Re: [PATCH 0/6] xen,xend,tools: NUMA support for Xen

[Ryan Harper <ryanh@us.ibm.com>]

* Keir Fraser <Keir.Fraser@cl.cam.ac.uk> [2006-07-11 10:59]:
> 
> On 11 Jul 2006, at 16:35, Ryan Harper wrote:
> 
> >Reposting the latest patches, no significant changes since May when I
> >last received feedback.  I've done some simple overhead and performance
> >numbers for these patches.
> >
> >Measuring NUMA allocator patch overhead via balloon driver and DOM0
> >involved starting DOM0 with all memory (4G) and ballooning down (256M)
> >as a starting point, [1]tracking the time it takes to balloon back up
> >to full memory.  The test was done with and without NUMA patches.
> 
> What sort of box are these numbers taken from? If it's not a NUMA 
> system then the slowdowns are rather poor. We're particularly 
> interested in not slowing down non-NUMA and small-NUMA (e.g., AMD K8) 
> x86 systems. They are what we really want to see measurements from.

The measurements are taken from a two-way Operton 248 (2.1Ghz) ,
small-NUMA.  I agree that there is significant overhead, however, we
aren't talking about fast path here; correct me if I'm wrong.   We
are only adding overhead to during domain startup.  The end result
being we pay for local memory allocation at creation time while
benefiting from local memory access for the lifetime of the domain.

I'm going to gather some oprofile data to see if I missed something
obvious, but in general I think that having local memory is of greater
benefit for the lifetime of a domain than the cost we incur during its
creation.

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@us.ibm.com