[PERFORM] Context switch storm

[creimer]

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 25.
 
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

Re: [PERFORM] Context switch storm

[creimer]

> If you can keep your numbers of clients down below the critical > level, > you should find the overall workload is fine. 
 

We have at about 600 connections. Is this a case to use a connection pool (pg_pool) system?
 
And why this happens only with 8.0 and 8.1 and not with the 7.4?