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From "Dan Hecht (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-5073: Use mmap() instead of malloc() for buffer pool
Date Tue, 11 Apr 2017 00:16:08 GMT
Dan Hecht has posted comments on this change.

Change subject: IMPALA-5073: Use mmap() instead of malloc() for buffer pool
......................................................................


Patch Set 7:

(4 comments)

http://gerrit.cloudera.org:8080/#/c/6474/7/be/src/runtime/bufferpool/system-allocator.cc
File be/src/runtime/bufferpool/system-allocator.cc:

Line 81:       munmap(mem, fixup);
does this path occur normally? how expensive are these 2 extra munmap()s? hmm, I guess linux
doesn't support something like MAP_ALIGNED_SUPER.


http://gerrit.cloudera.org:8080/#/c/6474/7/be/src/util/memory-metrics.h
File be/src/util/memory-metrics.h:

PS7, Line 39: in use
what does that mean? i.e .does it include buffers in the free lists and TCMalloc free lists?


PS7, Line 158:  Total amount of buffer memory currently allocated.
it's hard to tell from this comment (and naming) if this is the total allocated by clients,
amount of buffer reservation allocated (in reservation tracker terms), or the total system
memory allocated (even if in free list).


PS7, Line 159: buffer memory reserved for buffers
not sure what that means. isn't all "buffer memory" reserved for buffers?


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ifbc748f74adcbbdcfa45f3ec7df98284925acbd6
Gerrit-PatchSet: 7
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-HasComments: Yes

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