On Wed, 2010-04-07 at 14:45 -0700, Craig James wrote: > On 4/7/10 2:40 PM, Joshua D. Drake wrote: > > On Wed, 2010-04-07 at 14:37 -0700, Craig James wrote: > >> Most of the time Postgres runs nicely, but two or three times a day we get > >> a huge spike in the CPU load that lasts just a short time -- it jumps to > >> 10-20 CPU loads. Today it hit 100 CPU loads. Sometimes days go by with > >> no spike events. During these spikes, the system is completely > >> unresponsive (you can't even login via ssh). > >> > >> I managed to capture one such event using top(1) with the "batch" option > >> as a background process. See output below - it shows 19 active postgress > >> processes, but I think it missed the bulk of the spike. > > > > What does iostat 5 say during the jump? > > It's very hard to say ... I'll have to start a background job to watch for a > day or so. While it's happening, you can't login, and any open windows > become unresponsive. I'll probably have to run it at high priority using > nice(1) to get any data at all during the event.
Do you have sar runing? Say a sar -A ? > > Would vmstat be informative? Yes. My guess is that it is not CPU, it is IO and your CPU usage is all WAIT on IO. To have your CPUs so flooded that they are the cause of an inability to log in is pretty suspect. Joshua D. Drake > > Thanks, > Craig > -- PostgreSQL.org Major Contributor Command Prompt, Inc: http://www.commandprompt.com/ - 503.667.4564 Consulting, Training, Support, Custom Development, Engineering Respect is earned, not gained through arbitrary and repetitive use or Mr. or Sir. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
