RFR: 8334342: Add MergeStore JMH benchmarks [v5]

[Emanuel Peter]

On Tue, 18 Jun 2024 01:09:49 GMT, Shaojin Wen <duke at openjdk.org> wrote:

>> Shaojin Wen has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 13 additional commits since the last revision:
>> 
>>  - Merge remote-tracking branch 'upstream/master' into merge_store_bench
>>  - bug fix for `putChars4C`
>>  - bug fix for `putChars4C` and `putChars4S`
>>  - use VarHandler CHAR_L & CHAR_B
>>  - copyright
>>  - bug fix for putIntBU
>>  - add cases for `getChar` & `putChar`
>>  - code format
>>  - add `setIntRL` & `setIntRLU`
>>  - add comments
>>  - ... and 3 more: https://git.openjdk.org/jdk/compare/322c6e37...4c9b9418
>
> I re-ran the performance test based on WebRevs 04: [Full](https://webrevs.openjdk.org/?repo=jdk&pr=19734&range=04) - [Incremental](https://webrevs.openjdk.org/?repo=jdk&pr=19734&range=03-04) ([4c9b9418](https://git.openjdk.org/jdk/pull/19734/files/4c9b9418fc4a95504867b6019b3e94605917f747)) .
> 
> # 1. Cases MergeStore does not work
> @eme64 
> I found `putChars4BV` and `putChars4LV` two cases MergeStore didn't work, if support can be enhanced, it would be useful for people using VarHandle.
> 
> 
> putChars4BV
> putChars4LV
> 
> 
> I also found that the performance of the case using VarHandle is particularly good. Why? For example:
> 
> setIntBV
> setIntLV
> setLongBV
> setLongLV
> 
> 
> # 2. Performance numbers
> The names of these cases have the following B/L/V/U suffixes, which are:
> 
> B BigEndian
> L LittleEndian
> V VarHandle
> U Unsafe
> R reverseBytes
> C Unsafe.getChar & putChar
> S Unsafe.getShort & putShort
> 
> 
> ## 2.1 MacBook M1 Pro (aarch64)
> 
> Benchmark                    Mode  Cnt      Score    Error  Units
> MergeStoreBench.getCharB     avgt   15   5340.200 ?  7.038  ns/op
> MergeStoreBench.getCharBU    avgt   15   5482.163 ?  7.922  ns/op
> MergeStoreBench.getCharBV    avgt   15   5074.165 ?  6.759  ns/op
> MergeStoreBench.getCharC     avgt   15   5051.763 ?  6.552  ns/op
> MergeStoreBench.getCharL     avgt   15   5374.464 ?  9.783  ns/op
> MergeStoreBench.getCharLU    avgt   15   5487.532 ?  6.368  ns/op
> MergeStoreBench.getCharLV    avgt   15   5071.263 ?  9.717  ns/op
> MergeStoreBench.getIntB      avgt   15   6277.984 ?  6.284  ns/op
> MergeStoreBench.getIntBU     avgt   15   5232.984 ? 10.384  ns/op
> MergeStoreBench.getIntBV     avgt   15   1206.264 ?  1.193  ns/op
> MergeStoreBench.getIntL      avgt   15   6172.779 ?  1.962  ns/op
> MergeStoreBench.getIntLU     avgt   15   5157.317 ? 16.077  ns/op
> MergeStoreBench.getIntLV     avgt   15   2558.110 ?  3.402  ns/op
> MergeStoreBench.getIntRB     avgt   15   6889.916 ? 36.955  ns/op
> MergeStoreBench.getIntRBU    avgt   15   5769.950 ? 11.499  ns/op
> MergeStoreBench.getIntRL     avgt   15   6625.605 ? 10.662  ns/op
> MergeStoreBench.getIntRLU    avgt   15   5746.742 ? 11.945  ns/op
> MergeStoreBench.getIntRU     avgt   15   2544.586 ?  2.769  ns/op
> MergeStoreBench.getIntU      avgt   15   2541.119 ?  3.252  ns/op
> MergeStoreBench.getLongB     avgt   15  12098.129 ? 31.451  ns/op
> MergeStoreBench.getLongBU    avgt   15   9760.621 ? 16.427  ns/op
> MergeStoreBench.getLongBV    avgt   15   2593.635 ?  4.698  ns/op
> MergeStoreBench.getLongL     avgt   15  12031.065 ? 19.820  ns/op
> Merge...

@wenshao what is the state of this PR?

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PR Comment: https://git.openjdk.org/jdk/pull/19734#issuecomment-2247964317