On Mon, Apr 16, 2012 at 10:01:29PM +0300, Michael S. Tsirkin wrote: > On Mon, Apr 16, 2012 at 08:51:16PM +0300, Gleb Natapov wrote: > > > > Only when eoi is pending. This is rare. > > > > > > This is exactly while guest handles an interrupt. > > > It's not all that rare at all: e.g. device > > > drivers cause an exit from interrupt > > > handler by doing io. > > So eoi will be coalesced with io that device driver does. Exactly what > > we want. > > It won't. While we handle interrupts eoi is still set. > So there will be a couple of tests + read from userspace > Wasted not a huge overhead but it's the principle of the thing. > Linux acks irq before calling device handler. Windows for some devices does IO to a device before acking. -- 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
