FreeBSD mysql Benchmark on 4BSD/ULE scheduler and i386/amd64
kris at obsecurity.org
Wed Mar 14 16:27:00 UTC 2007
On Wed, Mar 14, 2007 at 09:31:24AM +0100, Alban Hertroys wrote:
> On Mar 14, 2007, at 1:55, Kris Kennaway wrote:
> >>This being mysql, the number of processors isn't going to matter
> >>much, no matter how many connections you have. Mysql doesn't scale
> >>very well to multiple cpu's.
> >This might be standard dogma, but it also appears not to be true:
> > http://people.freebsd.org/~kris/scaling/mysql.html
> Interesting. Results I have seen using a 16 CPU SGI Altex(?) showed
> an almost linear rise for postgres while mysql topped off after about
> 4 threads. Sorry, don't have the URL at hand (I probably still have
> it in my work mail).
OK, based on the above results you already know it's at least partly
incorrect on FreeBSD with our scalability fixes. i.e. it is not a
limitation of mysql itself.
> Now this may well have been a version before 5.0.33. I'm not sure
> what OS was used either, I suppose it was either Irix or Linux.
> Now I am curious whether the same performance drop on Linux would
> occur with a postgres benchmark. It probably will, but if not it
> seems like there's a problem in the way that mysql and linux interact.
The linux scaling problem was traced to glibc malloc, so postgresql
may not be affected in the same way since it is not threaded.
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