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    SubjectRe: Strange IDE performance change in 2.6.1-rc1 (again)
    Paolo Ornati <ornati@lycos.it> wrote:
    >
    > I know these are only performance in sequential data reads... and real life
    > is another thing... but I think the author of the patch should be informed
    > (Ram Pai).

    There does seem to be something whacky going on with readahead against
    blockdevices. Perhaps it is related to the soft blocksize. I've never
    been able to reproduce any of this.

    Be aware that buffered reads for blockdevs are treated fairly differently
    from buffered reads for regular files: they only use lowmem and we always
    attach buffer_heads and perform I/O against them.

    No effort was made to optimise buffered blockdev reads because it is not
    very important and my main interest was in data coherency and filesystem
    metadata consistency.

    If you observe the same things reading from regular files then that is more
    important.

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