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Subject: Re: [patch] voluntary-preempt-2.6.8.1-P4
From: Lee Revell <rlrevell@joe-job.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
       Thomas Charbonnel <thomas@undata.org>,
       Florian Schmidt <mista.tapas@gmx.net>,
       Felipe Alfaro Solana <felipe_alfaro@linuxmail.org>
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On Fri, 2004-08-20 at 04:13, Ingo Molnar wrote:
> * Lee Revell <rlrevell@joe-job.com> wrote:
> 
> > >   http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.8.1-P4
> > 
> > I think I am seeing those weird ~1 ms latencies still (actually I am not
> > sure I saw before now):
> > 
> > http://krustophenia.net/testresults.php?dataset=2.6.8.1-P4#/var/www/2.6.8.1-P4/kswapd_latency_trace.txt
> 
> this is a 9 msec latency in fact. I know what's going on - it's the
> get_swap_page() locking - i looked at it once already but there's no
> immediate silver arrow. As we allocate more and more swap entries the
> longer the scan gets.
> 

This is an extreme load situation, so I don't think it will be a
real-world problem.  I have not seen it under any normal workload.

What about this one:

http://krustophenia.net/testresults.php?dataset=2.6.8.1-P4#/var/www/2.6.8.1-P4/netif_receive_skb_latency_trace.txt

This appears during normal use.

Lee