[libvirt-users] Performance tuning questions for mail server

Wed Oct 5 18:41:05 UTC 2011

On Wed, Oct 05, 2011 at 02:28:30PM -0400, Alex wrote:
> 
> Load on the server is regularly above 20, yet the processors
> generally are idle and the host is still responsive.

That's completely normal for an email server running spamassassin,
in my experience, and has nothing to do with libvirt.  IME, the
issue is DNS lookups, which spamassassin and the RBLs it uses make
*heavy* use of.  Run a caching DNS on localhost with fairly
agressive caching (i.e. go ahead and have it ignore TTLs and keep
everything for at least 5 minutes) and I expect that you'll find
that problem being rapidly resolved.

-Robin