Re: SMP performance degradation with sysbench

Eric Dumazet
2007-03-14T01:00:51Z

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 ?