Re: Fine-grained locking for POSIX local sockets (UNIX domain sockets)

On Sun, May 07, 2006 at 07:16:34PM +0100, Robert Watson wrote:

On Sun, 7 May 2006, Sven Petai wrote:

I performed tests on a 4 * dualcore 2Ghz opteron system (so 8 cores in
total).

In general with 10 parallel smacker threads the performance seems to go up
with your patch by ~44% and with 100 parallel threads it goes down ~25%

This is an interesting effect I need to explore. Kris reported much
increased contention on locks within the process (between threads) when
running with my patch. It would be interesting to know what the effect on
average query time is -- perhaps it has gone down and we're looking at
increased scheduler related contention.

I noticed the results in the tests seem somewhat variable. I've noticed
that MySQL bennchmarking is heavily affected by test run time and order.
It's not atypical when running a series of identical tests to see a first
result half the end rate, a second result *better* than the end rate, and
then it balance out between the two. For example, I see the following on a

Also, I see a slow but statistically significant deterioration in
performance over time. Maybe mysql's memory is getting fragmented or
something.

Kris

Attachment: pgpohc5kILNiO.pgp
Description: PGP signature