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    SubjectAdd a sysconf syscall
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    We ran into some problems with programs querying then number
    of processors at startup through sysconf. This calls into /proc
    from glibc, which is quite slow and scales poorly if the program
    is frequently executed. This happens with programs using
    Sleepycat DB for example.

    While there are worarounds -- like using sched_getaffinity --
    they don't have quite equivalent semantics.

    This patchkit adds a sysconf() syscall to the kernel that allows
    to get this information much faster. It only implements a subset
    of sysconf() -- all the information the kernel knows usefully
    about.

    Another advantage is that the kernel can in several cases offer
    more accurate information than glibc, which has to guess.

    The syscall is quite compat and not a significant burden.

    In addition I did a few cleanups first to export all the information
    needed by sysconf clearly from other subsystems.

    -Andi



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