FreeBSD MySQL still WAY slower than Linux

[Michael Schuh]

Hello,

yes random IO is more targetted to Databases.
noop, i have the installation always made in the same way, and i have respected
the different diskperformace in different disk-parts.....
this was the reason for

#cd /; 

at the beginning of my tests.
In the first test i have me shooting self in my foot and i bites me in
my ass :-)))
 
my suggestion going more in the direction...first solve all disk(ata) related
performace issues, then test the mysql-performaces issues again to secure
that you are not lying on an mixing of many problems.... :-)

I think this was better then seek around corners that are not so relevant... or
the result is not so dramatically....

greetings

Michael


2005/6/20, Mark Kirkwood <markir at paradise.net.nz>:
> Michael Schuh wrote:
> >
> >
> > My results was that RELENG_5 is half as RELENG_4 fast by disk-access
> > (ata-related).
> >
> > I have seen that RELENG_5 with GENERIC Kernel and only modified option HZ=2000.
> >
> > the spread begind with Gentoo (mentoided from me as the slowest, but
> > errare humanum est)
> >
> > Gentoo : 100% time consumption
> > RELENG_4: 67% time consumtion
> > DrangonFly Rel1.2 69-72% time consumption (i think preemtion)
> > RELENG_5 134% time consumtion
> >
> > these tests are made on physically the same Hardware (real, not equal
> > system, same system, same disk, same RAM) with the command:
> >
> > # cd /; /usr/bin/time dd if=/dev/zero bs=1024 count=1024k of=zerofile;
> >
> >
> 
> You have shown that sequential IO is slower in RELENG_5 (I think others
> have observed this also - check out Google)...However, random IO is
> often more important for databases, and RELENG_5 can be faster than
> RELENG_4 (try out iozone, it makes testing this easy).
> 
> Also note that if your operating systems are installed in different
> parts of the same disk, then this will effect your results too - as some
> parts are faster than others.
> 
> With respect to Mysql performance, I would suspect threading or
> threading/kernel interaction as the culprit. (That reminds me, I don't
> recall seeing the original poster re-doing the tests with 6.0-CURRENT -
> that would be interesting).
> 
> cheers
> 
> Mark
> 
>