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From: Ingo Molnar <mingo@kernel.org>
To: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	NeilBrown <neilb@suse.de>, Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	lkml <linux-kernel@vger.kernel.org>,
	"Dr. H. Nikolaus Schaller" <hns@goldelico.com>,
	Marek Belisko <marek@goldelico.com>,
	Mark Brown <broonie@opensource.wolfsonmicro.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH/RFC] wait_for_completion_timeout() considered harmful.
Date: Tue, 19 Nov 2013 08:05:57 +0100	[thread overview]
Message-ID: <20131119070557.GD32367@gmail.com> (raw)
In-Reply-To: <20131118174902.312d8fa6@lwn.net>


* Jonathan Corbet <corbet@lwn.net> wrote:

> On Tue, 19 Nov 2013 00:42:09 +0100
> Peter Zijlstra <peterz@infradead.org> wrote:
> 
> > I briefly talked to Thomas about this earlier today and we need to 
> > fix this at a lower level -- the quick 'n dirty solution is to add 
> > 1 jiffy down in the timer-wheel when we enqueue these things.
> 
> That can lead to situations like the one I encountered years ago 
> where msleep(1) would snooze for 20ms.  I didn't get much love for 
> my idea of switching msleep() to hrtimers back then, but I still 
> think it might be be better to provide the resolution that the 
> interface appears to promise.

That looks like a sensible approach - mind resending that patch? We 
can put it into the timer tree and see what happens.

Thanks,

	Ingo

  reply	other threads:[~2013-11-19  7:06 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-16 21:06 [PATCH/RFC] wait_for_completion_timeout() considered harmful NeilBrown
2013-11-18 23:27 ` Andrew Morton
2013-11-18 23:42   ` Peter Zijlstra
2013-11-19  0:49     ` Jonathan Corbet
2013-11-19  7:05       ` Ingo Molnar [this message]
2013-11-19  8:29       ` Peter Zijlstra
2013-11-18 23:44   ` NeilBrown
2013-11-19  8:25     ` Peter Zijlstra
2013-11-19  8:58       ` NeilBrown
2013-11-19 12:23         ` Peter Zijlstra
2013-11-19 14:39           ` Thomas Gleixner

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