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    SubjectRe: page fault scalability patch V11 [0/7]: overview
    William Lee Irwin III wrote:
    > William Lee Irwin III wrote:
    >
    >>>Irrelevant. Unshare cachelines with hot mm-global ones, and the
    >>>"problem" goes away.
    >
    >
    > On Sat, Nov 20, 2004 at 02:14:33PM +1100, Nick Piggin wrote:
    >
    >>That's the idea.
    >
    >
    >
    > William Lee Irwin III wrote:
    >
    >>>This stuff is going on and on about some purist "no atomic operations
    >>>anywhere" weirdness even though killing the last atomic operation
    >>>creates problems and doesn't improve performance.
    >
    >
    > On Sat, Nov 20, 2004 at 02:14:33PM +1100, Nick Piggin wrote:
    >
    >>Huh? How is not wanting to impact single threaded performance being
    >>"purist weirdness"? Practical, I'd call it.
    >
    >
    > Empirically demonstrate the impact on single-threaded performance.
    >

    I can tell you its worse. I don't have to demonstrate anything, more
    atomic RMW ops in the page fault path is going to have an impact.

    I'm not saying we must not compromise *anywhere*, but it would
    just be nice to try to avoid making the path heavier, that's all.
    I'm not being purist when I say I'd first rather explore all other
    options before adding atomics.

    But nevermind arguing, it appears Linus' suggested method will
    be fine and *does* mean we don't have to compromise.

    >
    > On Sat, Nov 20, 2004 at 01:40:40PM +1100, Nick Piggin wrote:
    >
    >>>Why the Hell would you bother giving each cpu a separate cacheline?
    >>>The odds of bouncing significantly merely amongst the counters are not
    >>>particularly high.
    >
    >
    > On Sat, Nov 20, 2004 at 02:14:33PM +1100, Nick Piggin wrote:
    >
    >>Hmm yeah I guess wouldn't put them all on different cachelines.
    >>As you can see though, Christoph ran into a wall at 8 CPUs, so
    >>having them densly packed still might not be enough.
    >
    >
    > Please be more specific about the result, and cite the Message-Id.
    >

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