[kudu-CR] Add more trace counters and timings

["Todd Lipcon (Code Review)" <ge...@cloudera.org>]

Todd Lipcon has posted comments on this change.

Change subject: Add more trace counters and timings
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Patch Set 1:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/7819/1/src/kudu/util/env_posix.cc
File src/kudu/util/env_posix.cc:

Line 764:   virtual Status Read(uint64_t offset, Slice* result) const OVERRIDE {
> Yeah but you don't like having traces at multiple levels? What if we have h
I think my fear is that it becomes hard to know if the traces are additive or not. eg if it says "rwfile_read_time = 1sec" and "lbm_read_time = 1sec" should you expect those two add up together to a total of 2sec in the overall request latency?

I don't have a particularly good general solution to this problem, though, aside from actually capturing these things on some kind of stack, but then performance of capturing/tracking becomes a concern. Perhaps we could maintain some kind of context "call stack" of limited/fixed depth so that these things end up netting out as counters like "cfile_write.lbm_write.rwfile_write_us"?


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ie99bc9e06be682e1595745f154b7dded3903bd6e
Gerrit-PatchSet: 1
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Todd Lipcon <to...@apache.org>
Gerrit-Reviewer: Adar Dembo <ad...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Tidy Bot
Gerrit-Reviewer: Todd Lipcon <to...@apache.org>
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