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    SubjectRe: [PATCH] improved boot time TSC synchronization
    Jamie Lokier wrote:
    > It looks like not only can you synchronise with a certain accuracy,
    > you can determine an upper bound on that accuracy (assuming the
    > underlying CPU clocks are locked).
    > Maybe that figure could be put into /proc/cpuinfo?
    > As well as being an interesting value, it may be useful for programs
    > to know the effective accuracy of `rdtsc'.
    > -- Jamie

    Hi Jamie,

    Yeah, I'd be glad to add the round-trip time to cpuinfo. I see
    this as a bogomips like metric. It tells you how quickly you
    can move cache lines from chip to chip.

    The patch currently prints the round-trip time and the max_delta.
    On a Quad P4 Xeon, I got round-trip times in the 0.7 microsecond
    range which is disappointing. The max_delta was almost always
    zero cycles meaning that the feedback loop thinks that the TSC values
    are perfectly synchronized.

    Jim Houston - Concurrent Computer Corp.
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