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    SubjectRe: [PATCH] Add memcpy_cachebypass, a copy routine that tries to keep cache pressure down
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    From: Bryan O'Sullivan <bos@serpentine.com>
    Date: Tue, 11 Jul 2006 13:50:55 -0700

    > This copy routine is memcpy-compatible, but on some architectures will use
    > cache-bypassing loads to avoid bringing the source data into the cache.
    >
    > One case where this is useful is when a device issues a DMA to a memory
    > region, and the CPU must copy the DMAed data elsewhere before doing any
    > work with it. Since the source data is read-once, write-never from the
    > CPU's perspective, caching those addresses can only evict potentially
    > useful data.
    >
    > We provide an x86_64 implementation that uses SSE non-temporal loads,
    > and a generic version that falls back to plain memcpy.
    >
    > Implementors for other arches should not use cache-bypassing stores to
    > the destination, as in most cases, the destination is accessed almost
    > immediately after a copy finishes.
    >
    > Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
    > Signed-off-by: Bryan O'Sullivan <bryan.osullivan@qlogic.com>

    Please don't use a weak attribute, and instead use the same
    "__HAVE_ARCH_FOO" cpp test scheme used for the other string
    operations to allow a platform to override the default
    implementation in lib/string.x
    -
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