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    SubjectRe: [PATCH v4] introduce macro spin_event_timeout()
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    On Wed, Mar 11, 2009 at 3:58 PM, Benjamin Herrenschmidt
    <benh@kernel.crashing.org> wrote:
    > On Wed, 2009-03-11 at 13:18 -0500, Timur Tabi wrote:
    >> Alan Cox wrote:
    >> >> Are you talking about the udelay() inside the loop?  If so, I agree
    >> >> that this is bad and have removed it in the PowerPC-specific version:
    >> >
    >> > The behaviour you want there is system specific - 10uS is a minimum
    >> > politeness value for x86 PCI bus for example.
    >>
    >> So we need to allow for delays between successive rights?  We can
    >> provide that with a third parameter to the macro.
    >
    > I prefer Alan's method of having the macro be followed by { and } so we
    > can add things in there. The delay between access will often be somewhat
    > platform or device specific, and some drivers might be able to do useful
    > things while spinning.
    >
    > The other big advantage of that approach is that drivers that aren't in
    > an atomic section can use msleep() and allow the kernel to schedule on
    > that processor.

    Ack! I totally agree.

    g.


    --
    Grant Likely, B.Sc., P.Eng.
    Secret Lab Technologies Ltd.
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