Based on what other people have posted, hyperthreading seems not to be beneficial for postgres -- try searching through the archives of this list. (And then turn it off and see if it helps.) You might also post a few details: config settings (shared_buffers, work_mem, maintenance_work_mem, wal and checkpoint settings, etc.) are you using autovacuum ? all tables are vacuumed and analyzed regularly ? How big are they ? Do they and indexes fit in RAM ? any particular queries that running and might be related (explain analyze results of them would be useful) disk configuration Other processes on this box ? # of connections to it (I've seen this alone push servers over the edge) HTH, Greg Williamson DBA GlobeXplorer LLC -----Original Message----- From: pgsql-performance-owner@xxxxxxxxxxxxxx on behalf of creimer@xxxxxxxxxxxxxx Sent: Fri 11/3/2006 2:32 AM To: pgsql-performance@xxxxxxxxxxxxxx Cc: Subject: [PERFORM] Context switch storm Hi, We've migrated one of our servers from pg 7.4 to 8.1 and from times to times (4 hours) the server start doing a lot of context switching and all transactions become very slow. The average context switching for this server as vmstat shows is 1 but when the problem occurs it goes to 250000. CPU and memory usage are ok. What is producing this context switching storms? It is a box with 16GB RAM and 4 XEON processors running RedHat Enterprise Linux AS. Should I disable Hyperthreading? Thank you in advance! Reimer ------------------------------------------------------- Click link below if it is SPAM gsw@xxxxxxxxxxxxxxxx "https://mailscanner.globexplorer.com/dspam/dspam.cgi?signatureID=454b34ac206028992556831&user=gsw@xxxxxxxxxxxxxxxx&retrain=spam&template=history&history_page=1"; !DSPAM:454b34ac206028992556831! -------------------------------------------------------
