Date: Fri, 29 Aug 2008 09:52:09 +0200 From: Kris Kennaway <kris@FreeBSD.org> To: "Paul A. Procacci" <pprocacci@datapipe.com> Cc: FreeBSD <freebsd-questions@freebsd.org> Subject: Re: General Mysql Performance Question Message-ID: <48B7AAA9.8000706@FreeBSD.org> In-Reply-To: <48B7A67F.8050204@datapipe.com> References: <48B7A67F.8050204@datapipe.com>
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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
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