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Date: Thu, 21 Apr 2011 14:07:38 +0800
From: Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [PATCH 0/6] writeback: moving expire targets for
 background/kupdate works
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 <20110421055031.GA23711@localhost>
 <20110421055634.GA26187@infradead.org>
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To: Christoph Hellwig <hch@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.cz>, Mel Gorman <mel@linux.vnet.ibm.com>, Dave Chinner <david@fromorbit.com>, Trond Myklebust <Trond.Myklebust@netapp.com>, Itaru Kitayama <kitayama@cl.bb4u.ne.jp>, Minchan Kim <minchan.kim@gmail.com>, LKML <linux-kernel@vger.kernel.org>, "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>, Linux Memory Management List <linux-mm@kvack.org>

On Thu, Apr 21, 2011 at 01:56:34PM +0800, Christoph Hellwig wrote:
> On Thu, Apr 21, 2011 at 01:50:31PM +0800, Wu Fengguang wrote:
> > Hi Christoph,
> > 
> > On Thu, Apr 21, 2011 at 12:34:50PM +0800, Christoph Hellwig wrote:
> > > Hi Wu,
> > > 
> > > if you're queueing up writeback changes can you look into splitting
> > > inode_wb_list_lock as it was done in earlier versions of the inode
> > > scalability patches?  Especially if we don't get the I/O less
> > > balance_dirty_pages in ASAP it'll at least allows us to scale the
> > > busy waiting for the list manipulationes to one CPU per BDI.
> > 
> > Do you mean to split inode_wb_list_lock into struct bdi_writeback? 
> > So as to improve at least the JBOD case now and hopefully benefit the
> > 1-bdi case when switching to multiple bdi_writeback per bdi in future?
> > 
> > I've not touched any locking code before, but it looks like some dumb
> > code replacement. Let me try it :)
> 
> I can do the patch if you want, it would be useful to carry it in your
> series to avoid conflicts, though.

I see. I'll do it, thanks!

Thanks,
Fengguang

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