Date: Sun, 20 Sep 2009 09:40:22 +0200
From: Arjan van de Ven <arjan@infradead.org>
To: Tim Blechmann <tim@klingt.org>
Cc: linux-kernel@vger.kernel.org, Daniel J Blueman <daniel.blueman@gmail.com>
Subject: Re: tickless and HZ=1000 throughput advantage?
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On Sun, 20 Sep 2009 09:34:30 +0200
Tim Blechmann <tim@klingt.org> wrote:

> On 09/20/2009 01:12 AM, Ben Nizette wrote:
> > On Sat, 2009-09-19 at 18:50 +0100, Daniel J Blueman wrote:
> > 
> >> Agreed. Do you think there is still a small case for moving to
> >> HZ=1000 (given it's effectively free) in situations like:
> > 
> > Sure HZ=1000 gives you more accurate sleeps, that's kind of the
> > point, but since when has it been "effectively free"?
> > http://lwn.net/Articles/331607/
> 
> i'd be curious, what effect does it have on userspace applications?
> like, does it effect the wakeup latency of userspace (pthread)
> mutexes/conditions or posix semaphores?

the impact to userspace should be zero nowadays since select/poll/etc
moved to hrtimers, which are HZ-independent.


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
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