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[[!tag open_issue_gnumach]]


# IRC, freenode, #hurd, 2012-07-05

    <pinotree> braunr: wrt to mach: it seems to me it ticks every 10ms or so,
      it is true?
    <braunr> yes
    <braunr> and it's not preemptible

[[microkernel/mach/gnumach/preemption]].

    <pinotree> braunr: that means a gnumach kernel currently has a maximum
      uptime of almost 500 days
    <braunr> pinotree: what do you mean ?
    <pinotree> there's an int (or uint, i don't remember) variable that keeps
      the tick count
    <braunr> yes the tick variable should probably be a 64-bits type
    <braunr> or a struct
    <braunr> but the tick count should only be used for computation on "short"
      delays
    <braunr> and it should be safe to use it even when it overflows
    <braunr> it's not the wall clock
    <pinotree> i found that when investigating why the maximum timeout for a
      mach_msg is like INT_MAX >> 2 (or 4) or something like that, also due to
      the tick count
    <braunr> iirc, in linux, they mostly use the lower 32-bits on 32-bits
      architecture, updating the 32 upper only when necessary