Comments on: On checksums http://dom.as/2008/05/29/on-checksums/ Sat, 17 Dec 2011 20:14:59 +0000 hourly 1 http://wordpress.com/ By: Domas Mituzas http://dom.as/2008/05/29/on-checksums/#comment-1307 Fri, 30 May 2008 21:27:04 +0000 http://dammit.lt/?p=142#comment-1307 Matt, –skip-innodb-checksums

Yeah, ZFS can be fast, but so can be userland checksums, if implemented properly. The way currently InnoDB does it may not be that easy to optimize at compiler level – I’ll have to check it more.

]]> By: Matt Ingenthron http://dom.as/2008/05/29/on-checksums/#comment-1306 Fri, 30 May 2008 17:09:33 +0000 http://dammit.lt/?p=142#comment-1306 Is there an option to turn it off entirely if the filesystem is checksumming? I keep meaning to look into this.

For instance ZFS always checksums and uses encryption like algorithms and CPU features to be extremely efficient about it. With that big non-Open Source DB, turning off the DB checksum was a good win. Neel has a blog on this somewhere…

]]> By: Domas Mituzas http://dom.as/2008/05/29/on-checksums/#comment-1305 Fri, 30 May 2008 10:25:21 +0000 http://dammit.lt/?p=142#comment-1305 Interesting, SSE4.2 adds CRC32-on-chip. It also adds more nice functions, that can be used for strlen() and similar optimizations. Nehalem will be kickass for databases, if they manage to use the feature set.

]]> By: Peter Zaitsev http://dom.as/2008/05/29/on-checksums/#comment-1304 Fri, 30 May 2008 05:43:37 +0000 http://dammit.lt/?p=142#comment-1304 Indeed it is not 2 times gain but there is some to save,
Another question is if checksumming algorithm is as efficient as possible ?
Could be it could be replaced with some other CPU Cache scratch free SSE based algorithm for better performance.
I know Linux kernel uses these for RAID checksum computation when available.

]]> By: Arjen Lentz http://dom.as/2008/05/29/on-checksums/#comment-1303 Thu, 29 May 2008 21:56:21 +0000 http://dammit.lt/?p=142#comment-1303 Good moment perhaps to mention the checksum algorithm also, people will be curious and one can always discuss… just paste code snipped w/ comments?

]]> By: Mark Callaghan http://dom.as/2008/05/29/on-checksums/#comment-1302 Thu, 29 May 2008 20:56:59 +0000 http://dammit.lt/?p=142#comment-1302 I hope you get less than half because the old style checksum is computed over much less of the page than the new style checksum.

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