On Tue, 02 May 2006 10:52:38 +0100 Simon Riggs <[EMAIL PROTECTED]> wrote:
> On Sun, 2006-04-30 at 22:14 -0700, Mark Wong wrote: > > I would have gotten this out sooner but I'm having trouble with our > > infrastructure. Here's a link to a table of data I've started putting > > together regarding XLOG_BLCKSZ and wal_buffers on a 4-way Opteron > > system: > > http://developer.osdl.org/markw/pgsql/xlog_blcksz.html > > > > There are a couple of holes in the table but I think it shows enough > > evidence to say that with dbt2 having a larger XLOG_BLCKSZ improves the > > overall throughput of the test. > > > > I'm planning on continuing to increase XLOG_BLCKSZ and wal_buffers to > > determine when the throughput starts to level out or drop off, and then > > start experimenting with varying BLCKSZ. Let me know if there are other > > things that would be more interesting to experiment with first. > > IMHO you should be testing with higher wal_buffers settings. ISTM likely > that the improved performance is due to there being more buffer space, > rather than actually improving I/O. Setting wal_buffers to something > fairly high say 4096 would completely remove any such effect so we are > left with a view on the I/O. I ran another few tests at the 600 scale factor just in case I was getting close to peaking at 500 warehouses. (Link above has updated data.) With wal_buffers set to 4096 the difference between 2048, 8192, and 32768 seem negligible. Some of the disks are at 90% utilization so perhaps I need to take a close look to make sure none of the other system resources are pegged. Thanks, Mark ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
