Todd Lipcon has submitted this change and it was merged.
Change subject: cfile_set: avoid Status allocation for row not found
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cfile_set: avoid Status allocation for row not found
We expect Bloom Filter lookups to typically return "row not found". The
code currently indicates this using a Status::NotFound(). However,
constructing such a status involves an alloc/free pair, which is
relatively expensive to do millions of times per second for this common
case.
In a profile of tcph_real_world, the tserver spends a good chunk of its
CPU in these code paths, especially now that our alloc/free contain
heavier instrumentation for memory accounting.
This changes to using a boost::optional<rowid_t> out-parameter for the
common case instead.
Benchmarked with tpch_real_world SF300 as in change ID
I8b7e703c82ac14fbce3a699bdf6a2f0fb4ed93a1:
Before After
Mem rejections 62,790 75,318 (1.20x more)
Wall time 2490s 2185s (1.14x faster)
Server CPU 72,873s 61,879s (1.18x faster)
The increased mem rejections makes sense, since we're now able to insert
a bit faster while maintenance operations stayed the same speed. The CPU
improvements are due to this optimization, and the wall improvement is a
result of the CPU improvement.
Change-Id: I3056aaaf0eec6b7deebcd1f206cb551b75996927
Reviewed-on: http://gerrit.cloudera.org:8080/6804
Tested-by: Kudu Jenkins
Reviewed-by: Adar Dembo <[email protected]>
---
M src/kudu/tablet/cfile_set.cc
M src/kudu/tablet/cfile_set.h
M src/kudu/tablet/diskrowset.cc
3 files changed, 33 insertions(+), 24 deletions(-)
Approvals:
Adar Dembo: Looks good to me, approved
Kudu Jenkins: Verified
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Gerrit-MessageType: merged
Gerrit-Change-Id: I3056aaaf0eec6b7deebcd1f206cb551b75996927
Gerrit-PatchSet: 3
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Todd Lipcon <[email protected]>
Gerrit-Reviewer: Adar Dembo <[email protected]>
Gerrit-Reviewer: David Ribeiro Alves <[email protected]>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Tidy Bot
Gerrit-Reviewer: Todd Lipcon <[email protected]>
