MySQL benchmarks
Antony T Curtis
antony.t.curtis at ntlworld.com
Thu Feb 10 21:34:56 GMT 2005
On Wed, 2005-02-09 at 15:37 -0700, Scott Long wrote:
> Miguel Mendez wrote:
>
> > Hi all,
> >
> > Someone has posted a link to a newsforge article on the NetBSD lists
> > that benchmarks MySQL performance on several systems, you can see it at:
> >
> > http://software.newsforge.com/article.pl?sid=04/12/27/1243207&from=rss
> >
> > I don't know how much Linux-specific code there is in MySQL because,
> > honestly, I always try to avoid it and go with PostgreSQL, but perhaps
> > somebody with more MySQL-fu can fill in the blanks and confirm that the
> > better performance seen on Linux systems is due to how the software is
> > designed and not so much related to FreeBSD per se.
> >
> > Cheers,
>
> There has long been speculation that Linux cuts corners on these tests
> by ignoring things like fsync. One thing that I've been meaning to do
> for a while is to ktrace some of the mysql benchmarks and see what
> exactly is going on, then compare that to a similar ktrace run under
> Linux. If it turns out that there are lots of synchronization calls
> (i.e. fsync-like calls), try stubbing them out in FreeBSD and see if it
> brings you any closer to the linux scores.
>
> An easier but also informative test would be to remount the database
> filesystem as async-noatime-nosoftupdates and see how it compares.
The test was performed using Innodb... and if the define is available,
it usually opens its filestore with the O_DIRECT flag. Also, expect
plenty of fsync() calls. If Linux is returning from the write() calls
without pushing the data to disk, that itself will give it a sizable
lead.
If I remember correctly, MyISAM with skip-locking should rarely use
fsync() calls... so if possible, the test could be re-run using MyISAM
tables to see if there is any performance difference.
I have not personally done any performance comparisons between FreeBSD
and Linux in more than a year but the last time I compared FreeBSD 5
pthreads and Linux, Linux does appear to have the edge on thread
creation and synchronisation. However, I have switched all my machines
to be running FreeBSD since... (rpm hell experience during upgrading)
YMMV, opinions are mine and not my employer, yadda yadda yadda...
--
Antony T Curtis, BSc. UNIX, Linux, *BSD, Networking
antony.t.curtis at ntlworld.com C++, J2EE, Perl, MySQL, Apache
IT Consultancy.
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