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* [PATCH v5 0/4] crc32c: Add faster algorithm and self-test code
@ 2011-10-04 23:53 Darrick J. Wong
  2011-10-04 23:54 ` [PATCH 1/4] crc32: Bolt on crc32c Darrick J. Wong
                   ` (4 more replies)
  0 siblings, 5 replies; 15+ messages in thread
From: Darrick J. Wong @ 2011-10-04 23:53 UTC (permalink / raw)
  To: Andreas Dilger, Herbert Xu, Theodore Tso, David Miller,
	Darrick J. Wong
  Cc: Joakim Tjernlund, Bob Pearson, linux-kernel, Mingming Cao,
	linux-crypto, linux-fsdevel, linux-ext4

Hi all,

This patchset (re)uses Bob Pearson's crc32 slice-by-8 code to stamp out a
software crc32c implementation.  It requires that all ten of his patches (at
least the ones dated 31 Aug 2011) be applied.  It removes the crc32c
implementation in crypto/ in favor of using the stamped-out one in lib/.  There
is also a change to Kconfig so that the kernel builder can pick an
implementation best suited for the hardware.

The motivation for this patchset is that I am working on adding full metadata
checksumming to ext4.  As far as performance impact of adding checksumming
goes, I see nearly no change with a standard mail server ffsb simulation.  On a
test that involves only file creation and deletion and extent tree writes, I
see a drop of about 50 pcercent with the current kernel crc32c implementation;
this improves to a drop of about 20 percent with the enclosed crc32c code.

When metadata is usually a small fraction of total IO, this new implementation
doesn't help much because metadata is usually a small fraction of total IO.
However, when we are doing IO that is almost all metadata (such as rm -rf'ing a
tree), then this patch speeds up the operation substantially.

Incidentally, given that iscsi, sctp, and btrfs also use crc32c, this patchset
should improve their speed as well.  I have not yet quantified that, however.

--D

^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2011-11-15 15:38 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-10-04 23:53 [PATCH v5 0/4] crc32c: Add faster algorithm and self-test code Darrick J. Wong
2011-10-04 23:54 ` [PATCH 1/4] crc32: Bolt on crc32c Darrick J. Wong
2011-10-21 12:28   ` Herbert Xu
2011-10-21 16:57     ` Darrick J. Wong
2011-10-21 19:15       ` Herbert Xu
2011-10-26 17:16         ` Darrick J. Wong
2011-10-27 18:32           ` Time for a fresh slice-by-8 crc32.c posting? Darrick J. Wong
2011-11-15  8:48         ` [PATCH 1/4] crc32: Bolt on crc32c Darrick J. Wong
2011-11-15 15:38           ` Bob Pearson
2011-10-04 23:54 ` [PATCH 2/4] crypto: crc32c should use library implementation Darrick J. Wong
2011-10-04 23:54 ` [PATCH 3/4] crc32: Add self-test code for crc32c Darrick J. Wong
2011-10-04 23:54 ` [PATCH 4/4] crc32: Select an algorithm via kconfig Darrick J. Wong
2011-10-08  7:42   ` [PATCH v5.1 " Darrick J. Wong
2011-10-06 20:20 ` [PATCH v5 0/4] crc32c: Add faster algorithm and self-test code Darrick J. Wong
2011-10-07  7:38   ` Joakim Tjernlund

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