General Mysql Performance Question

Kris Kennaway kris at
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.


More information about the freebsd-questions mailing list