On Thu, 2006-06-01 at 16:46 -0700, Mark Wong wrote: > Simon Riggs wrote: > > On Wed, 2006-05-10 at 09:55 -0700, Mark Wong wrote: > >> Simon Riggs wrote: > >>> Could you turn full_page_writes = off and do a few more tests? I think > >>> the full page writes is swamping the xlog and masking the performance we > >>> might see for normal small xlog writes. > >>> I'd try XLOG_BLCKSZ = 4096 and 8192 to start with. Thanks. > >> Ok, got data for XLOG_BLCKXZ at 4096, 8192, and 32768 with > >> full_page_wirtes = off. The new data is at the bottom of the page: > >> http://developer.osdl.org/markw/pgsql/xlog_blcksz.html > > > > What do you think is causing the step changes at 30+ and 60+ minutes on > > these tests? > > I took some time to start charting the sar data and to break down the > iostat data by tablespaces. I've updated the web pages form the link > above. Well, none of the charts helped me make any better guesses but > perhaps someone else will see something. > > When I get back from my short break, I'm planning on taking a look at > Tau, a project from the University of Oregon > (http://www.cs.uoregon.edu/research/tau/home.php) that's capable of > breaking down profiles per process and gathering hardware counters. I'm > hoping that will shed some light on the behavior.
Sounds useful. Let me know what you find. -- Simon Riggs EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq