On Mon, Oct 12, 2009 at 10:16:56AM +0200, Jan Kiszka wrote:
> >>> Apic is lockless. For ioapic/pic I used spinlocks initially, but Avi
> >>> prefers mutexes. Theoretically it is possible to make them lockless,
> >>> but code will be complex and eventually more slow, since more then two
> >>> atomic operation will be used on irq injection path.
> >> Well, lockless is another thing.
> >>
> >> But also converting to spinlocks would indeed add some overhead:
> >> irqsave/restore. But I wonder if this isn't worth it, at least when
> >> looking at the (supposed to be fast) device passthrough scenario which
> >> would be simpler and faster.
> >>
> > Avi's point in favor of mutex is: they are as fast as spinlocks when
> > congested and allows preemption when held.
>
> ...but require scheduler activity in case of dev-passthrough, which is
> surely playing in a different league.
>
I'd rather remove dev-passthrough completely than continue adding hack upon hack
upon hack to make is some times kinda sorta work :)
--
Gleb.
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
