Todd Lipcon has submitted this change and it was merged. ( http://gerrit.cloudera.org:8080/15549 )
Change subject: Use popcnt instruction for Bits::Count ...................................................................... Use popcnt instruction for Bits::Count I found Bits::Count to be a noticeable contributor to profiles in my TSDB benchmarking (a couple percent, if I recall correctly). This switches to using popcnt instead of a lookup table. This is technically a new CPU requirement, since the popcnt flag is separate from the SSE4.2 flag. In practice, however, it doesn't appear that there are any SSE4.2-capable machines that aren't also capable of POPCNT. So, this shouldn't actually change our hardware requirements. Another bit of evidence here is that '-msse4.2' (which we use) in clang also enables -mpopcnt by default, so it was already possible for clang to emit popcnt instructions for its own optimizations. In any case, this instruction was introduced about 10 years ago, so even if I missed one case of a 2010-era server, it's unlikely to still be in use for Kudu. Change-Id: Iad045e8b77e7baf65c42366eea3e107900eb4a64 Reviewed-on: http://gerrit.cloudera.org:8080/15549 Reviewed-by: Bankim Bhavsar <ban...@cloudera.com> Reviewed-by: Andrew Wong <aw...@cloudera.com> Tested-by: Andrew Wong <aw...@cloudera.com> --- M src/kudu/gutil/bits.cc M src/kudu/gutil/cpu.cc M src/kudu/gutil/cpu.h M src/kudu/util/init.cc 4 files changed, 30 insertions(+), 2 deletions(-) Approvals: Bankim Bhavsar: Looks good to me, but someone else must approve Andrew Wong: Looks good to me, approved; Verified -- To view, visit http://gerrit.cloudera.org:8080/15549 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: merged Gerrit-Change-Id: Iad045e8b77e7baf65c42366eea3e107900eb4a64 Gerrit-Change-Number: 15549 Gerrit-PatchSet: 3 Gerrit-Owner: Todd Lipcon <t...@apache.org> Gerrit-Reviewer: Andrew Wong <andrew.w...@cloudera.com> Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com> Gerrit-Reviewer: Bankim Bhavsar <ban...@cloudera.com> Gerrit-Reviewer: Kudu Jenkins (120) Gerrit-Reviewer: Todd Lipcon <t...@apache.org>
