From: Bryan O'Sullivan <[email protected]>
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 <[email protected]>
> Signed-off-by: Bryan O'Sullivan <[email protected]>
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 [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
