Re: [PATCH v4] crypto api: add crc32 pclmulqdq implementation and wrappers for table implementation

[Alexander Boyko <alexander_boyko@xyratex.com>]

1/11/13 12:08 AM, Tim Chen пишет:
> On Thu, 2013-01-10 at 23:26 +0400, Alexander Boyko wrote:
>> 1/10/13 9:54 PM, Tim Chen пишет:
>>> On Thu, 2013-01-10 at 18:54 +0400, Alexander Boyko wrote:
>>>> From: Alexander Boyko <alexander_boyko@xyratex.com>
>>>>
>>>> This patch adds crc32 algorithms to shash crypto api. One is wrapper to
>>>> gerneric crc32_le function. Second is crc32 pclmulqdq implementation. It
>>>> use hardware provided PCLMULQDQ instruction to accelerate the CRC32 disposal.
>>>> This instruction present from Intel Westmere and AMD Bulldozer CPUs.
>>>>
>>>> For intel core i5 I got 450MB/s for table implementation and 2100MB/s 
>>>> for pclmulqdq implementation (
>>> Alexander,
>>>
>>> Wonder if you have a chance to test performance of our PCLMULQDQ
>>> implementation for crc32c that's in the current code (see
>>> crc32c-pcl-intel-asm_64.asm). The throughput will probably be comparable
>>> with your implementation.
>>>
>>> Tim
>>>
>>>
>>>
>> I have no chance to test crc32c pclmul, but I tested previous crc32c
>> implementation on crc32 instruction, the speed was about 2500 MB/s. So,
>> I think, the newest version should be faster.
> It will be troublesome to maintain two separate versions of PCLMUL
> crc32c code.  So we should find out if there's performance benefit of
> your PCLMUL code over the one in the codebase.  Testing should be
> straight forward by enabling the CRYPTO_CRC32C_INTEL option in kernel
> and inserting the crc32c-intel module.   
>
> You may also want to add check in your glue code for support of the
> PCLMUL feature before calling the pclmul version.  You probably also
> don't want to use this feature if the data size is small, as
> kernel_fpu_begin and kernel_fpu_end takes significant time.  In that
> case, using the crc32c hw instructions in a loop is faster (see
> crc32c-intel_glue.c).
>
> Tim
>
Sorry, may be I was miss understood, but I am trying to add CRC32
pclmul, not CRC32C. They use different polynomial.