mysql scaling questions

[Kris Kennaway]

Gergely CZUCZY wrote:
> On Sun, Dec 30, 2007 at 02:35:56PM +0100, Kris Kennaway wrote:
>> Gergely CZUCZY wrote:
>>
>>>> I appreciate that you might be constrained by local requirements, but it's really not meaningful to compare different mysql versions 
>>>> if your goal is to study OS performance.
>>> It'd be a PITA to install the both versions. Maybe now, that the ports freeze is over, i can
>>> do something. But honestly, every mysql version was faster on linux, than eny on FreeBSD,
>>> even the .22 one was faster. We start work on Jan02, I will see what can I do.
>> Regardless, we need a stable baseline to compare to.
> Cannot do it sooner then january. Any recommended versions?

Either 5.0.45 on both, or 5.0.51 on both, please.

>> Still waiting for your sysbench command lines :)
> There were 2 scripts and a sources file with options:
> 
> basicall that's everything. I know it's a but complex, but this was all behind it.

OK, that was very important since you're changing defaults.

It looks like myisam is doing huge numbers of concurrent reads of the 
same file which is running into exclusive locking in the kernel (vnode 
interlock and lockbuilder mtxpool).  Does it not do any caching of the 
data in userspace but relies on querying into the kernel every time? 
innodb doesn't have this behaviour.

Kris