On Wednesday 30 January 2008 11:44:39 pm Avi Kivity wrote: > Balaji Rao wrote: > > But don't the architectural performance counters vary between Intel and > > AMD cpus ? AFAIK, they do. And, this would pose problems during migration > > between Intel and AMD hosts. > > The also vary between Intel hosts of different models, and likely > different AMD hosts as well. The PMU is not architectural (or, in other > words, model specific). So migration and PMU pass-through are mutually > exclusive unless you have a homogeneous server farm. > Right. I had confused myself in understanding that Architectural Performance monitoring is consistent across all processors right from P6. But infact it was introduced starting with core solo and core duo. > > I am not sure how important is it to support migration between Intel and > > AMD hosts. If it were not that important, then IMO we could go ahead with > > exposing the real PMU. Maybe we could warn users against running > > profilers in the guest if they intend it to to be Intel<->AMD migrateable > > ? > > We can give the user the option to expose only the architectural PMU > (which is quite limited) and have cross-model migration, or to expose > the full PMU and lose hardware independence.
Yes. This looks like the right thing to do.. regards, balaji rao ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
