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Subject: Re: [patch] voluntary-preempt-2.6.8.1-P1
From: Lee Revell <rlrevell@joe-job.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Florian Schmidt <mista.tapas@gmx.net>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       Felipe Alfaro Solana <felipe_alfaro@linuxmail.org>
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On Tue, 2004-08-17 at 04:18, Ingo Molnar wrote:
> * Ingo Molnar <mingo@elte.hu> wrote:
> 
> > > Yes, Ingo identified an issue with copy_page_range, I don't think it's
> > > fixed yet.  See the voluntary-preempt-2.6.8.1-P0 thread.
> > 
> > right, it's not fixed yet. It's not a trivial critical section - we
> > are holding two locks and are mapping two atomic kmaps.
> 
> fortunately it's easier than i thought - neither the source pmd nor the
> target pmd can go away so we can simply drop the locks, reschedule, and
> remap. Does the patch below (ontop of -P3) fix the copy_page_range()
> latencies you are seeing?
> 

Yes, this fixes it.  Now the most frequent issue is the xfree86
unmap_vmas latency:

http://krustophenia.net/testresults.php?dataset=2.6.8.1-P3

Lee