Todd Lipcon has posted comments on this change. ( http://gerrit.cloudera.org:8080/13591 )
Change subject: KUDU-2846: optimize predicate evaluation for primitives ...................................................................... Patch Set 6: (4 comments) http://gerrit.cloudera.org:8080/#/c/13591/6//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/13591/6//COMMIT_MSG@8 PS6, Line 8: : This changes to an optimized unrolled-by-8 predicate evaluation for : primitive columns. > Any reason to stop at 8 vs 16 or 32? for AVX2 there aren't any parallel compare operations that can do more than 8 lanes (there are operations for 8x16, 4x32, 2x64 on a 128-bit vector register, and 8x32 in a 256-bit register). There might be clever ways to get 16x8 to work for some operations but it wasn't obvious so I didn't explore it much. OK with committing this for now and coming back to further optimize later based on whether this still shows up in any profiles? http://gerrit.cloudera.org:8080/#/c/13591/3/src/kudu/common/column_predicate-test.cc File src/kudu/common/column_predicate-test.cc: http://gerrit.cloudera.org:8080/#/c/13591/3/src/kudu/common/column_predicate-test.cc@1538 PS3, Line 1538: pred.Evaluate(b, &selvec); > Should probably check the final value of num_ret. I just had this 'num_ret' bit to try to avoid the compiler completely optimizing out the loop, but I think now that I have CycleClock::Now() calls, and given Evaluate is not defined inline, it'll already ensure that the pred.Evaluate() function actually gets called. I'll just remove it. Actually validating the result would add a fair bit of complexity to the test, considering we use random datasets. I think the AllTypesScanCorrectnessTest already has good coverage (as we saw by the wall of red tests in the first iteration here) http://gerrit.cloudera.org:8080/#/c/13591/3/src/kudu/common/column_predicate.cc File src/kudu/common/column_predicate.cc: http://gerrit.cloudera.org:8080/#/c/13591/3/src/kudu/common/column_predicate.cc@654 PS3, Line 654: // For primitives, it's safe to evaluate a predicate even if the cell is > :exploding_head: you and UBSAN both http://gerrit.cloudera.org:8080/#/c/13591/3/src/kudu/common/column_predicate.cc@686 PS3, Line 686: return n_chunks * 8; > nit: Could you doc the return value? Done -- To view, visit http://gerrit.cloudera.org:8080/13591 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I9dd062961a3cd2c892997d6aba12684e603628a1 Gerrit-Change-Number: 13591 Gerrit-PatchSet: 6 Gerrit-Owner: Todd Lipcon <t...@apache.org> Gerrit-Reviewer: Adar Dembo <a...@cloudera.com> Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com> Gerrit-Reviewer: Grant Henke <granthe...@apache.org> Gerrit-Reviewer: Kudu Jenkins (120) Gerrit-Reviewer: Tidy Bot (241) Gerrit-Reviewer: Todd Lipcon <t...@apache.org> Gerrit-Comment-Date: Thu, 13 Jun 2019 15:41:04 +0000 Gerrit-HasComments: Yes
