> > Before we get too involved in speculating, shouldn't we actually measure
the
> > performance of 7.1 on XFS and Reiserfs? Since it's easy to disable
fsync,
> > we can test whether that's the problem. I don't think that logging file
> > systems must intrinsically give bad performance on fsync since they only
log
> > metadata changes.
> >
> > I don't have a machine with XFS installed and it will be at least a week
> > before I could get around to a build. Any volunteers?
>
> There have been multiple reports of poor PostgreSQL performance on
> Reiser and xfs. I don't have numbers, though. Frankly, I think we need
> xfs and reiser experts involved to figure out our options here.
I've done some testing to see how Reiserfs performs
vs ext2, and also various for various values of wal_sync_method while on a
reiserfs partition. The attached graph shows the results. The y axis is
transactions per second and the x axis is the transaction number. It was
clear that, at least for my specific app, ext2 was significantly faster.
The hardware I tested on has an Athalon 1 Ghz cpu and 512 MB ram. The
harddrive is a 2 year old IDE drive. I'm running Red Hat 7 with all the
latest updates, and a freshly compiled 2.4.2 kernel with the latest Reiserfs
patch, and of course PostgreSQL 7.1. The transactions were run in a loop,
700 times per test, to insert sample data into 4 tables. I used a PHP script
running on the same machine to do the inserts.
I'd be happy to provide more detail or try a different variation if anyone
is interested.
- Joe
