On Tue, 2013-02-26 at 17:54 +0800, Herbert Xu wrote: > On Thu, Sep 27, 2012 at 03:44:22PM -0700, Tim Chen wrote: > > This patch adds the crc_pcl function that calculates CRC32C checksum using > > the > > PCLMULQDQ instruction on processors that support this feature. This will > > provide speedup over using CRC32 instruction only. > > The usage of PCLMULQDQ necessitate the invocation of kernel_fpu_begin and > > kernel_fpu_end and incur some overhead. So the new crc_pcl function is only > > invoked for buffer size of 512 bytes or more. Larger sized > > buffers will expect to see greater speedup. This feature is best used > > coupled > > with eager_fpu which reduces the kernel_fpu_begin/end overhead. For > > buffer size of 1K the speedup is around 1.6x and for buffer size greater > > than > > 4K, the speedup is around 3x compared to original implementation in > > crc32c-intel > > module. Test was performed on Sandy Bridge based platform with constant > > frequency > > set for cpu. > > > > A white paper detailing the algorithm can be found here: > > http://download.intel.com/design/intarch/papers/323405.pdf > > > > Signed-off-by: Tim Chen <tim.c.c...@linux.intel.com>
Acked. BTW, Herbert, I've also sent you a patch a few days ago to update the link to the whitepaper on the CRC32C algorithm in the code. Wonder if you have received it. Thanks. Tim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
