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    SubjectRe: 2.6.0-test9 - poor swap performance on low end machines
    On Tue, 16 Dec 2003, Roger Luethi wrote:

    > One potential problem with the benchmarks is that my test box has
    > just one bar with 256 MB RAM. The kbuild and efax tests were run with
    > mem=64M and mem=32M, respectively. If the difference between mem=32M
    > and a real 32 MB machine is significant for the benchmark,

    Could you try "echo 0 > /proc/sys/vm/lower_zone_protection" ?

    I have a feeling that the lower zone protection logic could
    be badly messing up systems in the 24-48 MB range, as well
    as systems in the 1.5-3 GB range.

    This would be because the allocation threshold for the
    lower zone would be 30% higher than the high threshold
    of the pageout code, meaning that the memory in the lower
    zone would be just sitting there, without old pages being
    recycled by the pageout code.

    In effect, your 32 MB test would have old memory in the
    lower 16 MB, without the pageout code reusing that memory
    for something more useful, reducing the amount of memory
    the system really uses well to something way lower.

    "Debugging is twice as hard as writing the code in the first place.
    Therefore, if you write the code as cleverly as possible, you are,
    by definition, not smart enough to debug it." - Brian W. Kernighan

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