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    SubjectRe: 2.6.16-rc5-mm1 -- strange load balancing problems
    Peter Williams wrote:
    > I'm seeing some strange load balancing problems with this kernel. I
    > don't think that they're due to the smpnice patches as I've applied them
    > on a standard 2.6.15-rc5 kernel and the problem doesn't happen there.
    >
    > The problem is (as I say) quite strange and (for me) very reproducible.
    > I have two programs (aspin and gsmiley) which I use to produce CPU hard
    > spinners for testing purposes. What I'm finding is that when I start
    > several copies of aspin load balancing goes as expected but when I
    > launch several copies of gsmiley they all go to the one CPU and stick
    > there like glue. (The most obvious difference between the two programs
    > is that aspin is just a command line tool while gsmiley is an X windows
    > program that spins a simley face and reports its own assessment of the
    > percentage of CPU it's getting.) The machine that I've seen this
    > problem is a hyper threading Pentium 4 and I suspect that it may be due
    > to the SCHED_MC changes which overlap SCHED_SMT a bit.
    >
    > I'm trying to test this on a non hyper threading machine but the machine
    > has crashed (different kernel) while doing the build. I'll resume this
    > effort tomorrow but I thought that I should report the problem so that
    > others could comment.
    >
    > Peter
    > PS SCHED_MC was configured in but I'll try it without tomorrow and
    > report the results.

    Configuring SCHED_MC to "no" causes this problem to go away.

    Peter
    --
    Peter Williams pwil3058@bigpond.net.au

    "Learning, n. The kind of ignorance distinguishing the studious."
    -- Ambrose Bierce
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