Jim Apple has posted comments on this change. Change subject: IMPALA-2809: improve ByteSwap with builtin function or SSE or AVX2 ......................................................................
Patch Set 3: (8 comments) http://gerrit.cloudera.org:8080/#/c/3081/3/be/src/benchmarks/bswap-benchmark.cc File be/src/benchmarks/bswap-benchmark.cc: Line 35: Impala These names are pretty confusing. Aren't all of the benchmarked functions impala byteswaps? Line 121: vector<Decimal4Value> d4_values; What to decimals have to do with byteswapping? Line 151: inline void ByteSwapAVX2(void* dest, const void* source, int len) { It would be good to benchmark the function actually used for byteswapping, not these close approximations. That way, if the one used in production changes, re-running this benchmark will show the news results. Line 156: if (num_bytes == 4) { This is a lot of code with a lot of near-repetition and no comments. It could use refactoring and a high-level explanation of the algorithm. The name is true for the other functions below. http://gerrit.cloudera.org:8080/#/c/3081/3/be/src/util/bit-util.inline.h File be/src/util/bit-util.inline.h: Line 140: const __m128i mask = _mm_set_epi8(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, Can you lift this out of the function into a global that gets initialized on impalad start? That might get you a speedup. Line 164: const __m256i mask = _mm256_set_epi8(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, Same comment here about lifting to a global. Line 174: inline void ByteSwapAVX2(void* dest, const void* source, int len) { You can combine this with ByteSwapSSE by making 32 and ByteSwapAVX2_Unit template parameters. Line 193: } else if( CpuInfo::IsSupported(CpuInfo::SSE4_2) ){ LIKELY(CpuInfo:: .... -- To view, visit http://gerrit.cloudera.org:8080/3081 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: I392ed5a8d5683f30f161282c228c1aedd7b648c1 Gerrit-PatchSet: 3 Gerrit-Project: Impala Gerrit-Branch: cdh5-trunk Gerrit-Owner: Youwei Wang <[email protected]> Gerrit-Reviewer: Alex Behm <[email protected]> Gerrit-Reviewer: Jim Apple <[email protected]> Gerrit-Reviewer: Marcel Kornacker <[email protected]> Gerrit-Reviewer: Mostafa Mokhtar <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-Reviewer: Youwei Wang <[email protected]> Gerrit-HasComments: Yes
