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    SubjectRe: [PATCH][RSDL-mm 0/7] RSDL cpu scheduler for 2.6.21-rc3-mm2
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    On Tue, 2007-03-13 at 21:06 +1100, Con Kolivas wrote:
    > On Tuesday 13 March 2007 20:39, Ingo Molnar wrote:
    > > * Mike Galbraith <efault@gmx.de> wrote:
    > > > I just retested with the encoders at nice 0, and the x/gforce combo is
    > > > terrible. [...]
    > >
    > > ok. So nice levels had nothing to do with it - it's some other
    > > regression somewhere. How does the vanilla scheduler cope with the
    > > exactly same workload? I.e. could you describe the 'delta' difference in
    > > behavior - because the delta is what we are interested in mostly, the
    > > 'absolute' behavior alone is not sufficient. Something like:
    > >
    > > - on scheduler foo, under this workload, the CPU hogs steal 70% CPU
    > > time and the resulting desktop experience is 'choppy': mouse pointer
    > > is laggy and audio skips.
    > >
    > > - on scheduler bar, under this workload, the CPU hogs are at 40%
    > > CPU time and the desktop experience is smooth.
    > >
    > > things like that - we really need to be able to see the delta.
    >
    > I only find a slowdown, no choppiness, no audio stutter (it would be extremely
    > hard to make audio stutter in this design without i/o starvation or something
    > along those lines). The number difference in cpu percentage I've already
    > given on the previous email. The graphics driver does feature in this test
    > case as well so others' mileage may vary. Mike said it was terrible.

    My first test run with lame at nice 0 was truly horrid, but has _not_
    repeated, so disregard that as an anomaly. For the most part, it is as
    you say, things just get slower with load, any load. I definitely am
    seeing lurchiness which is not present in mainline. No audio problems
    with either kernel.

    > > > [...] Funny thing though, x/gforce isn't as badly affected with a
    > > > kernel build. Any build is quite noticable, but even at -j8, the
    > > > effect doen't seem to be (very brief test warning applies) as bad as
    > > > with only the two encoders running. That seems quite odd.
    > >
    > > likewise, how does the RSDL kernel build behavior compare to the vanilla
    > > scheduler's behavior? (what happens in one that doesnt happen in the
    > > other, etc.)
    >
    > Kernel compiles seem similar till the jobs get above about 3 where rsdl gets
    > slower but still smooth. Audio is basically unaffected either way.

    It seems to be a plain linear slowdown. The lurchiness I'm experiencing
    varies in intensity, and is impossible to quantify. I see neither
    lurchiness nor slowdown in mainline through -j8.

    > Don't forget all the rest of the cases people have posted.

    Absolutely, all test results count.

    -Mike

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