On Thu, May 30, 2013 at 02:58:09PM +0200, Paolo Bonzini wrote: > Il 30/05/2013 14:34, Gleb Natapov ha scritto: > >>> > > > >>> > > Ah, we check kvm_apic_has_events() in runnable. Then yes, we will not > >>> > > lose the event. > >> > > >> > Ok, then I'd prefer to have the cmpxchg directly in the if, as in > >> > http://article.gmane.org/gmane.comp.emulators.kvm.devel/110505 > >> > > > I still do not. Both of them are tricky, mine does not coalesce events > > needlessly. > > Agreed that both are tricky, but I don't think my patch is coalescing > events. If you have > > INIT SIPI INIT SIPI > ^ ^ > INIT bit cleared here SIPI bit checked here > Not sure I understand what you are trying to say here. > my patch KVM sees apic_events = INIT | SIPI and deduces that the SIPI > bit was set by the second SIPI, not by the first. In fact the first > SIPI was cancelled by the second INIT, and thus should not be processed > at all. That is called coalesced. > > Instead, with your patch KVM will service all four events; strictly > speaking it is wrong to service the first SIPI, which is why I prefer > having the cmpxchg in the beginning. > y Why is it wrong? I do not see what are you arguing about. -- Gleb. -- 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
