General Mysql Performance Question

[Paul A. Procacci]

Hey All,

Recently I've been asked to do performance testing of postgres and mysql 
on FreeBSD.  Kris' page 
(http://people.freebsd.org/~kris/scaling/mysql.html) was extremely 
useful in giving me a starting point for my own comparisons.  
Additionally, his name is splattered all over the web with patches, 
tuning tips, etc.  For that, I thank you Kris.  With that said, I've 
come across something that I can not find the answer to and I'm hoping I 
have missed something incredibly simple.  If this has been mentioned 
before, then I apologize in advance.

http://paul.procacci.me/benchmarks/freebsd7-Release.html

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.

Thanks in advance,
~Paul