Re: [RFC 1/3] Unified NMI delayed call mechanism

Don Zickus
2010-06-14T15:12:57Z

On Mon, Jun 14, 2010 at 04:44:03PM +0200, Andi Kleen wrote:
> > I think the perf event subsytem can log events in NMI context already and
> > deliver them to userspace when the NMI is done. This is why I think Ingo
> > wants MCE to be updated to sit on top of the perf event subsytem to avoid
> > re-invent everything again.
>
> perf is not solving the problem this is trying to solve.
>
> > Then again I do not know enough about the MCE stuff to understand what you
> > mean when an event comes in but you can't handle it in an NMI-safe
> > context. An example would be helpful.
>
> At least for MCE hwpoison recovery needs to sleep and you obviously cannot sleep in
> NMI like context. The way it's done is to first do a self interrupt, then do a work queue
> wakeup and finally the sleeping operations.
>
> perf does not fit into this because it has no way to process such an event
> inside the kernel.

Ah, makes sense. Thanks for the example.

Cheers,
Don