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Date: Tue, 19 Nov 2013 08:05:57 +0100
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.
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* 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