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    SubjectRe: [GIT PULL tip/genirq] Please pull from lost-spurious-irq
    Hello, Thomas.

    On 08/02/2010 08:52 PM, Thomas Gleixner wrote:
    >> Ooh, another reason is timer locality. If timers are shared per desc,
    >> they have much higher chance of being on the same processor. Global
    >> timers would be pretty bad in that respect.
    > That's irrelevant. If you need to poll an interrupt, then it does not
    > matter at all whether you bounce some cache lines or not.
    > In fact we have two cases:
    > 1) An interrupt needs to be polled all the time. That sucks whether
    > the poll timer bounces a few cache lines or not.
    > 2) Polling an irq for some time. Either it works again after a
    > while, so your suckage is restricted to the poll period. If not
    > see #1

    Hmm... for spurious and watch the above are true and if it were the
    above two it would definitely make more sense to use per-purpose
    global timers. The problem is w/ expect tho. It's supposed to be
    used with normal hot paths, so expect/unexpect operations better be
    low overhead and local. I'll talk more about it in the other reply.

    > And it's even less of an issue as the main users of this misfeature
    > are laptops and desktop machines, where locality is not really that
    > important. If an enterprise admin decides to ignore the fact that the
    > hardware is flaky, then he does not care about the cache line bounces
    > either.

    These problems do happen on intel chipset machines and is something
    which can be worked around with some effort. Eh, let's talk on the
    other reply.



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