Re: Perf regression in 2.6.32 (Ubuntu 10.04 LTS)

On 12/09/10 23:31, Domas Mituzas wrote:
> I've been playing around today a lot with sysbench, and observed that 2.6.32 kernel supplied by Ubuntu is having perf regression with PG (which does not affect MySQL), compared to 2.6.28 builds I have.
> What I observed can be seen in a paste at http://p.defau.lt/?8_GQV82Pz3_SDZbNOdP93Q (db12 is 2.6.28, db20 is 2.6.32 - 2.6.32-24-server).
>
> Machines are two socket quad-opterons 2356s.
>
> oprofile output can be seen at http://p.defau.lt/?OIR1vDFK4cze_fmBTQbV9w - system has>20% of idle cpu, which is somewhere in the top symbol :)

Can you run oprofile on the older kernel, so that we can compare and see
where the time is spent?

Looks like over 7% of the time is spent in s_lock, which suggests some
change in behavior in context switching or something like that, but
let's see what the old profile looks like.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com