From: "Andi Kleen" <andi@firstfloor.org>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: "Andi Kleen" <andi@firstfloor.org>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
djwong@us.ibm.com, "Greg Freemyer" <greg.freemyer@gmail.com>,
"Andreas Dilger" <adilger.kernel@dilger.ca>,
"Theodore Tso" <tytso@mit.edu>,
"Sunil Mushran" <sunil.mushran@oracle.com>,
"Amir Goldstein" <amir73il@gmail.com>,
"linux-kernel" <linux-kernel@vger.kernel.org>,
"Mingming Cao" <cmm@us.ibm.com>,
"Joel Becker" <jlbec@evilplan.org>,
"linux-fsdevel" <linux-fsdevel@vger.kernel.org>,
linux-ext4@vger.kernel.org, "Coly Li" <colyli@gmail.com>
Subject: Re: [PATCH v1 00/16] ext4: Add metadata checksumming
Date: Sun, 4 Sep 2011 19:44:55 +0200 [thread overview]
Message-ID: <88f8907569619968aa7b4a8c669d5aba.squirrel@www.firstfloor.org> (raw)
In-Reply-To: <yq14o0scjmg.fsf@sermon.lab.mkp.net>
>>>>>> "Andi" == Andi Kleen <andi@firstfloor.org> writes:
>
>>> On Westmere and beyond it is possible to accelerate generic CRC
>>> calculation using the PCLMULQDQ operation. There are many of our CRC
>
> Andi> Faster than the lookup table? That's hard to believe.
>
> Using PCLMULQDQ you can parallelize the calculation. You can even boost
> hw CRC32C performance that way.
>
> http://download.intel.com/design/intarch/papers/323405.pdf
>
> http://download.intel.com/design/intarch/papers/323102.pdf
Doesn't have any performance numbers.
You need to keep in mind that PCLMULQDQ uses FPU state, so any
speedup for the kernel must be large enough to amortize the cost of
saving the FPU state.
Typically that only works out for quite large buffers, but
kernel buffers are relatively small.
For the ext4 metadata a better approach is probably some sort of
incremental CRC, or possibly separate CRCs for very commonly
changed fields. When I looked at this most changes were only for
small fields.
-Andi
next prev parent reply other threads:[~2011-09-04 17:44 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-01 0:30 [PATCH v1 00/16] ext4: Add metadata checksumming Darrick J. Wong
2011-09-01 0:30 ` [PATCH 01/16] ext4: ext4_dx_add_entry should dirty directory metadata with the directory inode Darrick J. Wong
2011-09-01 0:30 ` [PATCH 02/16] ext4: ext4_rename should dirty dir_bh with the correct directory Darrick J. Wong
2011-09-01 0:30 ` [PATCH 03/16] ext4: ext4_mkdir should dirty dir_block with the parent inode Darrick J. Wong
2011-09-01 0:30 ` [PATCH 04/16] ext4: Create a new BH_Verified flag to avoid unnecessary metadata validation Darrick J. Wong
2011-09-01 0:31 ` [PATCH 05/16] ext4: Create a rocompat flag for extended metadata checksumming Darrick J. Wong
2011-09-01 0:31 ` [PATCH 06/16] ext4: Calculate and verify inode checksums Darrick J. Wong
2011-09-01 2:30 ` Andreas Dilger
2011-09-02 19:32 ` Darrick J. Wong
2011-09-02 22:02 ` Andreas Dilger
2011-09-05 17:57 ` Darrick J. Wong
2011-09-01 0:31 ` [PATCH 07/16] ext4: Create bitmap checksum helper functions Darrick J. Wong
2011-09-01 0:31 ` [PATCH 08/16] ext4: Calculate and verify checksums for inode bitmaps Darrick J. Wong
2011-09-01 4:49 ` Andreas Dilger
2011-09-02 19:18 ` Darrick J. Wong
2011-09-02 21:27 ` Andreas Dilger
2011-09-05 18:22 ` Darrick J. Wong
2011-09-05 18:27 ` Andi Kleen
2011-09-05 19:45 ` James Bottomley
2011-09-05 22:12 ` Darrick J. Wong
2011-09-01 0:31 ` [PATCH 09/16] ext4: Calculate and verify block bitmap checksum Darrick J. Wong
[not found] ` <2492E720-3316-4561-8C9C-BBC6E8670EAD@dilger.ca>
2011-09-02 19:08 ` Darrick J. Wong
2011-09-02 21:06 ` Andreas Dilger
2011-09-01 0:31 ` [PATCH 10/16] ext4: Verify and calculate checksums for extent tree blocks Darrick J. Wong
[not found] ` <26584BE9-B716-40D5-B3B4-8C5912869648@dilger.ca>
2011-09-02 19:02 ` Darrick J. Wong
2011-09-01 0:31 ` [PATCH 11/16] ext4: Calculate and verify checksums for htree nodes Darrick J. Wong
2011-09-01 0:31 ` [PATCH 12/16] ext4: Calculate and verify checksums of directory leaf blocks Darrick J. Wong
[not found] ` <4D5D8FB2-0D8A-4D30-B6D8-51158395C1C9@dilger.ca>
2011-09-02 18:57 ` Darrick J. Wong
2011-09-02 20:52 ` Andreas Dilger
2011-09-05 18:30 ` Darrick J. Wong
2011-09-01 0:32 ` [PATCH 13/16] ext4: Calculate and verify checksums of extended attribute blocks Darrick J. Wong
[not found] ` <F4A42DCE-F91C-419B-9153-65A7EA91D241@dilger.ca>
2011-09-02 18:43 ` Darrick J. Wong
2011-09-01 0:32 ` [PATCH 14/16] ext4: Make inode checksum cover empty space Darrick J. Wong
[not found] ` <4540D5DB-53D9-4C33-BC6B-868870D42AF3@dilger.ca>
2011-09-02 18:42 ` Darrick J. Wong
2011-09-01 0:32 ` [PATCH 15/16] ext4: Calculate and verify superblock checksum Darrick J. Wong
[not found] ` <2882FBB2-797C-4D27-8569-B6826DD34F68@dilger.ca>
2011-09-02 18:40 ` Darrick J. Wong
2011-09-01 0:32 ` [PATCH 16/16] jbd2: Support CRC32C transaction checksums Darrick J. Wong
[not found] ` <99019900-30B1-450A-9620-E94371A30CC6@dilger.ca>
2011-09-02 18:31 ` Darrick J. Wong
2011-09-02 14:15 ` [PATCH v1 00/16] ext4: Add metadata checksumming Greg Freemyer
2011-09-02 18:22 ` Darrick J. Wong
2011-09-04 11:41 ` Martin K. Petersen
2011-09-04 16:54 ` Andi Kleen
2011-09-04 17:17 ` Martin K. Petersen
2011-09-04 17:44 ` Andi Kleen [this message]
2011-09-04 22:19 ` Martin K. Petersen
2011-09-05 18:55 ` Darrick J. Wong
2011-09-05 18:45 ` Darrick J. Wong
2011-09-06 12:59 ` Martin K. Petersen
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