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    SubjectRe: test13-pre5
       Date: Fri, 29 Dec 2000 00:17:21 +0100
    From: Andi Kleen <>

    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)...

    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

    David S. Miller
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