Date: Fri, 19 Mar 2004 15:06:05 +0100
Message-ID: <s5hoeqtaq42.wl@alsa2.suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: Chris Mason <mason@suse.com>
Cc: Andrew Morton <akpm@osdl.org>, andrea@suse.de, mjy@geizhals.at,
       linux-kernel@vger.kernel.org
Subject: Re: CONFIG_PREEMPT and server workloads
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At Fri, 19 Mar 2004 08:46:47 -0500,
Chris Mason wrote:
> 
> > - in write_ordered_buffers().
> > 
> >   i still don't figure out where.  we have already cond_resched()
> >   check in the loops.  this one is triggered when i write bulk data
> >   in parallel (1GB write with 20 threads at the same time), resulting
> >   in up to 2ms.
> > 
> Hmmm, is this a lock latency or just noticing that write() takes a long
> time?
> 
> It's probably this:
> 	if (chunk.nr == 0 && need_resched) {
> 
> I'll bet the latencies go away when you drop the chunk.nr test.

i'll give a try.  thanks for hints.


Takashi
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