On Wed, Nov 05, 2014 at 08:49:38PM +0100, Paolo Bonzini wrote: > > > On 05/11/2014 20:47, Paolo Bonzini wrote: > > > > > > On 05/11/2014 19:19, Marcelo Tosatti wrote: > >>>>>> + * If the vcpus have matched TSCs and host clocksource is TSC, > >>>>>> + * perform request to enable masterclock. > >>>>>> + * > >>>>>> + * If the masterclock is enabled, perform request to update > >>>>>> + * masterclock values. > >>>>>> + */ > >>>>>> + if ((vcpus_matched && gtod->clock.vclock_mode == VCLOCK_TSC) || > >>>>>> + ka->use_master_clock) > >>>> > >>>> This is not an explanation, it is a literal translation from C to > >>>> English. :) Can you also explain the why, especially for the first half > >>>> of the condition? > >>>> > >>>> Paolo > >> The comment on top of pvclock_update_vm_gtod_copy says: > >> > >> "Rely on synchronization of host TSCs and guest TSCs for monotonicity." > >> > >> Then with this patch > >> > >> "If the vcpus have matched TSCs and host clocksource is TSC" > >> > >> Is it sufficient to add > >> > >> "Masterclock requires synchronized guest TSC and host clocksource TSC" > >> to this patch? > > > > Got it now, thanks. I think I misread one "enable" as "update" in your > > comment, sorry. I'll apply v2 tomorrow. > > Slightly reworded: > > /* > * Once the masterclock is enabled, always perform request in > * order to update it. > * > * Until then, if the vcpus have matched TSCs and host clocksource > * is TSC, perform request to enable masterclock. > */ > if (ka->use_master_clock || > (vcpus_matched && gtod->clock.vclock_mode == VCLOCK_TSC)) > kvm_make_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu); > > Paolo Looks good, thanks. -- 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
