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    SubjectRe: sched_setaffinity usability


    On Thu, 18 Mar 2004, Christoph Hellwig wrote:
    >
    > Like, umm, the long overdue sysconf()? For the time beeing a sysctl might
    > be the easiest thing..

    "sysconf" has not been "long-overdue". It's just that glibc hasn't (after
    years of pleading) just fixed it.

    sysconf() MUST NOT be done in kernel space. A lot of the sysconf() options
    are pure user space stuff that the kernel has no idea about. Take a quick
    look at some of those things, and realize that there are things like
    "_SC_EXPR_NEST_MAX" etc that are _most_ of the values. And the kernel is
    simply not involved in any of this.

    So I will tell this one more time (and I bet I'll have to repeat myself
    again in a year or two, and I bet I'll be ignored then too).

    sysconf() is a user-level implementation issue, and so is something like
    "number of CPU's". Damn, the simplest way to do it is as a environment
    variable, for christ sake! Just make a magic environment variable called
    __SC_ARRAY, and make it be some kind of binary encoding if you worry about
    performance.

    Or make a "/etc/sysconf/array" file, and just map it and look up the
    values there.

    Please don't raise this issue again.

    Linus
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