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From "Dan Hecht (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-5229: huge page-backed buffers with TCMalloc
Date Thu, 20 Apr 2017 03:05:13 GMT
Dan Hecht has posted comments on this change.

Change subject: IMPALA-5229: huge page-backed buffers with TCMalloc
......................................................................


Patch Set 2:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/6687/2/be/src/runtime/bufferpool/system-allocator.cc
File be/src/runtime/bufferpool/system-allocator.cc:

Line 50:   // Free() assumes that aggressive decommit is enabled for TCMalloc.
> I believe MADV_NOHUGEPAGE just prevents future merging into huge pages and 
Hmm, seems strange the kernel doesn't break the huge page automatically when needed. But I
guess it's possible that it doesn't.

So, is what you're saying that we need aggressive decomit so that the entire mapping is unmapped
immediately before it's carved up by tc-malloc (and then potentially decommitted in smaller
pieces)?


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Gerrit-MessageType: comment
Gerrit-Change-Id: If84b46a46efed9aee6af41b5f10bf3f4b15889b8
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: Yes

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