Re: [PATCH] Nick's scheduler policy v10

From: Martin J. Bligh (mbligh_at_aracnet.com)
Date: 08/31/03

  • Next message: Eric W. Biederman: "Re: [UPDATED PATCH] EFI support for ia32 kernels" 
    Date:	Sun, 31 Aug 2003 13:20:58 -0700
To: Nick Piggin <piggin@cyberone.com.au>, linux-kernel <linux-kernel@vger.kernel.org>

    > This is quite a big change from v8. Fixes a few bugs in child priority,
    > and adds a small lower bound on the amount of history that is kept. This
    > should improve "fork something" times hopefully, and stops new children
    > being able to fluctuate priority so wildly.
    >
    > Eliminates "timeslice backboost" and only uses "priority backboost". This
    > decreases scheduling latency quite nicely - I can only measure 130ms for
    > a very low priority task, with a make -j3 and wildly moving an xterm around
    > in front of a mozilla window.
    >
    > Makes a fairly fundamental change to how sleeping/running is accounted.
    > It now takes into account time on the runqueue. This hopefully will keep
    > priorities more stable under varying loads.
    >
    > Includes an upper bound on the amount of priority a task can get in one
    > sleep. Hopefully this catches freak long sleeps like a SIGSTOP or unexpected
    > swaps. This change breaks the priority calculation a little bit. I'm thinking
    > about how to fix it.
    >
    > Feedback welcome! Its against 0-test4, as usual.

    Oooh - much better.

    Kernbench: (make -j vmlinux, maximal tasks)
                                  Elapsed System User CPU
                  2.6.0-test4 45.87 116.92 571.10 1499.00
             2.6.0-test4-nick 49.37 131.31 611.15 1500.75
           2.6.0-test4-nick7a 49.48 125.95 617.71 1502.00
           2.6.0-test4-nick10 46.91 114.03 584.16 1489.25

    SDET 128 (see disclaimer)
                               Throughput Std. Dev
                  2.6.0-test4 100.0% 0.3%
             2.6.0-test4-nick 102.9% 0.3%
           2.6.0-test4-nick7a 105.1% 0.5%
           2.6.0-test4-nick10 107.7% 0.2%

    System time of kernbench is back to what it would be with virgin, or
    actually a little less. Elapsed time is still up a little bit, along
    with user time, but it's getting pretty close.

    Have you looked at Rick Lindsley's schedstat patches? I don't have a
    totally up-to-date version, but that might give us a better idea of
    what's going on wrt migrations, balancing, etc.

    I'll try to get together a broader set of benchmarks and hammer on this
    some more ...

    M.
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