Messages in this thread | | | Date | Tue, 11 Jul 2006 13:57:29 -0700 (PDT) | Subject | Re: [PATCH] Add memcpy_cachebypass, a copy routine that tries to keep cache pressure down | From | David Miller <> |
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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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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