Hello Dan Burkert, Adar Dembo,
I'd like you to do a code review. Please visit
http://gerrit.cloudera.org:8080/8001
to review the following change.
Change subject: block_id: use a better hash function
......................................................................
block_id: use a better hash function
In looking at LBM startup time I noticed that the insertion into the block
hashmap was taking substantially longer than advertised in various benchmarks.
That led me to think that our block ID patterns were causing high collision
rates.
Swapping out the hash function for block IDs reduced the startup time
substantially.
Tested on a host with ~11M blocks across 14 drives using 'fs check'.
Before:
I0907 13:01:46.997755 21274 fs_manager.cc:335] Time spent opening block
manager: real 114.501s user 0.000s sys 0.002s
After:
I0907 12:58:42.863929 20320 fs_manager.cc:335] Time spent opening block
manager: real 69.951s user 0.001s sys 0.001s
Change-Id: I30717955f962957d109a6403b55d59ab6c446a87
---
M src/kudu/fs/block_id.h
1 file changed, 7 insertions(+), 1 deletion(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/01/8001/1
--
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I30717955f962957d109a6403b55d59ab6c446a87
Gerrit-PatchSet: 1
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Todd Lipcon <[email protected]>
Gerrit-Reviewer: Adar Dembo <[email protected]>
Gerrit-Reviewer: Dan Burkert <[email protected]>
