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    SubjectRe: [PATCH] i386: Selectable Frequency of the Timer Interrupt
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    Linus Torvalds <torvalds@osdl.org> writes:

    > And in short-term things, the timeval/jiffie conversion is likely to be a
    > _bigger_ issue than the crystal frequency conversion.
    >
    > So we should aim for a HZ value that makes it easy to convert to and from
    > the standard user-space interface formats. 100Hz, 250Hz and 1000Hz are all
    > good values for that reason. 864 is not.

    Probably only theoretical, and probably the hardware isn't up to it...
    But what if we have:
    - 64-bit jiffies done in hardware (a counter). 1 cycle = 1 microsecond
    or even a CPU clock cycle. Can *APIC or another HPET do that?
    - 64-bit "match timer" (i.e., a register in the counter which fires IRQ
    when it matches the counter value)
    - the CPU(s) sorting the timer list and programming "match timer" with
    software timer next to be executed. Upon firing the timer, a new "next
    to be executed" timer would be programmed into the counter's "match
    timer".

    We would have no timer ticks when nobody requested them - the CPUs would
    be allowed to sleep for, say, even 50 ms when no task is RUNNING.
    --
    Krzysztof Halasa
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