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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

  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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