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Date:      Sat, 28 Jun 2014 12:08:39 +0200
From:      Palle Girgensohn <girgen@pingpong.net>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>, "performance@freebsd.org" <performance@freebsd.org>
Subject:   Re: PostgreSQL performance on FreeBSD
Message-ID:  <35090A62-2DB8-493C-A5ED-ADB1BC193640@pingpong.net>
In-Reply-To: <20140627163407.GX93733@kib.kiev.ua>
References:  <20140627125613.GT93733@kib.kiev.ua> <201406271057.53599.jhb@freebsd.org> <20140627163407.GX93733@kib.kiev.ua>

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27 jun 2014 kl. 18:34 skrev Konstantin Belousov <kostikbel@gmail.com>:

> On Fri, Jun 27, 2014 at 10:57:53AM -0400, John Baldwin wrote:
>> On Friday, June 27, 2014 8:56:13 am Konstantin Belousov wrote:
>>> Hi,
>>> I did some measurements and hacks to see about the performance and
>>> scalability of PostgreSQL 9.3 on FreeBSD, sponsored by The FreeBSD
>>> Foundation.
>>>=20
>>> The results are described in https://kib.kiev.ua/kib/pgsql_perf.pdf.
>>> The uncommitted patches, referenced in the article, are available as
>>> https://kib.kiev.ua/kib/pig1.patch.txt
>>> https://kib.kiev.ua/kib/patch-2
>>=20
>> Did you run the same benchmark on the same hardware with any other OS's t=
o=20
>> compare results?
>=20
> No.
>=20
> FWIW, before the failing after the 30 clients is corrected, I do not
> think it is much interesting to do such comparision.

This is great work!

Does anybody know how far back in FreeBSD versions using posix semaphore ins=
tead of sysv would make a difference?  It seems we need a rather current ver=
sion? 8.x did not support it at all, at some point at lest, and in 9 it was b=
uggy. I could add he patch-2 to the port, but I reckon it needs a conditiona=
l based on FreeBSD version?

The clang bug should go upstreams, right?

I have seen similar curves, presented by Greg Smith (PostgreSQL hacker) wher=
e he concluded that there is no point in running more than 50 concurrent con=
nections. This was for Linux. In your measures, the knee is at 30. That's sa=
id, FreeBSD could and should do better, but probably there is a limit where t=
here will be a knee in the graph and performance will drop. It should be mor=
e than 30, though, as you rightly commented.

Do you any ideas to pursue this further apart from complicated rewrites like=
 DragonFly?

Palle=



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