Messages in this thread | | | Date | Fri, 18 Jun 2010 23:16:23 +0800 | Subject | Re: [RFC 1/3] Unified NMI delayed call mechanism | From | huang ying <> |
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On Fri, Jun 18, 2010 at 10:35 PM, Ingo Molnar <mingo@elte.hu> wrote: > > * 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.
soft_irq is a delayed mechanism for IRQ, a self interrupt can be a delayed mechanism for NMI. If we can make soft_irq NMI-safe, we can use soft_irq as a backup of self interrupt (for systems without APIC and maybe for other architectures).
Best Regards, Huang Ying
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