Re: SMP performance degradation with sysbench

Hiro Yoshioka
2007-02-27T00:32:13Z

Howdy,

MySQL 5.0.26 had some scalability issues and it solved since 5.0.32
http://ossipedia.ipa.go.jp/capacity/EV0612260303/
(written in Japanese but you may read the graph. We compared
5.0.24 vs 5.0.32)

The following is oprofile data
==> cpu=8-mysql=5.0.32-gcc=3.4/oprofile-eu=2200-op=default-none/opreport-l.txt
<==
CPU: Core Solo / Duo, speed 2666.76 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Unhalted clock cycles) with a unit
mask of 0x00 (Unhalted core cycles) count 100000
samples % app name symbol name
47097502 16.8391 libpthread-2.3.4.so pthread_mutex_trylock
19636300 7.0207 libpthread-2.3.4.so pthread_mutex_unlock
18600010 6.6502 mysqld rec_get_offsets_func
18121328 6.4790 mysqld btr_search_guess_on_hash
11453095 4.0949 mysqld row_search_for_mysql

MySQL tries to get a mutex but it spends about 16.8% of CPU on 8 core
machine.

I think there are a lot of room to be inproved in MySQL implementation.

On 2/27/07, Dave Jones <davej@redhat.com> wrote:
> On Mon, Feb 26, 2007 at 04:04:01PM -0600, Pete Harlan wrote:
> > On Tue, Feb 27, 2007 at 12:36:04AM +1100, Nick Piggin wrote:
> > > I found a couple of interesting issues so far. Firstly, the MySQL
> > > version that I'm using (5.0.26-Max) is making lots of calls to
> >
> > FYI, MySQL fixed some scalability problems in version 5.0.30, as
> > mentioned here:
> >
> > http://www.mysqlperformanceblog.com/2007/01/03/innodb-benchmarks/
> >
> > It may be worth using more recent sources than 5.0.26 if tracking down
> > scaling problems in MySQL.
>
> The blog post that originated this discussion ran tests on 5.0.33
> Not that the mysql version should really matter. The key point here
> is that FreeBSD and Linux were running the *same* version, and
> FreeBSD was able to handle the situation better somehow.
>
> Dave
>
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Regards,
Hiro
--
Hiro Yoshioka
mailto:hyoshiok at miraclelinux.com