Ralf Hildebrandt put forth on 11/6/2010 9:15 AM:
- Stan Hoeppner stan@hardwarefreak.com:
What hardware platform? (AMD/Intel/SPARC/PPC, generation/freq) Intel(R) Xeon(R) CPU L5335 @ 2.00GHz
What OS platform? Debian lenny
What compiler/version? gcc version 4.4.5 (Debian 4.4.5-2)
Hmm. My Lenny systems have 4.3.2-2. Are you maybe using Squeeze, not Lenny? I'm still using i686 systems, but I wouldn't think that would change the version of GCC that gets installed. I'm not sure if this may be playing a role in this problem or not. What kernel version are you running, stock Debian or rolled from source?
What threading library? ? how do I find out?
I was mainly asking that in case your platform was something other than x86. With Linux you should be using NPTL for threading. This shouldn't be a problem.
I'm trying to help you identify what is different on your system from other OPs that is causing 2.x to perform so badly vs 1.x. If sys is high but usr and iowait aren't, then I would think the problem is in a system library, your kernel, dovecot, or more specifically, the interaction among all three.
You're using maildir correct? What filesystem are you using?
Are you doing anything in your Dovecot config, both 1.x and 2.x, that is "unique" or non-standards maybe, compared to other OPs?
Is this a virtual machine guest or bare metal host?
What do memory and swap usage look like?
What do you see for %CPU when you watch your kernel threads in top? Is one of then eating lots of CPU time? If so, which one?
-- Stan