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To: djwong@us.ibm.com
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
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Subject: Re: [PATCH v1 00/16] ext4: Add metadata checksumming
From: "Martin K. Petersen" <martin.petersen@oracle.com>
Organization: Oracle
References: <20110901003030.31048.99467.stgit@elm3c44.beaverton.ibm.com>
	<CAGpXXZ+Cq9_aS4BPC5BKNj6aWHzzL7+e8ZQKO3=C7UV+xcnqWA@mail.gmail.com>
	<20110902182214.GC12086@tux1.beaverton.ibm.com>
	<yq1d3fgwn5c.fsf@sermon.lab.mkp.net>
	<20110905184524.GQ12086@tux1.beaverton.ibm.com>
Date: Tue, 06 Sep 2011 08:59:53 -0400
In-Reply-To: <20110905184524.GQ12086@tux1.beaverton.ibm.com> (Darrick
	J. Wong's message of "Mon, 5 Sep 2011 11:45:24 -0700")
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>>>>> "Darrick" == Darrick J Wong <djwong@us.ibm.com> writes:

Darrick> I have some benchmarking data for various crc algorithms here:
Darrick> https://ext4.wiki.kernel.org/index.php/Ext4_Metadata_Checksums#Benchmarking

I've been meaning to update my own benchmark results from a few years
ago but your table is much more comprehensive. Nice work!


Darrick> Yes, the only downside to the slice-by-8 method is that it eats
Darrick> 8K of data cache for the table.  Not a huge issue on recent
Darrick> Intel and POWER where the L1D is 32K, but I imagine it could be
Darrick> painful elsewhere.

I'll see if I can come up with something better for the DIF CRC. It's
always calculated over either 512 or 4096-byte buffers.

-- 
Martin K. Petersen	Oracle Linux Engineering