From: David Ahern <dsahern@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: deadlock in scheduler enabling HRTICK feature
Date: Wed, 26 Jun 2013 10:46:33 -0600 [thread overview]
Message-ID: <51CB1AE9.5090709@gmail.com> (raw)
In-Reply-To: <20130626070533.GA3601@dyad.programming.kicks-ass.net>
On 6/26/13 1:05 AM, Peter Zijlstra wrote:
>> What is the expectation that the feature provides? not a whole lot of
>> documentation on it. I walked down the path wondering if it solved an odd
>> problem we are seeing with the CFS in 2.6.27 kernel.
>
> Its supposed to use hrtimers for slice expiry instead of the regular tick.
So theoretically CPU bound tasks would get preempted sooner? That was my
guess/hope anyways.
>
> IIRC it did work at some point but bitrotted a bit since. The good news is that
> the deadline scheduler wants to use it and I'll probably have to fix it up
> then.
Hmmm.... meaning I should not be expecting anything in the next couple
of months? Any gut opinions on how to approach the nested problem - at
least a quick hack for me to see if this option has any impact on our
problem? eg., a CPU variable noting we already have the runqueue lock
and no need to grab it a second time.
David
next prev parent reply other threads:[~2013-06-26 16:46 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-25 21:05 deadlock in scheduler enabling HRTICK feature David Ahern
2013-06-25 21:17 ` Peter Zijlstra
2013-06-25 21:20 ` David Ahern
2013-06-26 7:05 ` Peter Zijlstra
2013-06-26 16:46 ` David Ahern [this message]
2013-06-27 10:43 ` Peter Zijlstra
2013-06-27 10:53 ` Peter Zijlstra
2013-06-27 12:28 ` Mike Galbraith
2013-06-27 13:06 ` Ingo Molnar
2013-06-27 19:18 ` Andy Lutomirski
2013-06-27 20:37 ` Peter Zijlstra
2013-06-27 22:28 ` David Ahern
2013-06-28 9:00 ` Ingo Molnar
2013-06-28 9:18 ` Peter Zijlstra
2013-07-12 13:29 ` [tip:sched/core] sched: Fix HRTICK tip-bot for Peter Zijlstra
2013-06-28 9:09 ` deadlock in scheduler enabling HRTICK feature Peter Zijlstra
2013-06-28 17:28 ` David Ahern
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