On Mon, 19 May 2008, Matthew Wakeling wrote:
Does it really take that long to zero out 8kB of RAM? I thought CPUs were really quick at doing that!
You don't get the whole CPU--you get time slices of one. Some of the cases complaints have come in about have over a thousand connections all fighting for CPU time, and making every one of them block for one guy who needs to fiddle with memory for a while can be a problem. If you're unlucky you won't even be on the same CPU you started on each time you get a little check of time, and you'll run at the speed of RAM rather than that of the CPU--again, fighting for RAM access with every other process on the server.
The real question in my mind is why this turns into a bottleneck before the similar task of cleaning the 16MB XLOG segment does. I expected that one would need to be cracked before the CLOG switch time could possibly be an issue, but reports from the field seem to suggest otherwise.
-- * Greg Smith [EMAIL PROTECTED] http://www.gregsmith.com Baltimore, MD -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
