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    SubjectRe: [RFC][PATCH] Make MAX_RT_PRIO and MAX_USER_RT_PRIO configurable
    Esben Nielsen wrote:
    > On Wed, 27 Jul 2005, Ingo Molnar wrote:
    >
    >
    >>* Steven Rostedt <rostedt@goodmis.org> wrote:
    >>
    >>
    >>>Perfectly understood. I've had two customers ask me to increase the
    >>>priorities for them, but those where custom kernels, and a config
    >>>option wasn't necessary. But since I've had customers asking, I
    >>>thought that this might be something that others want. But I deal
    >>>with a niche market, and what my customers want might not be what
    >>>everyone wants. (hence the RFC in the subject).
    >>>
    >>>So if there are others out there that would prefer to change their
    >>>priority ranges, speak now otherwise this patch will go by the waste
    >>>side.
    >>
    >>i'm not excluding that this will become necessary in the future. We
    >>should also add the safety check to sched.h - all i'm suggesting is to
    >>not make it a .config option just now, because that tends to be fiddled
    >>with.
    >>
    >
    > Isn't there a way to mark it "warning! warning! dangerous!" ?
    >
    > Anyway: I think 100 RT priorities is way overkill - and slowing things
    > down by making the scheduler checking more empty slots in the runqueue.
    > Default ought to be 10. In practise it will be very hard to have
    > a task at the lower RT priority behaving real-time with 99 higher
    > priority tasks around. I find it hard to believe that somebody has an RT
    > app needing more than 10 priorities and can't do with RR or FIFO
    > scheduling within a fewer number of prorities.
    >
    > Esben
    >

    Actually, is it really that slow to search a bitmap for a slot that
    needs processing? I work on real-time test stands which are less of an
    embedded system and more of a real Unix system that require determinism.
    It is very nice in some cases to have more than 10 RT priorities to work
    with.

    --
    kr
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