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Subject: Re: 2.6.16-rc1: 28ms latency when process with lots of swapped
	memory exits
From: Lee Revell <rlrevell@joe-job.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Hugh Dickins <hugh@veritas.com>,
       linux-kernel <linux-kernel@vger.kernel.org>
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Date: Tue, 14 Mar 2006 17:38:58 -0500
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On Tue, 2006-03-14 at 22:01 +0100, Ingo Molnar wrote:
> hm, where does the latency come from? We do have a lockbreaker in 
> unmap_vmas():
> 
>                         if (need_resched() ||
>                                 (i_mmap_lock &&
> need_lockbreak(i_mmap_lock))) {
>                                 if (i_mmap_lock) {
>                                         *tlbp = NULL;
>                                         goto out;
>                                 }
>                                 cond_resched();
>                         }
> 
> 
> why doesnt this break up the 28ms latency?
> 

But the preempt count is >= 2, doesn't that mean some other lock must be
held also, or someone called preempt_disable?

Lee