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    SubjectRe: Strange interrupt behaviour
    On Sun, Jul 12, 1998 at 07:35:25AM +0200, Linus Torvalds wrote:
    > So the sligtly uglier version of this is to do all page allocations as 8kB
    > chunks, and then the memory management layer has its own "sub-buddy" to
    > split a 8kB page into two hardware pages. The sparc already does something
    > like this for some of its page table pages, which are partial pages rather
    > than a full page like on a normal architecture. It wouldn't be too painful
    > to do this generically.

    The disadvantage of that is that all the kernel parts using __get_fee_page()
    [especially select() comes to mind which uses 2 pages per waiting process]
    would waste an awful lot of memory.

    > However, I'd prefer to still try out some other ways of handling this. For
    > example, "__get_free_pages()" currently only re-tries once. It shouldn't
    > be hard to make it re-try a few more times, and it might well be enough to
    > make the problem go away.

    Or it might not. This is just "randomly throwing pages away, maybe we have
    luck". Does not look like a good reliable strategy.

    > 2.1.x is not going to be usable on 4MB machines. I didn't even have to
    > change the kernel for that - the distributions have made that abundantly
    > clear anyway. It may be that we will simply say that "hey, if you have a
    > 486-8MB, then 2.0.x works better, and the new features of 2.1.x aren't
    > worth it for you".

    This is correct (I said 8MB :), but I would be worried if it was not usable
    on a 16MB machine.

    >
    > One of the reasons I disliked Minix back when I used it was that it was
    > designed for a machine that was no longer current. I want new versions of
    > Linux to be optimized for new hardware, and I also think that it should be
    > acceptable to
    But that's no excuse to waste memory except for very good reasons. The 5%
    rule applies (5% here, 5% there, the result is something as bloated as
    Solaris or NT)


    -Andi


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