On Tue, 5 Sep 2023 15:48:21 GMT, 温绍锦 <d...@openjdk.org> wrote:
>> [PR 14578 ](https://github.com/openjdk/jdk/pull/14578) still has unresolved
>> discussions, continue to make improvements.
>>
>> # Benchmark Result
>>
>>
>> sh make/devkit/createJMHBundle.sh
>> bash configure --with-jmh=build/jmh/jars
>> make test TEST="micro:java.util.UUIDBench.toString"
>>
>>
>> ## 1.
>> [aliyun_ecs_c8i.xlarge](https://help.aliyun.com/document_detail/25378.html#c8i)
>> * cpu : intel xeon sapphire rapids (x64)
>>
>> ``` diff
>> -Benchmark (size) Mode Cnt Score Error Units (baseline)
>> -UUIDBench.toString 20000 thrpt 15 62.019 ± 0.622 ops/us
>>
>> +Benchmark (size) Mode Cnt Score Error Units
>> +UUIDBench.toString 20000 thrpt 15 82.998 ± 0.739 ops/us (+33.82%)
>>
>>
>> ## 2.
>> [aliyun_ecs_c8a.xlarge](https://help.aliyun.com/document_detail/25378.html#c8a)
>> * cpu : amd epc genoa (x64)
>>
>> ``` diff
>> -Benchmark (size) Mode Cnt Score Error Units (baseline)
>> -UUIDBench.toString 20000 thrpt 15 88.668 ± 0.672 ops/us
>>
>> +Benchmark (size) Mode Cnt Score Error Units
>> +UUIDBench.toString 20000 thrpt 15 89.229 ± 0.271 ops/us (+0.63%)
>>
>>
>>
>> ## 3.
>> [aliyun_ecs_c8y.xlarge](https://help.aliyun.com/document_detail/25378.html#c8y)
>> * cpu : aliyun yitian 710 (aarch64)
>> ``` diff
>> -Benchmark (size) Mode Cnt Score Error Units (baseline)
>> -UUIDBench.toString 20000 thrpt 15 49.382 ± 2.160 ops/us
>>
>> +Benchmark (size) Mode Cnt Score Error Units
>> +UUIDBench.toString 20000 thrpt 15 49.636 ± 1.974 ops/us (+0.51%)
>>
>>
>> ## 4. MacBookPro M1 Pro
>> ``` diff
>> -Benchmark (size) Mode Cnt Score Error Units (baseline)
>> -UUIDBench.toString 20000 thrpt 15 103.543 ± 0.963 ops/us
>>
>> +Benchmark (size) Mode Cnt Score Error Units
>> +UUIDBench.toString 20000 thrpt 15 110.976 ± 0.685 ops/us (+7.17%)
>>
>>
>> ## 5. Orange Pi 5 Plus
>>
>> ``` diff
>> -Benchmark (size) Mode Cnt Score Error Units (baseline)
>> -UUIDBench.toString 20000 thrpt 15 33.532 ± 0.396 ops/us
>>
>> +Benchmark (size) Mode Cnt Score Error Units (PR)
>> +UUIDBench.toString 20000 thrpt 15 33.054 ± 0.190 ops/us (-4.42%)
>
> 温绍锦 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 14 additional commits since the
> last revision:
>
> - Merge branch 'master' into optimization_for_uuid_to_string
> - remove redundant parentheses
> - fix java doc, big-endian -> little-endian
> - Merge branch 'master' into optimization_for_uuid_to_string
> - use ByteArrayLittleEndian
> - fix typo
> - code style
> - Explain the rationale
>
> Co-authored-by: liach <li...@users.noreply.github.com>
> - private static final Unsafe
> - revert to the previous version
> - ... and 4 more: https://git.openjdk.org/jdk/compare/b801e29e...2d36332b
src/java.base/share/classes/java/util/HexDigits.java line 54:
> 52: for (int j = 0; j < 16; j++) {
> 53: short lo = (short) ((j < 10 ? j + '0' : j - 10 + 'a') <<
> 8);
> 54: digits[(i << 4) + j] = (short) (hi | lo);
The variable naming and this `hi | lo` expression are counter-intuitive; they
should be reversed to be consistent with the little-endian bit layout.
A description of the DIGITS array layout and indexing is needed; it will help
with the comprehension of the masking and shifts in the packDigits methods.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/14745#discussion_r1318950015
