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    SubjectRe: [RFC 2/2] x86_64, mm: Reinsert the absent memory
    On 06/23/2013 02:32 AM, Ingo Molnar wrote:
    >
    > * Ingo Molnar <mingo@kernel.org> wrote:
    >
    >> Yet another thing to consider would be to implement an initialization
    >> speedup of 3 orders of magnitude: initialize on the large page (2MB)
    >> grandularity and on-demand delay the initialization of the 4K granular
    >> struct pages [but still allocating them] - which I suspect are a good
    >> chunk of the overhead? That way we could initialize in 2MB steps and speed
    >> up the 2 hours bootup of 32 TB of RAM to 14 seconds...
    >>
    >> [ The cost would be one more branch in the buddy allocator, to detect
    >> not-yet-initialized 2 MB chunks as we encounter them. Acceptable I
    >> think. ]
    >
    > One advantage of this scheme would be that we could use it on pretty much
    > any box, it would provide instant boot time speedups everywhere [a couple
    > of hundred msecs on a small 4GB box - significant I think] - and would
    > spread out and parallelize initialization to later stages.
    >

    Even better if we could start at the 1 GB level, which most of these
    really huge machines will have hardware support for.

    -hpa




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