Tim Armstrong has posted comments on this change. Change subject: IMPALA-2809: Improve ByteSwap with builtin function or SSSE3 or AVX2. ......................................................................
Patch Set 36: Code-Review+1 (3 comments) http://gerrit.cloudera.org:8080/#/c/3081/36/be/src/util/bit-util-test.cc File be/src/util/bit-util-test.cc: PS36, Line 109: BytewapFunc ByteSwapFunc. http://gerrit.cloudera.org:8080/#/c/3081/36/be/src/util/bit-util.cc File be/src/util/bit-util.cc: Line 183: if (i >= 16) { This branch cannot be taken if TEMPLATE_DATA_WIDTH <= 16, right? How about: TEMPLATE_DATA_WIDTH > 16 && Line 203: if (LIKELY(len < 16)) { I think we should remove all these LIKELY() annotations unless we have benchmarks showing that they improve performance. The branch predictor should already do a good job. The advice in https://kernelnewbies.org/FAQ/LikelyUnlikely is "You should use it only in cases when the likeliest branch is very very very likely, or when the unlikeliest branch is very very very unlikely. " -- 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: 36 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
