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SubjectRe: [V3][PATCH 6/6] x86, nmi: print out NMI stats in /proc/interrupts
On Tue, Sep 06, 2011 at 06:39:04PM +0200, Robert Richter wrote:
> On 25.08.11 12:45:48, Don Zickus wrote:
> > This is a cheap hack to add the stats to the middle of /proc/interrupts.
> > It is more of a conversation starter than anything as I am not sure
> > the right letters and place to put this stuff.
> >
> > The benefit of these stats is a better breakdown of which list the NMIs
> > get handled in either a normal handler, unknown, or external. It also
> > list the number of unknown NMIs swallowed to help check for false
> > positives or not. Another benefit is the ability to actually see which
> > NMI handlers are currently registered in the system.
> >
> > The output of 'cat /proc/interrupts/ will look like this:
> >
> > <snip>
> > 58: 275 0 864 0 PCI-MSI-edge eth0
> > NMI: 4161 4155 158 4194 Non-maskable interrupts
> > SWA: 0 0 0 0 Unknown NMIs swallowed
> > 0: 4161 4155 158 4194 NMI PMI, arch_bt
>
> What does the "0" stand for?

Just a place holder meaning NMI0 for the normal NMIs, but as you stated
below, it is more an event counter. I wanted to use LOC for local but it
was already taken.

>
> We could easily provide a statistic for each NMI handler, which would
> be more useful.

Of course, but I wasn't sure how to print that without making
/proc/interrupts look messy. I suggested earlier to Peter that I thought
about a /proc/nmi file that could print that.

>
> The syntax of the NMI printout is not yet perfect, so before adding it
> as a new interface I would rather wait a bit to discuss this more.
>
> People also could get confused because the handled count may be
> different to nmi count. This should be documented more clearly, maybe
> as event count instead of nmi count or so.

That is why I put this patch last with a big blurb on top stating this
needs more feedback. :-) The hack hook into /proc/interrupts probably
isn't reasonable either.

Cheers,
Don

>
> -Robert
>
> > UNK: 0 0 0 0 NMI
> > EXT: 0 0 0 0 NMI
> > LOC: 12653 13304 13974 12926 Local timer interrupts
> > SPU: 0 0 0 0 Spurious interrupts
> > PMI: 6 6 5 6 Performance monitoring interrupts
> > IWI: 0 0 0 0 IRQ work interrupts
> > RES: 1839 1897 1821 1854 Rescheduling interrupts
> > CAL: 524 2714 392 331 Function call interrupts
> > TLB: 217 146 593 576 TLB shootdowns
> > TRM: 0 0 0 0 Thermal event interrupts
> > THR: 0 0 0 0 Threshold APIC interrupts
> > MCE: 0 0 0 0 Machine check exceptions
> > MCP: 1 1 1 1 Machine check polls
> > ERR: 0
> > MIS: 0
>
> --
> Advanced Micro Devices, Inc.
> Operating System Research Center
>


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