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    SubjectRe: Performance question
    Achim,

    I'm not familiar with your driver, but there may be a scatter gather limit
    which only allows 64KB at a time.

    <>< Lance.


    Achim Leubner wrote:

    > Hello,
    >
    > I'm the maintainer of the ICP Disk Array Controller driver (gdth) and
    > I have a performance question.
    > I read a big file on an ext2 filesystem under Linux 2.2.xx with "dd"
    > with a read block size of 1 MB.
    > In the gdth scsi driver and therefore on the controller I see
    > 1. read commands with a size of <= 64 KB only
    > 2. max. 2 simultaneous read commands only
    > If the commands are splitted into 64 KB I/O's, why I don't see 16
    > simultaneous commands (64 KB * 16 = 1 MB) ?
    > Could the reason be the read ahead cache implemented in
    > mm/filemap.c ?
    > Is there any possibility to change any filesystem/kernel parameters
    > to get I/O's with greater size or to get more simultaneous I/O's ?
    >
    > Any hints are greatly appreciated.
    >
    > Regards
    > Achim
    >
    >
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