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From "Jim Apple (Code Review)" <ger...@cloudera.org>
Subject [Impala-CR](cdh5-trunk) Use AVX2 operations to speedup Bloom filters by 10-100%.
Date Wed, 15 Jun 2016 03:14:46 GMT
Jim Apple has posted comments on this change.

Change subject: Use AVX2 operations to speedup Bloom filters by 10-100%.
......................................................................


Patch Set 7:

(7 comments)

http://gerrit.cloudera.org:8080/#/c/3338/7/be/src/util/bloom-filter-test.cc
File be/src/util/bloom-filter-test.cc:

PS7, Line 41: instructionshalf
> nit: missing space before 'half'
Done


http://gerrit.cloudera.org:8080/#/c/3338/7/be/src/util/bloom-filter.h
File be/src/util/bloom-filter.h:

Line 109:   // TODO: Use Bits::Log2Ceiling64(numeric_limits<BucketWord>::digits) once
we enable
> This should be enabled now, so if you feel like trying, we could just fix i
Unfortunately, it isn't constexpr yet, and it's in a Google library.


Line 176:   if (CpuInfo::IsSupported(CpuInfo::AVX2)) {
> Can you call CpuInfo::IsSupported once at Init or BloomFilter() and use a c
I could call it in the constructor, but given how cheap it is to check, do you think it will
save any cycles?

https://github.com/cloudera/Impala/blob/cdh5-trunk/be/src/util/cpu-info.h#L61


PS7, Line 218: BLOOM_HASH_CONSTANTS
> Maybe just undefine at the bottom of the header? It'll be easier to spot. O
added IMPALA_, moved undef to bottom of file


Line 244: inline bool BloomFilter::BucketFindAVX2(
> nit: could cut down on vertical whitespace in this function.
Slimmed down whitespace here and elsewhere.


PS7, Line 250: is
> nit: 'if' not 'is'
Done


Line 269:       return false;
> Don't need to fix, but I wonder if it would be more efficient to always che
It was slower last time I tried.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I6fef4f6652876f8fd7e3f0e41431702380418c98
Gerrit-PatchSet: 7
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Jim Apple <jbapple@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-Reviewer: Jim Apple <jbapple@cloudera.com>
Gerrit-Reviewer: Mostafa Mokhtar <mmokhtar@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: Yes

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