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    SubjectRe: 2G memory split
    On Tue, Jan 10 2006, Jeff V. Merkey wrote:
    > Alan Cox wrote:
    > >On Maw, 2006-01-10 at 09:56 -0700, Jeff V. Merkey wrote:
    > >
    > >
    > >>RH ES uses 4:4 which is ideal and superior to this hack.
    > >>
    > >>
    > >
    > >Its a non trivial trade-off. 4/4 lets you run very large physical memory
    > >systems much more efficiently than usual but you pay a cost on syscalls
    > >and some other events when using the majority of processors. The 4/4
    > >tricks also give most emulations (eg Qemu) serious heartburn trying to
    > >emulate %cr3 reloading via mmap and other interfaces with high overhead
    > >in relative terms.
    > >
    > >Of course AMD64 kind of shot the problem in the head once and for all.
    > >
    > >
    > >
    > Yep, they sure did. Seriously, the 4:4 option should also be present
    > along with 3:1 and 2:2
    > splits. You should merge your RH work into this patch and allow both.
    > It would save me one less
    > patch to maintain off the tree.

    You can't compare the two patches, saying that 4:4 should go in because
    configurable page offsets is merged is nonsense.

    Note that I'm not advocating against 4:4 as such, I have no real
    oppinion on that. It has its uses for sure, while it comes with a cost
    for others.

    Jens Axboe

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      Last update: 2006-01-10 22:03    [W:0.020 / U:2.872 seconds]
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