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
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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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