Help for very bad perf for MySQL

Ted Mittelstaedt tedm at toybox.placo.com
Tue Nov 27 05:49:16 PST 2007



> -----Original Message-----
> From: Albert Shih [mailto:Albert.Shih at obspm.fr]
> Sent: Tuesday, November 27, 2007 5:00 AM
> To: Ted Mittelstaedt
> Cc: freebsd-questions at freebsd.org
> Subject: Re: Help for very bad perf for MySQL
>
>
>  Le 26/11/2007 à 22:34:34-0800, Ted Mittelstaedt a écrit
> >
> >
>
> Sorry yeasterday I don't have time to answer you.
>
> > >
> > > I've already send a message. But I don't receive any answer :-(.
> > > I try again
> > > and hope there more solution
> > >
> > > I've a bi-proc single core Xeon 3.2ghz with FreeBSD 6.2, I'm
> running Mysql
> > > 5.X on this server and the performance of MySQL is very bad. For some
> > > complexe select I've got ~6secondes (on some basic Linux it's take 0.6
> > > sec). And I think this is nothing about thead (that's mean I
> don't think
> > > FreeBSD 7.0 can solve my problem) because it's just for one select.
> > >
> > > The server have two SAS 10 000 tr/m disks.
> > >
> > > Anyone have some advise to tunning FreeBSD or MySQL for increase
> > > the perf ?
> > >
> >
> > Start with the obvious stuff first.  How big is the database?  How
> > big is system ram?  If you have less ram than you have database then
> > mysql will have to go to the hard disk for the select which will kill
> > it's performance.
> >
> Well :
>
> Database size ~ 180Mo
> Ram of server = 4 Go
> 2 processeurs.
> Nothing run on this server (charge is near zero).
>
> The disk I/O is running very fast.
> The make buildworld is fast too (I don't have measure but it's «fast» ;-))
>

Is Hyperthreading enabled  (by default it is not under
FreeBSD)  mysql is heavily dependent on threading, if it is not
built and linked into the freebsd threads package you will get
poor performance.  Some folks have installed the linux compat libs
and linked mysql into the linux threads package and reported good
results.

Ted



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