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Subject: Re: [patch 1/7] cpusets: add dirty map to struct address_space
From: Peter Zijlstra <peterz@infradead.org>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Christoph Lameter <cl@linux-foundation.org>,
       Nick Piggin <npiggin@suse.de>, Paul Menage <menage@google.com>,
       Derek Fults <dfults@sgi.com>, linux-kernel@vger.kernel.org
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Date: Thu, 30 Oct 2008 09:38:17 +0100
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On Tue, 2008-10-28 at 18:13 -0700, David Rientjes wrote:
> On Tue, 28 Oct 2008, David Rientjes wrote:
> 
> > Yeah, if we don't serialize with tree_lock then we'll need to protect the 
> > attachment of mapping->dirty_nodes with a new spinlock in struct 
> > address_space (and only for configs where MAX_NUMNODES > BITS_PER_LONG). 
> > That locking overhead is negligible when mapping->dirty_nodes is non-NULL 
> > since there's no requirement to protect the setting of the node in the 
> > nodemask.
> > 
> > Are your concurrent pagecache patches in the latest mmotm?  If so, I can 
> > rebase this entire patchset off that.
> 
> We're still taking mapping->tree_lock in both __set_page_dirty() and 
> __set_page_dirty_nobuffers() in today's mmotm.
> 
> When tree_lock is removed with your patchset, we can add a spinlock to 
> protect mapping->dirty_nodes when MAX_NUMNODES > BITS_PER_LONG.
> 
> Would you like to fold this patch into your series (which assumes we're 
> not taking mapping->tree_lock in either of the two callers above)?

Thanks!, I was working on cleaning up the patches to submit again
soonish.