Date: Sun, 20 Sep 2009 20:30:48 +0200
From: Arjan van de Ven <arjan@infradead.org>
To: Robert Hancock <hancockrwd@gmail.com>
Cc: Junhee Lee <junhee@netsys.kaist.ac.kr>, linux-kernel@vger.kernel.org
Subject: Re: microsecond event scheduling in an application
Message-ID: <20090920203048.7b1b5aa2@infradead.org>
In-Reply-To: <4AB673C1.7020909@gmail.com>
References: <015f01ca3090$85e8a280$91b9e780$@kaist.ac.kr>
	<4AB673C1.7020909@gmail.com>
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On Sun, 20 Sep 2009 12:26:09 -0600
Robert Hancock <hancockrwd@gmail.com> wrote:

> On 09/08/2009 08:27 AM, Junhee Lee wrote:
> > I am working on event scheduler which handles events in microsecond
> > level. Actual this program is a network emulator using simulation
> > codes. I'd like to expect that network emulator is working as
> > simulation behaviors. Thus high resolution timer interrupt is
> > required. But high resolution timer interrupt derived by high tick
> > frequency (jiffies clock) must effect the system performance.
> > Are there any comments or ways to support microsecond event
> > scheduling without performance degradation?
> 
> Just increasing HZ will degrade performance, yes, but we have
> hrtimers now which should be able to use granularities smaller than
> one jiffy, so it shouldn't be needed..


select/poll use hrtimers, which are jiffies independent....

you'll be hard pressed to notice jiffies granularity in userspace
nowadays..


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
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