IBM x345 SMP server perfomrance collapse when running jails

[Zoran Kikic]

Hello,

my IBM server don't like jails. I did a fresh 5.2.1 install and
everything worked perfect and _fast_. I did a simple performance
test with afi0 on a 500mb directory. afi0 did the backup in 82 seconds.
After that I start 3 jails, just to compare the performance
differences - well, it's a disaster! the same backup procedure
was done in 110 seconds. I couldn't believe that and started
additional 7 jails just to verify the result and surprise: backup
test took 17 minutes but the load averages were at '9,32 8,54 7,22'!?

The jails are extensive (apache, mysql, postfix, imap...) but
that should not be problem on a smp 2 x 2.8 xeon. I run the
same jails on fbsd 5.1 and didn't notice these performance problems.

The jails were build on a 5.1 installation, but I'm running 5.2.1 now -
could that be the problem? If yes, why?? I'll try to build fresh
5.2.1 jails with fresh mysql apache etc. but it takes so much time
when the other jails are running - I can't turn them off.. :/ 

Does anybody has any hints for me?

Thanks.