[Xapian-discuss] Search performance issues and profiling/debugging

[Chris Good]

Ron Kass wrote:
> Not sure what you mean by "other VMs could well be confusing your results"
> We use XenServer on this machine, but we have only one instance (DomU), 
> and only this instance is running everything locally. So there are no 
> other VMs to confuse things, and even if there were, they have nothing 
> to do with the VM we run the test on or with the test itself.
> (Can you clarify what you mean?)

If you have multiple VMs sharing the same hardware then activity on one
will obviously affect the performance on other VMs.  Since you're running
a lone DomU other DomUs aren't going to be competing for resources but 
it's possible that something in Dom0 is getting swapped in and running.

How are you accessing your drives, is DomU accessing the raw devices or is
it mapped via virtual files from Dom0?

Is it possible to run these tests either directly from Dom0 or even better
with a non-xen kernel?

Given your current configuration of a single VM xen isn't adding anything 
so removing it would eliminate any side-effects of it.  I also suspect
that it would cure your oprofile issue.

Chris