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    SubjectRe: [RFC] Generic deferred file writing


    On Sun, 31 Dec 2000, Alexander Viro wrote:
    >
    > On Sun, 31 Dec 2000, Linus Torvalds wrote:
    >
    > > The other thing is that one of the common cases for writing is consecutive
    > > writing to the end of the file. Now, you figure it out: if get_block()
    > > really is a bottle-neck, why not cache the last tree lookup? You'd get a
    > > 99% hitrate for that common case.
    >
    > Because it is not a bottleneck. The _real_ bottleneck is in ext2_new_block().
    > Try to profile it and you'll see.
    >
    > We could diddle with ext2_get_block(). No arguments. But the real source of
    > PITA is balloc.c, not inode.c. Look at the group descriptor cache code and
    > weep. That, and bitmaps handling.

    I'm not surprised. Just doign pre-allocation 32 blocks at a time would
    probably help. But that code really should be re-written, I think.

    Linus

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