Date: Fri, 17 Jun 2005 10:30:25 -0500 From: Greg Barniskis <nalists@scls.lib.wi.us> To: "J. T. Farmer" <jfarmer@goldsword.com> Cc: uzi@bmby.com, freebsd-stable@freebsd.org Subject: Re: FreeBSD MySQL still WAY slower than Linux Message-ID: <42B2EC91.8070800@scls.lib.wi.us> In-Reply-To: <42B2E9B5.7090803@goldsword.com> References: <6.2.1.2.2.20050617103807.058c6fa8@mail.distrust.net> <005c01c57354$3e877900$fe00a8c0@uzi> <42B2E9B5.7090803@goldsword.com>
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J. T. Farmer wrote: > Uzi wrote: > >> [...] >> >>> super-smack select-key >>> 5.4-RELEASE ~20,000 queries/second >>> 6.0-CURRENT ~24,000 queries/second >>> CentOS w/async ~36,000 queries/second >>> CentOS w/sync ~26,000 queries/second >>> >>> super-smack update-select >>> 5.4-RELEASE ~4,000 queries/second >>> 6.0-CURRENT ~4,500 queries/second >>> CentOS w/async ~7,500 queries/second >>> CentOS w/sync ~750 queries/second >>> >>> That last CentOS number is not a typo, it was an order of magnitude >>> slower. I didn't try other file systems on CentOS, just the default >>> ext3. It's possible that reiserfs or xfs might not be as affected by >>> switching from async to sync. >>> >>> So my production server is now happily running mysql 4.1 on >>> 6.0-CURRENT :). >> >> >> I don't get it. >> You get 30% less perfomance, running a non-production release for >> production, and happy about it? > > > > Try reading it again. The last time I checked, 24k queries/sec _is_ > faster than > 20k queries/sec. And 4.5k queries/sec is faster than 4.0k queries/sec. I think he meant comparing 36,000 on CentOS (async) to 24,000 on CURRENT (sync). I wondered that myself, and having searched out the answer I find that it is declared in http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/configtuning-disk.html that async provides fast writes at the cost of "no guarantee at all for a consistent state of the filesystem". So, you choose: fast but not so reliable writes, or slower writes with fast, reliable disaster recovery. Thanks to the FreeBSD team for choosing the sensible default, even if it results in the occasional "Linux is faster!" debate. Dang smirky penguins... you're flightless I tell ya, flightless. =) -- Greg Barniskis, Computer Systems Integrator South Central Library System (SCLS) Library Interchange Network (LINK) <gregb at scls.lib.wi.us>, (608) 266-6348
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