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    SubjectRe: [patch] Real-Time Preemption, -RT-2.6.9-rc4-mm1-U8
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    On Thu, Oct 21, 2004 at 10:14:43PM +0200, Jens Axboe wrote:
    > On Thu, Oct 21 2004, Bill Huey wrote:
    > > A lot of things are perfectly "valid" in the Linux kernel regarding
    > > stuff like that are a bit irregular. But the preemption work about
    > > to stress these things in ways that was never designed to which is
    > > why these patches are needed. Having a clear use of various locking
    > > conventions is key to getting this system to behave in a predictable
    > > manner. Quite simply, Linux was never targetted to do this and the
    > > sloppiness is showing so it's got to be removed.
    >
    > I have to disagree, I don't think the above use is either convoluted or
    > sloppy in any way. Now that we have the completion structure, certain
    > things are surely better implemented as such. But the old use is
    > perfectly valid and logical, imho.

    You use a semaphore to protect data, a completion isn't protecting data
    but preserving a certain kind of wait ordering in the code. The
    possibility of overloading the current mutex_t for PI makes for a conceptual
    mismatch when used in this case since having a kind of priority for
    completions is a bit odd. It's better to flat out use a completion
    instead, IMO.

    bill

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