linux-kernel - Re: [RFC][PATCH] sched: might_sleep(): do rate-limiting before sanity checks

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Message-ID: <20150625074333.GU3644@twins.programming.kicks-ass.net>
Date:	Thu, 25 Jun 2015 09:43:33 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Dave Hansen <dave@...1.net>
Cc:	mingo@...hat.com, linux-kernel@...r.kernel.org,
	dave.hansen@...ux.intel.com, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RFC][PATCH] sched: might_sleep(): do rate-limiting before
 sanity checks

On Wed, Jun 24, 2015 at 08:36:38PM -0700, Dave Hansen wrote:
> On 06/24/2015 05:03 PM, Dave Hansen wrote:
> > In any case, we ratelimit might_sleep() checks anyway.  But, we
> > do the ratelimiting *after* we check the other conditions for
> > might_sleep() including the (costly) irqs_disabled() call.
> 
> Thinking about this a bit more, this patch is wrong.
> 
> This only does a _check_ once per jiffy instead of just one warning per
> jiffy, which is totally bogus.
> 
> I would be interested, though, if anybody has any ideas about speeding
> up the irqs_disabled() checking.

Thomas has something up his sleeve..
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