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    SubjectRe: [PATCH 1/1] via-rhine: Fix hanging with high CPU load on low-end broads.
    From
    2011/12/28 David Miller <davem@davemloft.net>:
    > From: Stephen Hemminger <shemminger@vyatta.com>
    > Date: Wed, 28 Dec 2011 10:17:10 -0800
    >
    >> Looks like the hardware isn't really disabling interrupts correctly to support
    >> NAPI. NAPI is supposed to be friendly and under load the work should move to
    >> ksoftirqd. I suspect the IRQ management in this driver is borked.
    >> There is some stupid spin loops in the IRQ handler that happen when looking for
    >> Tx IRQ. I would run with debug set  and see if this is triggering.
    >
    > This could be simply a side effect of the fact that via-rhine only does
    > RX work in it's NAPI handler.
    >
    > If all the work (or at least both TX and RX) were moved into the NAPI
    > handler, it'd probably be easier to properly shut off all IRQs during
    > NAPI processing, and thus avoid the high CPU load in the IRQ handler
    > being seen here.
    >
    > This "shut off only some interrupts" scheme is just asking for trouble.

    I agree, it's an ugly hack :)

    Is there some way I can help with this, without having to touch the
    code? (C isn't my strong language, especially not kernel mode code) :)

    /Bjarke

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