Re: [V6][PATCH 4/6] x86, nmi: add in logic to handle multiple events and unknown NMIs

Don Zickus
2011-10-03T13:14:23Z

On Sun, Oct 02, 2011 at 12:07:16PM +0200, Avi Kivity wrote:
> >Right. Avi, Jeremy what was your objection that needed this optimization
> >in the first place?
> >
>
> First, iterating over all NMI sources is going to be slow, and a lot
> more so in a guest. This reduces the performance of perf.

I understand and agree. The only positive I can offer is most machines
will most likely only have two NMI handlers registered: perf and
arch_backtrace. So any slowness should be minimal. We might even be able
to code up arch_backtrace to register its NMI handler when it is called to
minimize the the number of NMI sources even more.

Cheers,
Don

>
> Second, I wanted to use NMIs as a way of waking up a vcpu sleeping
> with interrupts disabled (in the context of Jeremy's paravirt
> spinlock patches). Looks like we'll have to use paravirtualization
> for that.

>
> --
> error compiling committee.c: too many arguments to function
>