On Wed, 2008-08-20 at 14:53 +0200, Christian Ehrhardt wrote: > > Arnd Bergmann wrote: > > On Tuesday 19 August 2008, ehrhardt@xxxxxxxxxxxxxxxxxx wrote: > > > >> Dependent on the already existing CONFIG_KVM_GUEST config option > this patch > >> changes wrteei to wrtee allowing the hypervisor to rewrite those to > nontrapping > >> instructions. Maybe we should split the kvm guest otpimizations in > two parts > >> one for the overhead free optimizations and on for the rest that > might add > >> some complexity for non virtualized execution (like this one). > >> > >> Signed-off-by: Christian Ehrhardt <ehrhardt@xxxxxxxxxxxxxxxxxx> > >> > > > > How significant is the performance impact of this change for > non-virtualized > > systems? If it's very low, maybe you should not bother with the > #ifdef, and > > if it's noticable, you might be better off using dynamic patching > for this. > > > > Arnd <>< > > > 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? -- Hollis Blanchard IBM Linux Technology Center -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
