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
Mark,
What do you think is causing the step changes at 30+ and 60+ minutes on
these tests?
I'm at a loss to explain this myself. The increase in the i/o wait and
decrease in the response time charts looks backwards to me. And the
vmstat charts show that the i/o seems fairly consistent other than
spikes in i/o chart. It sort of looks like the operating system stopped
doing something but I'm not sure how to isolate that any further.
Anyone else have a theory?
Mark
---------------------------(end of broadcast)---------------------------
TIP 6: explain analyze is your friend
