[PATCH 4/4] kvmppc: convert wrteei to wrtee as kvm guest optimization

[Josh Boyer]

On Wed, 20 Aug 2008 14:06:51 -0500
Hollis Blanchard <hollisb at us.ibm.com> wrote:  
> > > > To be honest I unfortunately don't know how big the impact for 
> > > > non-virtualized systems is. I would like to test it, but without 
> > > > hardware performance counters on the core I have I'm not sure (yet)
> > > > how 
> > > > to measure that in a good way - any suggestion welcome.
> > > 
> > > I don't see why we need performance counters. Can't we just compare any
> > > bare metal benchmark results with the patch both applied and not?
> > 
> > Do you know of one that causes a large amount of
> > local_irq_{disable,enable}s to be called?
> 
> I think *every* workload causes a large number of
> local_irq_{disable,enable} calls... :)

Well, sure.  I was just going for "test the change as specifically as
possible."  One could write a module that did X number of
disable/enable pairs and reported the timebase at start and end to
compare.  X could even be a module parameter.  Just to try and
eliminate noise or whatever from the testing.

/me shrugs.

josh