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* [PATCH v2 0/3] crc32c: Add faster algorithm and self-test code
@ 2011-09-27 22:12 ` Darrick J. Wong
  0 siblings, 0 replies; 18+ messages in thread
From: Darrick J. Wong @ 2011-09-27 22:12 UTC (permalink / raw)
  To: Andreas Dilger, Herbert Xu, Theodore Tso, David Miller, Darrick J. Wong
  Cc: Bob Pearson, linux-kernel, Mingming Cao, linux-crypto,
	linux-fsdevel, linux-ext4

Hi all,

This patchset replaces the current crc32c software implementation, which uses a
slow per-byte lookup table algorithm, with a faster implementation that uses an
adaptation of the slice-by-8 algorithm that Bob Pearson has been pushing for
crc32.

The motivation for this patchset is that I am working on adding full metadata
checksumming to ext4[1].  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.

Please have a look at the patches, and please feel free to suggest any changes.
I will be at LPC next week if anyone wishes to discuss, debate, or protest.

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.

v2: Use the crypto test manager code to check crc32c operation.

--D

[1] https://ext4.wiki.kernel.org/index.php/Ext4_Metadata_Checksums

^ permalink raw reply	[flat|nested] 18+ messages in thread
* [PATCH v1 0/3] crc32c: Add faster algorithm and self-test code
@ 2011-09-01  0:33 Darrick J. Wong
  2011-09-01  0:33   ` Darrick J. Wong
  0 siblings, 1 reply; 18+ messages in thread
From: Darrick J. Wong @ 2011-09-01  0:33 UTC (permalink / raw)
  To: Andreas Dilger, Herbert Xu, Theodore Tso, David Miller, Darrick J. Wong
  Cc: Bob Pearson, linux-kernel, Mingming Cao, linux-crypto,
	linux-fsdevel, linux-ext4

Hi all,

This patchset replaces the current crc32c software implementation, which uses a
slow per-byte lookup table algorithm, with a faster implementation that uses an
adaptation of the slice-by-8 algorithm that Bob Pearson has been pushing for
crc32.

The motivation for this patchset is that I am working on adding full metadata
checksumming to ext4[1].  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.

Please have a look at the patches, and please feel free to suggest any changes.
I will be at LPC next week if anyone wishes to discuss, debate, or protest.

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

[1] https://ext4.wiki.kernel.org/index.php/Ext4_Metadata_Checksums

^ permalink raw reply	[flat|nested] 18+ messages in thread

end of thread, other threads:[~2011-09-29  0:02 UTC | newest]

Thread overview: 18+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-09-27 22:12 [PATCH v2 0/3] crc32c: Add faster algorithm and self-test code Darrick J. Wong
2011-09-27 22:12 ` Darrick J. Wong
2011-09-27 22:12 ` [PATCH 1/3] crc32c: Implement CRC32c with slicing-by-8 algorithm Darrick J. Wong
2011-09-27 22:12   ` Darrick J. Wong
2011-09-27 22:12 ` [PATCH 2/3] libcrc32c: Expose big-endian version of crc32c Darrick J. Wong
2011-09-27 22:12   ` Darrick J. Wong
2011-09-28  3:53   ` Herbert Xu
2011-09-28  3:53     ` Herbert Xu
2011-09-28 16:51     ` Darrick J. Wong
2011-09-28 16:51       ` Darrick J. Wong
2011-09-29  0:02       ` Darrick J. Wong
2011-09-29  0:02         ` Darrick J. Wong
2011-09-27 22:13 ` [PATCH 3/3] crc32c: Implement a self-test for CRC32c Darrick J. Wong
2011-09-27 22:13   ` Darrick J. Wong
2011-09-27 23:07 ` [PATCH v2 0/3] crc32c: Add faster algorithm and self-test code Darrick J. Wong
2011-09-27 23:07   ` Darrick J. Wong
  -- strict thread matches above, loose matches on Subject: below --
2011-09-01  0:33 [PATCH v1 " Darrick J. Wong
2011-09-01  0:33 ` [PATCH 2/3] libcrc32c: Expose big-endian version of crc32c Darrick J. Wong
2011-09-01  0:33   ` Darrick J. Wong

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