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 -- 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