Re: SMP performance degradation with sysbench

Nish Aravamudan
2007-03-14T01:09:46Z

On 3/13/07, Eric Dumazet <dada1@cosmosbay.com> wrote:
> Nish Aravamudan a écrit :
> > On 3/12/07, Anton Blanchard <anton@samba.org> wrote:
> >>
> >> Hi Nick,
> >>
> >> > Anyway, I'll keep experimenting. If anyone from MySQL wants to help
> >> look
> >> > at this, send me a mail (eg. especially with the sched_setscheduler
> >> issue,
> >> > you might be able to do something better).
> >>
> >> I took a look at this today and figured Id document it:
> >>
> >> http://ozlabs.org/~anton/linux/sysbench/
> >>
> >> Bottom line: it looks like issues in the glibc malloc library, replacing
> >> it with the google malloc library fixes the negative scaling:
> >>
> >> # apt-get install libgoogle-perftools0
> >> # LD_PRELOAD=/usr/lib/libtcmalloc.so /usr/sbin/mysqld
> >
> > Quick datapoint, still collecting data and trying to verify it's
> > always the case: on my 8-way Xeon, I'm actually seeing *much* worse
> > performance with libtcmalloc.so compared to mainline. Am generating
> > graphs and such still, but maybe someone else with x86_64 hardware
> > could try the google PRELOAD and see if it helps/hurts (to rule out
> > tester stupidity)?
>
> I wish I had a 8-way test platform :)
>
> Anyway, could you post some oprofile results ?

Hopefully soon -- want to still make sure I'm not doing something
dumb. Am also hoping to get some of the gdb backtraces like Anton had.

Thanks,
Nish