From: Greg Smith <gsmith@gregsmith.com>
To: Postgresql Performance list <pgsql-performance@postgresql.org>
Subject: Re: New to PostgreSQL, performance considerations
Date: Thu, 14 Dec 2006 10:00:14 -0500 (EST)
Message-ID: <Pine.GSO.4.64.0612140950460.11833@westnet.com> (raw)
In-Reply-To: <E1GuYSE-000378-Sk@elasmtp-spurfowl.atl.sa.earthlink.net>
References: <C1A31C39.15548%llonergan@greenplum.com>
<457EA39E.1020207@streppone.it>
<20061212124803.GA29167@mathom.us>
<4580264F.8030109@streppone.it>
<E1GuYSE-000378-Sk@elasmtp-spurfowl.atl.sa.earthlink.net>
On Wed, 13 Dec 2006, Ron wrote:
> The slowest results, Michael's, are on the system with what appears to be the
> slowest CPU of the bunch; and the ranking of the rest of the results seem to
> similarly depend on relative CPU performance. This is not what one would
> naively expect when benching a IO intensive app like a DBMS.
pgbench with 3000 total transactions and fsync off is barely doing I/O to
disk; it's writing a bunch of data to the filesystem cache and ending the
benchmark before the data even makes it to the hard drive. This is why
his results become completely different as soon as the number of
transactions increases. With little or no actual disk writes, you should
expect results to be ranked by CPU speed.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
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To: pgsql-performance@postgresql.org
Cc: gsmith@gregsmith.com
Subject: Re: New to PostgreSQL, performance considerations
In-Reply-To: <Pine.GSO.4.64.0612140950460.11833@westnet.com>
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