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    SubjectRE: [PATCH] prctl: return MCE process flags through pointer
    Earlier today, Andrew Morton <akpm@linux-foundation.org> wrote:
    >>
    >> >Why are task_struct.timer_slack_ns and
    >> >task_struct.default_timer_slack_ns unsigned long, btw? AFACIT we could
    >> >make them unsigned ints.
    >>
    >> Timer slack is not a Boolean or enum, and we want the greatest range
    >possible. (Actually, I'd like to talk Arjan into using the same time
    >structure as select(), but that's another discussion.) Internally hrtimer
    >uses unsigned long. I know long and unsigned long are the same on some
    >architectures, but let's not introduce an unnatural restriction -- recall
    >that arg2 is unsigned long.
    >
    >Using unsigned ints will reduce the size of the task_struct.
    >
    >Is there any conceivable case for a timer_slack which exceeds four
    >seconds? If so, what is it, and if so, why this:
    >
    >#define MAX_SLACK (100 * NSEC_PER_MSEC)
    >
    >

    WRT to times longer than 4.2 sec -- So far my works suggests there is a good case, but it's moot because that is all I get with unsigned long on my platform. (Both int and long are 32-bit for me; x86)

    WRT MAX_SLACK, select() always imposes a little slack (for non-real-time threads). The name MAX_SLACK is not actually the absolute maximum, it is only the maximum that the kernel will impose by default.



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