Date: Fri, 29 Aug 2008 03:00:09 -0500 From: "Paul A. Procacci" <pprocacci@datapipe.com> To: Kris Kennaway <kris@FreeBSD.org> Cc: FreeBSD <freebsd-questions@freebsd.org> Subject: Re: General Mysql Performance Question Message-ID: <48B7AC89.70502@datapipe.com> In-Reply-To: <48B7AAA9.8000706@FreeBSD.org> References: <48B7A67F.8050204@datapipe.com> <48B7AAA9.8000706@FreeBSD.org>
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Kris Kennaway wrote: > Paul A. Procacci wrote: >> My question is in reference to the 1st and 2nd graphs on this page. >> While testing the performance of the databases given in this graph, >> the one thing that sticks out is that when Mysql uses the myisam >> engine with the ULE schedular, performance drops quite considerably >> regardless of mysql version. The clearly shows ULE to perform worst >> at higher work loads than 4BSD, at least in this one example. >> >> Now, I read that lockmgr code is still a work in progress, but I'm >> unsure if that applies specifically to this specific problem that I'm >> providing. What I'm hoping for quite frankly is a "yes, this is >> because...." type of response. >> >> This isn't a problem per se, but rather a curiosity type of question. > > myisam has huge lock contention, so probably ULE is more efficiently > scheduling the processes and increasing contention yet further, > leading to a net drop of performance. That kind of thing is fairly > common when you have a workload with high contention; if you improve > performance at one bottleneck the performance at a later bottleneck > can get worse. Performance will still be better on other workloads, or > when further work improves the other bottlenecks. > > Kris > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to > "freebsd-questions-unsubscribe@freebsd.org" Kris, Thanks for your prompt response. I was aware that myisam had pretty huge lock contention, but didn't think ULE, because it's doing it's job better, is actually making things worse. I appreciate your insight. ~Paul
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