General Mysql Performance Question
Paul A. Procacci
pprocacci at datapipe.com
Fri Aug 29 08:00:26 UTC 2008
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.
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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.
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