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Date: Wed, 27 Aug 2003 13:28:55 -0400 (EDT)
From: Robert Watson <rwatson@FreeBSD.ORG>
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To: David Schultz <das@FreeBSD.ORG>
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cc: freebsd-fs@FreeBSD.ORG
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cc: Bill Moran <wmoran@potentialtech.com>
Subject: Re: Performance tests I did with FreeBSD, Linux and PostgreSQL
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On Tue, 26 Aug 2003, David Schultz wrote:

> On Tue, Aug 26, 2003, Bill Moran wrote:
> > Like all benchmarks, I doubt these are perfect (or even close) examples
> > of real-world use.
> > 
> > However, in the hopes that they will be useful for improving FreeBSD, I
> > present them to the community.
> > 
> > http://www.potentialtech.com/wmoran/postgresql.php
> > 
> > Intelligent comments are welcome.
> 
> Well, a little trussing revealed that pgsql uses a block size of 8K,
> which can be a significant pessimization when the filesystem block size
> is 16K, which is the default in FreeBSD!  ext2fs uses 4K blocks and
> reiserfs uses extents, so those filesystems would not suffer from that
> problem.  You might consider trying your test on a UFS filesystem with
> 8K blocks, or you could tune pgsql to use a different block size.  (For
> pgsql, I think the appropriate tunable is BLCKSZ in include/pg_config.h. 
> You'll have to recompile it and create a new database.) 

I wonder if it would benefit us to do some tweaks to Postgres to tune the
pgsql block size to the file system it's running on, and get it integrated
back into the distribution....  As disks get bigger, a 16k block size is
going to become more common, so this won't just hit FreeBSD, I expect.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Network Associates Laboratories