Youwei Wang has posted comments on this change.

Change subject: IMPALA-2809: Improve ByteSwap with builtin function or SSSE3 or 
AVX2.
......................................................................


Patch Set 22:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/3081/17/be/src/util/bit-util.inline.h
File be/src/util/bit-util.inline.h:

Line 156:     11, 12, 13, 14, 15, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 
14, 15);
> static without constexpr might make it slower than just const. Can you reru
Hi Jim. 
Thanks for pointing out that. Your description is true. 
Following are some experiment setup:
Hardware: Intel Core-I5 [email protected]
Data size: byteswap 1048576 bytes.
Result:
Item: AVX2[const + static]
ByteSwap benchmark:   Function     Rate (iters/ms)
--------------------------------------------------
                          AVX2           8.224e+06

Item: AVX2[static]
--------------------------------------------------
                          AVX2            8.32e+06
                        
Item: AVX2[const]
--------------------------------------------------
                          AVX2           9.042e+06
                  
Item: AVX2[none] 
--------------------------------------------------
                          AVX2           2.507e+06

As can be seen from these data, we should remove the static and keep only the 
const modifier. Thanks.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I392ed5a8d5683f30f161282c228c1aedd7b648c1
Gerrit-PatchSet: 22
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Youwei Wang <[email protected]>
Gerrit-Reviewer: Alex Behm <[email protected]>
Gerrit-Reviewer: Jim Apple <[email protected]>
Gerrit-Reviewer: Marcel Kornacker <[email protected]>
Gerrit-Reviewer: Mostafa Mokhtar <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-Reviewer: Youwei Wang <[email protected]>
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