Todd Lipcon has submitted this change and it was merged. Change subject: KUDU-2017. Fix calculation of perf improvement for flushes ......................................................................
KUDU-2017. Fix calculation of perf improvement for flushes The code to calculate the MM "perf improvement score" for a flush had two bugs: (1) we calculated threshold - current_usage instead of current_usage - threshold, which resulted in a negative score. (2) we had an unsigned integer overflow, which resulted in the above negative score becoming insanely large. These two wrongs "made a right" in which we'd still trigger flushes at the flush threshold, which is why this went unnoticed for quite some time. However, the flushing behavior is more aggressive than originally intended, and we would lose the correct prioritization of flushing tablets that are farther above the threshold. This patch addresses the issue. I tested using tpch_real_world against a server configured with a 40G memory limit. I verified the 'perf improvement' just prior to a flush was the expected value (151 perf improvement listed for a tablet with 1.15G MRS and 1G flush threshold) Change-Id: I8bcf443db857ce172b8e83758eb73a24c4b0c6af Reviewed-on: http://gerrit.cloudera.org:8080/6908 Reviewed-by: Adar Dembo <[email protected]> Tested-by: Kudu Jenkins --- M src/kudu/tablet/tablet_replica-test.cc M src/kudu/tablet/tablet_replica_mm_ops.cc 2 files changed, 7 insertions(+), 6 deletions(-) Approvals: Adar Dembo: Looks good to me, approved Kudu Jenkins: Verified -- To view, visit http://gerrit.cloudera.org:8080/6908 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: merged Gerrit-Change-Id: I8bcf443db857ce172b8e83758eb73a24c4b0c6af Gerrit-PatchSet: 3 Gerrit-Project: kudu Gerrit-Branch: master Gerrit-Owner: Todd Lipcon <[email protected]> Gerrit-Reviewer: Adar Dembo <[email protected]> Gerrit-Reviewer: Dan Burkert <[email protected]> Gerrit-Reviewer: David Ribeiro Alves <[email protected]> Gerrit-Reviewer: Kudu Jenkins Gerrit-Reviewer: Tidy Bot Gerrit-Reviewer: Todd Lipcon <[email protected]>
