Re: [dpdk-dev] [PATCH v4 3/5] hash: add fallback to software CRC32 implementation

[Yerden Zhumabekov <e_zhumabekov@sts.kz>]

19.11.2014 21:07, Neil Horman пишет:
> On Wed, Nov 19, 2014 at 05:35:51PM +0600, Yerden Zhumabekov wrote:
>> static inline uint32_t
>> crc32_sse42_u32(uint32_t data, uint32_t init_val)
>> {
>> /*··__asm__ volatile(
>> ············"crc32l %[data], %[init_val];"
>> ············: [init_val] "+r" (init_val)
>> ············: [data] "rm" (data));
>> ····return init_val;*/
>>
>> But wait, will __builtin_ia32_crc32si and __builtin_ia32_crc32di
>> functions do the trick? ICC has them?
> If builtins work on both icc and gcc, yes, that would be a solution as it
> creates non sse instructions when the target cpu doesn't support it.

Can anyone acknowledge?

>
>> What about prototyping functions and extracting their bodies to separate
>> module? Does it break anything?
>>
> That would be a variant on the asm inline idea, but yes, I think that would work
> too

No luck. Performance degrades up to 30-50 percent if extracting
functions to separate module.

-- 
Sincerely,

Yerden Zhumabekov
State Technical Service
Astana, KZ