Horton

Re: Perfomance degradation 9.3 (vs 9.2) for FreeBSD

Francois Tigeot <ftigeot@wolfpond.org>

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From: Francois Tigeot <ftigeot@wolfpond.org>
To: Palle Girgensohn <girgen@FreeBSD.org>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Francois Tigeot <ftigeot@wolfpond.org>
Date: 2014-04-20T10:19:55Z
Lists: pgsql-hackers

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  1. Add shared_memory_type GUC.

Hi,

On Sun, Apr 20, 2014 at 11:24:38AM +0200, Palle Girgensohn wrote:
> 
> I see performance degradation with PostgreSQL 9.3 vs 9.2 on FreeBSD, and I'm wondering who to poke to mitigate the problem. In reference to this thread [1], who where the FreeBSD people that Francois mentioned?

At least one FreeBSD hacker came to discuss it on the #dragonflybsd irc
channel and tried to run the benchmark on a 80-core machine.

I didn't keep logs and don't remember his/their name(s) but there was
definitely some FreeBSD effort at the time to investigate and fix things.

> If mmap needs to perform well in the kernel, I'd like to know of someone with FreeBSD kernel knowledge who is interested in working with mmap perfocmance. If mmap is indeed the cuplrit, I've just tested 9.2.8 vs 9.3.4, I nevere isolated the mmap patch, although I believe Francois did just that with similar results.

I did test the 9.3 -devel branch before and after the SysV shared memory =>
mmap commit. The performance degradation was visible.

I recently ran a few benchmarks of PostgreSQL 9.3 with different operating systems
including DragonFly 3.6 and FreeBSD 10. You may be interested in the results:

http://lists.dragonflybsd.org/pipermail/users/2014-March/128216.html

-- 
Francois Tigeot