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Ubuntu 14.04 LTS 32-bit vs. 64-bit Performance

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  • #11

    PAE really really sucks.

    Originally posted by imposeren View Post
    For me it's morre interesting to see comparison of 8-16GB RAM system with PAE on 32bit vs 64 bit.
    Originally posted by pinguinpc View Post
    But PAE testing is good idea
    PAE really really sucks.

    Originally posted by Linus Torlvads;
    The biggest single reason to go 64-bit is exactly
    because of physical address space. Your virtual address
    space needs to bea multiple of the physical one:
    when you hit 1GB of RAM, 32-bit virtual memory is no longer
    acceptable. You literally do need more virtual memory than

    PAE turned that very simple fact on its head, and screwed
    things up royally. Whoever came up with the idea was
    totally incompetent, and had forgotten all the DOS HIGHMEM
    pains. There's a damn good reason why we left the 286
    behind, and started using 386's, instead of having HIGHMEM
    crap with windows into a bigger physical space.

    Repeat after me: virtual space needs to be bigger than
    physical space. Not "as big". Not "smaller". It needs to
    be bigger, by a factor of at least two, and that's
    quite frankly pushing it, and you're much better off
    having a factor of ten or more.

    Anybody who doesn't get that is a moron. End of discussion.


    So repeat after me: PAE didn't ever really fix anything.
    It was a mistake. It was just a total failure, and the
    result of hw engineers not understanding software.

    So no, PAE does not mean that you can use more than
    4GB of RAM. Even before PAE, the practical limit was around
    1GB, and PAE didn't move that post a fraction of an inch!