Date: Wed, 30 Jan 2008 11:19:28 -0800 (PST)
From: Christoph Lameter <clameter@sgi.com>
To: Jack Steiner <steiner@sgi.com>
cc: Andrea Arcangeli <andrea@qumranet.com>, Robin Holt <holt@sgi.com>,
       Avi Kivity <avi@qumranet.com>, Izik Eidus <izike@qumranet.com>,
       Nick Piggin <npiggin@suse.de>, kvm-devel@lists.sourceforge.net,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org, daniel.blueman@quadrics.com,
       Hugh Dickins <hugh@veritas.com>
Subject: Re: [patch 1/6] mmu_notifier: Core code
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References: <20080130022909.677301714@sgi.com> <20080130022944.236370194@sgi.com>
 <20080130153749.GN7233@v2.random> <20080130155306.GA13746@sgi.com>
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On Wed, 30 Jan 2008, Jack Steiner wrote:

> Moving to a different lock solves the problem.

Well it gets us back to the issue why we removed the lock. As Robin said 
before: If its global then we can have a huge number of tasks contending 
for the lock on startup of a process with a large number of ranks. The 
reason to go to mmap_sem was that it was placed in the mm_struct and so we 
would just have a couple of contentions per mm_struct.

I'll be looking for some other way to do this.

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