From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Arjan van de Ven <arjan@infradead.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] hrtimers: Special-case zero length sleeps
Date: Wed, 15 Feb 2012 20:22:21 +0000 [thread overview]
Message-ID: <20120215202221.GA29552@srcf.ucam.org> (raw)
In-Reply-To: <alpine.LFD.2.02.1202152059230.2794@ionos>
On Wed, Feb 15, 2012 at 09:14:30PM +0100, Thomas Gleixner wrote:
> Just for the extended fun of it: The pre hrtimer implementation in
> Linux put the task on sleep as well up to the next jiffies boundary,
> so anything which used sleep(0) on a pre hrtimer kernel was going to
> sleep. That's also the case today when high resolution timers are
> disabled (compile or runtime).
>
> So anything which relies on sleep(0) as a fast scheduling point is and
> has been broken forever.
Excellent. So the real question is what /should/ sleep(0) do - nothing,
schedule or sleep for an arbitrary period of time that could be years?
--
Matthew Garrett | mjg59@srcf.ucam.org
next prev parent reply other threads:[~2012-02-15 20:22 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-29 14:59 [PATCH] hrtimers: Special-case zero length sleeps Matthew Garrett
2012-02-15 14:40 ` Thomas Gleixner
2012-02-15 14:52 ` Matthew Garrett
2012-02-15 20:14 ` Thomas Gleixner
2012-02-15 20:22 ` Matthew Garrett [this message]
2012-02-15 20:30 ` Thomas Gleixner
2012-02-15 20:38 ` Matthew Garrett
2012-02-15 20:40 ` Peter Zijlstra
2012-02-15 20:43 ` Matthew Garrett
2012-02-15 20:46 ` Thomas Gleixner
2012-02-15 20:47 ` Matthew Garrett
2012-02-16 14:27 ` Matthew Garrett
2012-02-16 14:31 ` Alan Cox
2012-02-16 14:51 ` Peter Zijlstra
2012-02-16 15:01 ` Matthew Garrett
2012-02-16 19:09 ` Thomas Gleixner
2012-02-15 14:54 ` Peter Zijlstra
2012-02-15 14:58 ` Matthew Garrett
2012-02-15 20:22 ` Thomas Gleixner
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