On Tue, 2007-03-06 at 16:35 -0800, Dan Hecht wrote: > >> There is no problem for realtime uses, as the reprogramming path is > >> running with local interrupts disabled. I can see the point for paravirt > >> and I'm not opposed to change / expand the interface for that. It might > >> be done by an extra clockevents feature flag, which requests absolute > >> time instead of relative time. > >> > > > > I'm not sure how much different it makes overall. It's true that > > absolute time would be a more useful interface, but because the guest > > vcpu can be preempted at any time, we could miss the timeout > > regardless. In Xen if you set a timeout for the past you get an > > immediate interrupt; I presume the clockevent code can deal with that? > > > > That's the problem though, you won't know to set it for the past since > the expiry is relative. When the vcpu starts running again, it will set > the timer to expire X ns from now, not Xns from when the timer was > requested. Ooops. I completely forgot, that you get the absolute expiry time already in ktime_t format (nanoseconds) when dev->set_next_event() is called. dev->next_event = expires; is done right before the call. So it's already there for free. tglx _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxx https://lists.osdl.org/mailman/listinfo/virtualization
