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crypto: crc32c - Optimize CRC32C calculation with PCLMULQDQ instruction

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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.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Tim Chen 2012-09-27 15:44:22 -07:00 • committed by Herbert Xu
parent 35b80920d4
commit 6a8ce1ef39
4 changed files with 552 additions and 0 deletions
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10
crypto/Kconfig
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@ -324,9 +324,19 @@ config CRYPTO_CRC32C
by iSCSI for header and data digests and by others.
See Castagnoli93. Module will be crc32c.
config CRYPTO_CRC32C_X86_64
bool
depends on X86 && 64BIT
select CRYPTO_HASH
help
In Intel processor with SSE4.2 supported, the processor will
support CRC32C calculation using hardware accelerated CRC32
instruction optimized with PCLMULQDQ instruction when available.
config CRYPTO_CRC32C_INTEL
tristate "CRC32c INTEL hardware acceleration"
depends on X86
select CRYPTO_CRC32C_X86_64 if 64BIT
select CRYPTO_HASH
help
In Intel processor with SSE4.2 supported, the processor will