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

Ingo Molnar
2010-06-18T14:35:52Z

* huang ying <huang.ying.caritas@gmail.com> wrote:

> On Fri, Jun 18, 2010 at 8:45 PM, Ingo Molnar <mingo@elte.hu> wrote:
> >> >> [...] ??At least APEI will use NMI to report some hardware events (likely
> >> >> error) to kernel. ??So I suppose we will go to have a delayed call as an
> >> >> event handler for APEI.
> >> >
> >> > Yep, that makes sense. I wasnt arguing against the functionality itself, i
> >> > was arguing against the illogical layering that limits its utility. By
> >> > making it part of perf events it becomes a generic part of that framework
> >> > and can be used by anything that deals with events and uses that
> >> > framework.
> >>
> >> I think the the 'layering' in the patchset helps instead of 'limits' its
> >> utility. It is designed to be as general as possible, so that it can be used
> >> by both perf and other NMI users. Do you think so?
> >
> > What other NMI users do you mean? EDAC/MCE is going to go utilize events
> > as well (away from the horrible /dev/mcelog interface), the NMI watchdog
> > already did it and the perf tool obviously does as well. There's a few
> > leftovers like kcrash which isnt really event centric and i dont think it
> > needs to be converted.
>
> But why not just make it more general? It does not hurt anyone including
> perf.

Because it's not actually more generic that way - just look at the code. It's
x86 specific, plus it ties it to NMI delivery while the concept of delayed
execution has nothing to do with NMIs.

Ingo