[Xen-users] Re: Java non-performant in a domU?

Matthew Palmer
Mon, 05 Jun 2006 13:07:39 -0000

On Mon, Jun 05, 2006 at 12:14:55AM -0500, Javier Guerra
wrote:
> On Sunday 04 June 2006 10:53 pm, Matthew Palmer wrote:
> > That''s the crazy thing -- we''ve been monitoring
everything we can, and we
> > can''t find any anomalous bottlenecks.  The application is
naturally CPU
>
> just a wild guess, but on a heavily multithreaded and multiprocessor system
> like yours, its quite possible that a given JVM could use a non-optimal
> strategy on a Xen system.  I think it''s important to test
different JVM''s,
> and different ''bitness'' of them (64bit vs. 32bit). Since
32bit x86 is _SO_
> register-starved, and Xen interferes with the infamous TLS trick, you
should
> try to use a 64bit clean system.  since you already stated that your
software
> can''t run on a 64bit JVM, maybe you could get some insight by
running a
> benchmark with similar threading and processor requirements, on all
> combinations of 32bit, 64bit, Xen and non-Xen.

Hmm.  You''ve given me some more ideas for benchmarking; I''ll
try out some
different combos (the different JVM idea is a particularly good one) and
report back to the list.

Thanks a lot for your help,