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    SubjectRe: test13-pre5
    On Thu, Dec 28, 2000 at 03:14:56PM -0800, David S. Miller wrote:
    > Date: Fri, 29 Dec 2000 00:17:21 +0100
    > From: Andi Kleen <ak@suse.de>
    >
    > On Thu, Dec 28, 2000 at 02:54:52PM -0800, David S. Miller wrote:
    > > To make things like "page - mem_map" et al. use shifts instead of
    > > expensive multiplies...
    >
    > I thought that is what ->index is for ?
    >
    > It is for the page cache identity Andi... you know, page_hash(mapping, index)...

    Oops, I confused it with the 2.0 page->map_nr, which did exactly that.

    I should have known better. Thanks for correcting this brainfart.

    > And the add/sub/shift expansion of a multiply/divide by constant even
    > in its' most optimal form is often not trivial, it is something on the
    > order of 7 instructions with waitq debugging enabled last time I
    > checked.

    Wonder if it looks better with wq debugging turned off or a compressed
    ->zone.


    -Andi
    -
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