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Date: Mon, 5 Sep 2011 20:27:27 +0200
From: Andi Kleen <andi@firstfloor.org>
To: "Darrick J. Wong" <djwong@us.ibm.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>, Theodore Tso <tytso@mit.edu>,
        Sunil Mushran <sunil.mushran@oracle.com>,
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        Andi Kleen <andi@firstfloor.org>, Mingming Cao <cmm@us.ibm.com>,
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        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-ext4@vger.kernel.org, Coly Li <colyli@gmail.com>
Subject: Re: [PATCH 08/16] ext4: Calculate and verify checksums for inode bitmaps
Message-ID: <20110905182727.GH7761@one.firstfloor.org>
References: <20110901003030.31048.99467.stgit@elm3c44.beaverton.ibm.com> <20110901003127.31048.13983.stgit@elm3c44.beaverton.ibm.com> <2A834E5A-F07E-4B1E-835B-FBEE3FD7A103@dilger.ca> <20110902191828.GL12086@tux1.beaverton.ibm.com> <8D646179-FD76-4362-A051-8C6ADB3CE1B3@dilger.ca> <20110905182250.GO12086@tux1.beaverton.ibm.com>
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One very interesting optimization would be to profile the metadata workload
where you got the slowdown and try to figure out which fields
were most commonly updated.

If it's some superblock fields or similar maybe those could get their separate
crcs that could be separatedly computed at much lower cost.

-Andi