From: Greg Smith <gsmith@gregsmith.com>
To: pgsql-performance@postgresql.org
Subject: Re: Strange behavior: pgbench and new Linux kernels
Date: Thu, 17 Apr 2008 20:26:25 -0400 (EDT)
Message-ID: <Pine.GSO.4.64.0804172002010.15803@westnet.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0804171840180.20402@aragorn.flymine.org>
References: <Pine.GSO.4.64.0804170230180.26917@westnet.com>
<fd145f7d0804171009h7658d3bbqf099b5c0e9235268@mail.gmail.com>
<Pine.LNX.4.64.0804171840180.20402@aragorn.flymine.org>
On Thu, 17 Apr 2008, Matthew wrote:
> The last message in the thread says that 2.6.25-rc6 has the problem nailed.
> That was a month ago. So I guess, upgrade to 2.6.25, which was released
> today.
Ah, even more support for me to distrust everything I read. The change
has flattened out things, so now the pgbench results are awful everywhere.
On this benchmark 2.6.25 is the worst kernel yet:
-bash-3.00$ pgbench -S -c 4 -t 10000 pgbench | grep excluding
tps = 8619.710649 (excluding connections establishing)
tps = 8664.321235 (excluding connections establishing)
tps = 8671.973915 (excluding connections establishing)
(was 18388 in 2.6.9 and 16621 in 2.6.23-3)
-bash-3.00$ pgbench -S -c 8 -t 10000 pgbench | grep excluding
tps = 9011.728765 (excluding connections establishing)
tps = 9039.441796 (excluding connections establishing)
tps = 9206.574000 (excluding connections establishing)
(was 15760 in 2.6.9 and 15551 in 2.6.23-3)
-bash-3.00$ pgbench -S -c 16 -t 10000 pgbench | grep excluding
tps = 7063.710786 (excluding connections establishing)
tps = 6956.266777 (excluding connections establishing)
tps = 7120.971600 (excluding connections establishing)
(was 14148 in 2.6.9 and 7311 in 2.6.23-3)
-bash-3.00$ pgbench -S -c 32 -t 10000 pgbench | grep excluding
tps = 7006.311636 (excluding connections establishing)
tps = 6971.305909 (excluding connections establishing)
tps = 7002.820583 (excluding connections establishing)
(was 13647 in 2.6.9 and 7141 in 2.6.23-3)
This is what happens when the kernel developers are using results from a
MySQL tool to optimize things I guess. It seems I have a lot of work
ahead of me here to nail down and report what's going on here.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: gsmith@gregsmith.com
Subject: Re: Strange behavior: pgbench and new Linux kernels
In-Reply-To: <Pine.GSO.4.64.0804172002010.15803@westnet.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox