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    SubjectRe: [PATCH 3/3] readahead: scale max readahead size depending on memory size
    On Sun, 22 July 2007 18:44:03 +0200, Jens Axboe wrote:
    > >
    > > > I agree with the low point of 128k.
    > >
    > > Perhaps that should be enforced then, because currently a system with
    > > <64M will get less.
    >
    > I think it should remain the low point.

    I believe this whole thing is fundamentally flawed. The perfect
    readahead size depends on the device in question. If we set a single
    system-wide value depending on memory size, it may easily be too small
    and too large at the same time. Think hard disk and SSD.

    It may make sense to have a _maximum_ readahead size which depends on
    memory size. But the preferred size (if there is enough RAM) should
    depend solely on the device, possibly as a function of the
    bandwidth * read latency product.

    Jörn

    --
    Joern's library part 12:
    http://physics.nist.gov/cuu/Units/binary.html
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