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    SubjectRe: Mmap device performance
    Date
    > > the degradation must be happening somewhere in the kernel layers. I'm
    > > currently mapping the region shared with read/write access.
    >
    > Oh, it also looks like mmap from /dev/mem disables caching. That's
    > gotta hurt...

    PCI memory access is uncached - it is meant to be, but for the P6 theres
    a sort of "vaguely cached writes" mode called write-gathering that generates
    burst writes.


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