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Date: Wed, 7 Oct 2009 10:26:32 -0400
From: Theodore Tso <tytso@mit.edu>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Christoph Hellwig <hch@infradead.org>,
       Dave Chinner <david@fromorbit.com>,
       Chris Mason <chris.mason@oracle.com>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Li Shaohua <shaohua.li@intel.com>,
       Myklebust Trond <Trond.Myklebust@netapp.com>,
       "jens.axboe@oracle.com" <jens.axboe@oracle.com>,
       Jan Kara <jack@suse.cz>, Nick Piggin <npiggin@suse.de>,
       linux-fsdevel@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 00/45] some writeback experiments
Message-ID: <20091007142632.GM17883@mit.edu>
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	Wu Fengguang <fengguang.wu@intel.com>,
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	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Li Shaohua <shaohua.li@intel.com>,
	Myklebust Trond <Trond.Myklebust@netapp.com>,
	"jens.axboe@oracle.com" <jens.axboe@oracle.com>,
	Jan Kara <jack@suse.cz>, Nick Piggin <npiggin@suse.de>,
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On Wed, Oct 07, 2009 at 03:38:18PM +0800, Wu Fengguang wrote:
> 
> The estimated writeback bandwidth is about 1/2 the real throughput
> for ext2/3/4 and btrfs; noticeable bigger than real throughput for NFS; and
> cannot be estimated at all for XFS.  Very interesting..

Can you expand on what you mean here?  Estimated write bandwidth of
what?  And what are you comparing it against?

I'm having trouble understanding your note (which I'm guessing you
write fairly late at night?  :-)

Thanks,

						- Ted