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    SubjectRe: [rfc] aio-core for 2.5.29 (Re: async-io API registration for 2.5.29)

    On Thu, 1 Aug 2002, Chris Friesen wrote:
    > Now if we had a constant monotonic source of time--say 64-bit nanoseconds since
    > boot--this wouldn't be a problem.

    Well, we do have such a monotonic time sequence already, and that's the
    one that the kernel always uses internally.

    It's called "jiffies64".

    However, "jiffies" are not really real time, they are only a "reasonable
    abstraction thereof", and while they imply ordering ("time_after()" works
    fine inside the kernel), they do _not_ imply real time.

    In other words, there is no way to move from time -> jiffies and back.

    But we could certainly export jiffies64 as a "nanosecond-like" thing. All
    it takes is one 32x64-bit multiply. It won't be "true nanoseconds", but it
    will be a "reasonable approximation" (ie the rate may be off by several
    percentage points, since nothing is correcting for it. But the "no
    correction" is part of the _advantage_ too).


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