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    SubjectRe: Machine's high load when HIGHMEM is enabled
    On Sun, Nov 03 2002, Brian Gerst wrote:
    > vasya vasyaev wrote:
    > >Hello,
    > >
    > >I have some strange kind of problem:
    > >When HIGHMEM-enabled kernel is used, there is too high
    > >CPU load on any task - computer get loaded high while
    > >it is doing some minor, usual jobs (load average grows
    > >significantly).
    >
    > 2.4 can only do I/O to and from lowmem. This means highmem pages have

    2.4.19 and below, 2.4.20-pre/rc can dma to/from highmem pages just fine.

    > to use bounce buffers in lowmem, and th edata is copied to/from highmem
    > which is causing the cpu load. This has been corrected in 2.5, which
    > can do I/O to any page the device can DMA from.

    I seriously doubt this is his problem, sounds like something else. For
    gzip to be disk bound (and thus bounce bound) you would need a seriously
    fast cpu. And the ssh problem cannot be explained by bouncing either.

    --
    Jens Axboe

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