From: Guillaume Smet <guillaume.smet@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Sven Geisler <sgeisler@aeccom.com>
Cc: Richard Huxton <dev@archonet.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: PostgreSQL and Xeon MP
Date: Tue, 21 Mar 2006 17:57:54 +0100
Message-ID: <1d4e0c10603210857q145542e1ve8533bbf7eea2aa1@mail.gmail.com> (raw)
In-Reply-To: <16633.1142522409@sss.pgh.pa.us>
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<1d4e0c10603160428s1a3c1f4cocbe8489634524387@mail.gmail.com>
<441963F4.1010607@aeccom.com>
<1d4e0c10603160630g7fe945ffo1d723843407ed128@mail.gmail.com>
<16633.1142522409@sss.pgh.pa.us>
On 3/16/06, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Can you try strace'ing some of the backend processes while the system is
> behaving like this? I suspect what you'll find is a whole lot of
> delaying select() calls due to high contention for spinlocks ...
As announced, we have migrated our production server from 7.4.8 to
8.1.3 this morning. We did some strace'ing before the migration and
you were right on the select calls. We had a lot of them even when the
database was not highly loaded (one every 3-4 lines).
After the upgrade, we have the expected behaviour with a more linear
scalability and a growing cpu load when the database is highly loaded
(and no cpu idle anymore in this case). We have fewer context switches
too.
8.1.3 definitely is far better for quad Xeon MP and I recommend the
upgrade for everyone having this sort of problem.
Tom, thanks for your great work on this problem.
--
Guillaume
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To: pgsql-performance@postgresql.org
Cc: guillaume.smet@gmail.com, tgl@sss.pgh.pa.us, sgeisler@aeccom.com, dev@archonet.com
Subject: Re: PostgreSQL and Xeon MP
In-Reply-To: <1d4e0c10603210857q145542e1ve8533bbf7eea2aa1@mail.gmail.com>
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