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    SubjectRe: [rfc] Near-constant time directory index for Ext2
    Martin Mares wrote:
    > Hello!
    >
    > > True. Note too, though, that on a filesystem (which we are, after all,
    > > talking about), if you assume a large linear space you have to create a
    > > file, which means you need to multiply the cost of all random-access
    > > operations with O(log n).
    >
    > One could avoid this, but it would mean designing the whole filesystem in a
    > completely different way -- merge all directories to a single gigantic
    > hash table and use (directory ID,file name) as a key, but we were originally
    > talking about extending ext2, so such massive changes are out of question
    > and your log n access argument is right.

    A gigantic hash table has serious problems with non-locality of
    reference. Basically any regular access pattern you started with is
    destroyed. This is a problem with pageable RAM, let alone disks with
    millisecond seek times.

    -- Jamie
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