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    SubjectRe: [RFC] Scheduler issue 1, RT tasks ...
    On Fri, Dec 21, 2001 at 09:19:04AM -0800, Davide Libenzi wrote:
    > On Fri, 21 Dec 2001, Mike Kravetz wrote:
    > > Some time back, I asked if anyone had any RT benchmarks and got
    > > little response. Performance (latency) degradation for RT tasks
    > > while implementing new schedulers was my concern. Does anyone
    > > have ideas about how we should measure/benchmark this? My
    > > 'solution' at the time was to take a scheduler heavy benchmark
    > > like reflex, and simply make all the tasks RT. This wasn't very
    > > 'real world', but at least it did allow me to compare scheduler
    > > overhead in the RT paths of various scheduler implementations.
    > Mike, a better real world test would be to have a variable system runqueue
    > load with the wakeup of an rt task and measuring the latency of the rt
    > task under various loads.
    > This can be easily implemented with cpuhog ( that load the runqueue ) plus
    > the LatSched ( scheduler latency sampler ) that will measure the exact
    > latency in CPU cycles.

    Right! Any ideas on variable system runqueue load? Should those
    other tasks be RT or OTHER? a mix? I would suspect that we would
    want multiple RT tasks on the runqueue or at least in the system
    (otherwise why worry about global semantics?).

    However, I would feel better about this if someone had a real world
    load involving RT tasks on a SMP system. At least then we could try
    to simulate a load someone cares about.

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