On Fri, Feb 26, 2010 at 11:46:59AM +0100, Ingo Molnar wrote: > > * Joerg Roedel <joro@xxxxxxxxxx> wrote: > > > On Fri, Feb 26, 2010 at 11:46:34AM +0200, Avi Kivity wrote: > > > On 02/26/2010 10:42 AM, Ingo Molnar wrote: > > >> Note that the 'soft PMU' still sucks from a design POV as there's no generic > > >> hw interface to the PMU. So there would have to be a 'soft AMD' and a 'soft > > >> Intel' PMU driver at minimum. > > >> > > > > > > Right, this will severely limit migration domains to hosts of the same > > > vendor and processor generation. There is a middle ground, though, > > > Intel has recently moved to define an "architectural pmu" which is not > > > model specific. I don't know if AMD adopted it. We could offer both > > > options - native host capabilities, with a loss of compatibility, and > > > the architectural pmu, with loss of model specific counters. > > > > I only had a quick look yet on the architectural pmu from intel but it looks > > like it can be emulated for a guest on amd using existing features. > > AMD CPUs dont have enough events for that, they cannot do the 3 fixed events > in addition to the 2 generic ones. Good point. Maybe we can emulate that with some counter round-robin usage if the guest really uses all 5 counters. > Nor do you really want to standardize on KVM guests on returning > 'GenuineIntel' in CPUID, so that the various guest side OSs use the Intel PMU > drivers, right? Isn't there a cpuid bit indicating the availability of architectural perfmon? Joerg -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
