so.. However, even if a FIFO
> task were to only consume 95% of time, we might still want to balance
> things differently, and I don't think we do the sane thing there either.
You need a good reason to run RT, and being able to starve others to
death ain't it, so I don't see a good reason to care about the 95% case
enough to fiddle with load balancing to accommodate the oddball case.
Agreed it is a hole, but it's one dug by root. If you need so much CPU
that you can and will starve SCHED_OTHER to death, you need isolation
from SCHED_OTHER, lest they do evil things to your deadline, just as
much as they desperately need protection from your evil CPU usage ;-)
-Mike
next prev parent reply other threads:[~2012-06-04 12:47 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-04 5:57 [PATCH] sched: balance_cpu to consider other cpus in its group as target of (pinned) task migration Prashanth Nageshappa
2012-06-04 9:00 ` Peter Zijlstra
2012-06-04 11:41 ` Srivatsa Vaddagiri
2012-06-04 11:49 ` Peter Zijlstra
2012-06-04 12:27 ` Srivatsa Vaddagiri
2012-06-04 11:51 ` Peter Zijlstra
2012-06-04 9:25 ` Mike Galbraith
2012-06-04 11:53 ` Peter Zijlstra
2012-06-04 12:47 ` Mike Galbraith [this message]
2012-06-04 13:07 ` Srivatsa Vaddagiri
2012-06-04 14:30 ` Mike Galbraith
2012-06-04 14:38 ` Srivatsa Vaddagiri
2012-06-04 14:41 ` Mike Galbraith
2012-06-04 15:00 ` Srivatsa Vaddagiri
2012-06-04 15:21 ` Peter Zijlstra
2012-06-04 15:25 ` Srivatsa Vaddagiri
2012-06-04 15:33 ` Peter Zijlstra
2012-06-04 15:46 ` Srivatsa Vaddagiri
2012-06-04 16:56 ` Mike Galbraith
2012-06-04 17:37 ` Srivatsa Vaddagiri
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