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    SubjectRe: [PATCH 1/3] Separate IRQ-stacks from 4K-stacks option


    Lee Revell wrote:
    > On Wed, 2004-10-20 at 11:35, Arjan van de Ven wrote:
    >
    >>On Wed, Oct 20, 2004 at 11:46:32AM -0400, Timothy Miller wrote:
    >>
    >>>The rules about how long a hard irq would be allowed to run would have
    >>>to be draconian.
    >>
    >>they already are.
    >
    >
    > The IDE I/O completion in hardirq context means that one can run for
    > almost 3ms. Apparently at OLS it was decided that the target for
    > desktop responsiveness was 1ms. So this is a real problem.

    What is happening that takes 3ms, and why can't it be broken up?

    Are you talking here about PIO? Is there a limited amount of time you
    have to do the PIO before the data goes away? It may be acceptable to
    just live with PIO being slow, since high-performance systems will all
    be using DMA anyhow.

    >
    > What exactly do you mean by "draconian"?

    In this case, I mean extremely harsh and restrictive. Usually, it means
    "excessively harsh", but in this case, I mean that in a good way. :)

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