General Mysql Performance Question
kris at FreeBSD.org
Fri Aug 29 07:52:15 UTC 2008
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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