Hello Adar Dembo, Kudu Jenkins,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/6908
to look at the new patch set (#2).
Change subject: KUDU-2017. Fix calculation of perf improvement for flushes
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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
---
M src/kudu/tablet/tablet_replica-test.cc
M src/kudu/tablet/tablet_replica_mm_ops.cc
2 files changed, 7 insertions(+), 6 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/08/6908/2
--
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I8bcf443db857ce172b8e83758eb73a24c4b0c6af
Gerrit-PatchSet: 2
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]>
