Guillaume Smet wrote:
Richard,
You should be seeing context-switching jump dramatically if it's the
"classic" multi-Xeon problem. There's a point at which it seems to just
escalate without a corresponding jump in activity.
No we don't have this problem of very high context switching in our
case even when the database is very slow. When I mean very slow, we
have pages which loads in a few seconds in the normal case (load
between 3 and 4) which takes several minutes (up to 5-10 minutes) to
be generated in the worst case (load at 4 but really bad
performances).
Very strange.
If I take a look on our cpu load graph, in one year, the cpu load was
never higher than 5 even in the worst cases...
I checked with Tom last week. Thread starts below:
http://archives.postgresql.org/pgsql-hackers/2006-02/msg01118.php
He's of the opinion that 8.1.3 will be an improvement.
Thanks for pointing me this thread, I searched in -performance not in
-hackers as the original thread was in -performance. We planned a
migration to 8.1.3 so we'll see what happen with this version.
Do you plan to test it before next tuesday? If so, I'm interested in
your results. I'll post our results here as soon as we complete the
upgrade.
The client has just bought an Opteron to run on, I'm afraid. I might try
8.1 on the Xeon but it'll just be to see what happens and that won't be
for a while.
--
Richard Huxton
Archonet Ltd
