Based on what other people have posted, hyperthreading seems not to be beneficial for postgres -- try searching through
thearchives 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@postgresql.org on behalf of creimer@brturbo.com.br
Sent: Fri 11/3/2006 2:32 AM
To: pgsql-performance@postgresql.org
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
contextswitching 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
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