Fine-grained locking for POSIX local sockets (UNIX domain sockets)

Kris Kennaway kris at obsecurity.org
Sun May 7 19:59:44 UTC 2006


On Sun, May 07, 2006 at 08:57:21PM +0100, Robert Watson wrote:
> 
> >On Sun, May 07, 2006 at 10:00:41PM +0300, Sven Petai wrote:
> >
> >>The results in my mail were mean values over 2 runs,
> >>only once did I see really huge (more than 10%) differences between 
> >>several
> >>subsequent runs with same settings, this case was clearly mentioned in 
> >>the results.
> >
> >FYI, 2 is not really enough, you should do at least 10 repetitions of each 
> >test to reduce variance (which can be a lot, despite what you saw!) and so 
> >that differences between them can be accurately estimated.  Ministat is 
> >really helpful for this.
> 
> Typically, I do 12 runs of supersmack in each configuration, and discard 
> the first 2 runs in which the cache and scheduler (etc) are still settling, 
> as I'm interested in the steady state.

Yeah, forgot to mention that too.  Also keeping in mind that mysql
performance is not time-constant, e.g. you should restart it in
between test configurations instead of comparing early and late times.

Kris
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