Messages in this thread | | | Subject | Re: + stupid-hack-to-make-mainline-build.patch added to -mm tree | From | Thomas Gleixner <> | Date | Wed, 07 Mar 2007 01:49:04 +0100 |
| |
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
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |