On Thu, May 23, 2013 at 12:12:29PM +0300, Gleb Natapov wrote: > > To address migration scenarios to physical platforms that do not support > > iTSC, the TscSequence field is used. In the event that a guest partition > > is migrated from an iTSC capable host to a non-iTSC capable host, the > > hypervisor sets TscSequence to the special value of 0xFFFFFFFF, which > > directs the guest operating system to fall back to a different clock > > source (for example, the virtual PM timer)." > > > > Why it would not/does not work after migration? > > > Please read the whole discussion, we talked about it already. We > definitely do not want to fall back to PM timer either, we want to use > reference counter instead. Case 1) On migration of TSC page enabled Windows guest, from invariant TSC host, to non-invariant TSC host, Windows guests fallback to PMTimer and not to reference timer via MSR. This is suboptimal because pmtimer emulation is excessively slow. Is there a better option? Case 2) Reference timer (via MSR) support is interesting for the case of non invariant TSC host. -- 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
