14.11.2014 6:52, Neil Horman ?????: > On Thu, Nov 13, 2014 at 06:33:14PM +0100, Thomas Monjalon wrote: >> Any comment on these patches? >> >> 2014-09-03 12:05, Yerden Zhumabekov: >>> As SSE4.2 provides CRC32 instructions with either 32 and 64 bit operands, >>> new rte_hash_crc_8byte() call assisted with _mm_crc32_u64 intrinsic may be >>> useful. >>> >>> ... <skipped> ... >> > Yeah, sorry I didn't speak up earlier. I meant to ask if the __mm_crc_u64 > intrinsic will emit software emulated versions of the sse4.2 instruction in > the > event that you build with a config that doesn't enable sse4.2? If not, then > NAK, since this will break on the default build. In that event you'll have to > modify the new function to do a runtime cpu flags check to either just use the > instruction inlined with some asm, or emulate it in software.
Hello, A quick grep on dpdk source shows that rte_hash_crc() is used in librte_hash in following context: In rte_hash.c: /* Hash function used if none is specified */ #ifdef RTE_MACHINE_CPUFLAG_SSE4_2 #include <rte_hash_crc.h> #define DEFAULT_HASH_FUNC rte_hash_crc #else #include <rte_jhash.h> #define DEFAULT_HASH_FUNC rte_jhash #endif In rte_fbk_hash.h #ifdef RTE_MACHINE_CPUFLAG_SSE4_2 #include <rte_hash_crc.h> /** Default four-byte key hash function if none is specified. */ #define RTE_FBK_HASH_FUNC_DEFAULT???????rte_hash_crc_4byte #else #include <rte_jhash.h> #define RTE_FBK_HASH_FUNC_DEFAULT???????rte_jhash_1word #endif #endif I guess it covers the cpu flags check you're talking about. -- Sincerely, Yerden Zhumabekov State Technical Service Astana, KZ
