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    Subjectpossible corrections in the docs (Re: [PATCH] [7/50] x86: expand /proc/interrupts to include missing vectors, v2)
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    * Sat, 22 Sep 2007 00:32:05 +0200 (CEST)

    []
    > Index: linux/Documentation/filesystems/proc.txt
    >===================================================================
    > --- linux.orig/Documentation/filesystems/proc.txt
    > +++ linux/Documentation/filesystems/proc.txt
    > @@ -347,7 +347,40 @@ connects the CPUs in a SMP system. This
    > the IO-APIC automatically retry the transmission, so it should not be a big
    > problem, but you should read the SMP-FAQ.
    >
    > -In this context it could be interesting to note the new irq directory in 2.4.
    > +In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
    > +/proc/interrupts to display every IRQ vector in use by the system, not
    > +just those considered 'most important'. The new vectors are:
    > +
    > + THR -- a threshold interrupt occurs when ECC memory correction is occuring
    > + at too high a frequency. Threshold interrupt machinery is often put
    > + into the ECC logic, as occasional ECC memory corrections are part of
    > + normal operation (due to random alpha particles), but sequences of
    > + ECC corrections or outright failures over some short interval usually
    > + indicate a memory chip that is about to fail. Note that not every
    > + platform has ECC threshold logic, and those that do generally require
    > + it to be explicitly turned on.

    + THR -- a threshold interrupt happens, when frequency of ECC memory
    + corrections is too high. Threshold interrupt machinery is often put
    + into the ECC hardware, and must be explicitly enabled, if so. Occasional
    + ECC memory corrections are part of the normal operation (ionizing radiation
    + background). Sequences of ECC corrections or outright failures over some
    + short interval, usually indicate a memory chip, that is about to fail
    + completely.

    (that "random alpha particles" bs, must be killed anyway)

    > + TRM -- a thermal event interrupt occurs when a temperature threshold
    > + has been exceeded for some CPU chip. This interrupt may also be generated
    > + when the temperature drops back to normal.
    > +
    > + SPU -- a spurious interrupt is some interrupt that was raised then lowered
    > + by some IO device before it could be fully processed by the APIC. Hence
    > + the APIC sees the interrupt but does not know what device it came from.
    > + For this case the APIC will generate the interrupt with a IRQ vector
    > + of 0xff.

    + SPU -- a spurious interrupt. This is an interrupt, that was raised then lowered
    + so quickly, that it was not fully processed by the APIC. Hence,
    + origin of it is unknown.
    + For this case, interrupt with a IRQ vector of 0xff will be generated.

    > + RES, CAL, TLB -- rescheduling, call and tlb flush interrupts are
    > + sent from one CPU to another per the needs of the OS. Typically,
    > + their statistics are used by kernel developers and interested users to
    > + determine the occurance of interrupt floods of the given type.

    + RES, CAL, TLB -- rescheduling, call and tlb flush interrupts,
    + produced by normal OS operation. Typically,
    + this information is used by kernel developers and interested users to
    + determine the occurance of interrupt floods of the given type.


    > +The above IRQ vectors are displayed only when relevent. For example,
    available?
    > +the threshold vector does not exist on x86_64 platforms. Others are
    > +suppressed when the system is a uniprocessor. As of this writing, only
    > +i386 and x86_64 platforms support the new IRQ vector displays.
    > +
    > +Of some interest is the introduction of the /proc/irq directory to 2.4.
    > It could be used to set IRQ to CPU affinity, this means that you can "hook" an
    > IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
    > irq subdir is one subdir for each IRQ, and one file; prof_cpu_mask
    _____
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