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    SubjectRe: [PATCH 1/2] lib: Provide generic atomic64_t implementation
    Avi Kivity writes:

    > An alternative implementation using 64-bit cmpxchg will recover most of
    > the costs of hashed spinlocks. I assume most serious 32-bit
    > architectures have them?

    Have a 64-bit cmpxchg, you mean? x86 is the only one I know of, and
    it already has an atomic64_t implementation using cmpxchg8b (or
    whatever it's called).

    My thinking is that the 32-bit non-x86 architectures will be mostly
    UP, so the overhead is just an interrupt enable/restore. Those that
    are SMP I would expect to be small SMP -- mostly just 2 cpus and maybe
    a few 4-way systems.

    Paul.


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