Date: Fri, 04 Jan 2008 20:33:08 +0100 From: Kris Kennaway <kris@FreeBSD.org> To: Gergely CZUCZY <phoemix@harmless.hu> Cc: Jeff Roberson <jroberson@chesapeake.net>, freebsd-performance@freebsd.org Subject: Re: mysql scaling questions Message-ID: <477E89F4.1080605@FreeBSD.org> In-Reply-To: <20080104133028.GA89602@harmless.hu> References: <20071201163334.GA21709@harmless.hu> <200712012055.lB1Kt5IQ005728@lava.sentex.ca> <20071201205609.GA54238@harmless.hu> <200712012108.lB1L8qAd005766@lava.sentex.ca> <20071201211012.GA55519@harmless.hu> <20071201122122.S884@192.168.1.107> <20071204130810.GA77186@harmless.hu> <47779AA7.2060801@FreeBSD.org> <20071230132451.GA61295@harmless.hu> <477D5927.4030100@FreeBSD.org> <20080104133028.GA89602@harmless.hu>
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Gergely CZUCZY wrote: > On Thu, Jan 03, 2008 at 10:52:39PM +0100, Kris Kennaway wrote: >> Gergely CZUCZY wrote: >> >>>> * Compare to my config file here: >>>> >>>> http://people.freebsd.org/~kris/scaling/my.cnf >>>> >>>> The default mysql config has very poor performance for innodb (you need at least innodb_thread_concurrency = 0 to disable some mysql brain-death). >>>> Maybe tuning is required for myisam also. >>>> >>>> * Also make sure you are using identical config settings on the two systems. >>> http://phoemix.harmless.hu/mysql/ verify yourself. Only the paths are >>> updated, but the main parameters are just the same. >> You are not in fact using the same config parameters as I am. When I use your config file I see a large performance loss when I run locally even with >> innodb. > So, the updated config is here: > http://phoemix.harmless.hu/mysql/my.cnf.kris > > I've migrated the values from your config. > > And the plot is here: > http://phoemix.harmless.hu/mysql/rw-kris.png > > I"ve also plotted a current production system, which crashes around 96 threads in > the test, or so. That's a Linux-2.6.12 and MySQL 5.0.22, so it should be quite unoptimized > compared to any recent version of anything. > > As it seems, you were right. These adjustments made a very slight performance boost, around > 5%. But it's still lagging behind. > > Again, this is MyISAM, not innodb. The "tc4" and "tc16" strings mean the thread_concurrency > is either set to 4 or 16. Your config had 16, but I've googled for it, and some resources > suggested setting that to CPUs*2, and that's 4 in my case. > > I've updated the MySQL version on FreeBSD to 5.0.51, and will try to get this version > on linux also, and do a comparision with that one, too. > > Sincerely, > > Gergely Czuczy > mailto: gergely.czuczy@harmless.hu > OK. The caching problem with myisam is unrelated to the other config changes then. Kris
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