On Sat, 1 Jul 2023 14:12:05 GMT, 温绍锦 <d...@openjdk.org> wrote:
>> Optimization for:
>> Integer.toString
>> Long.toString
>> StringBuilder#append(int)
>>
>> # Benchmark Result
>>
>>
>> sh make/devkit/createJMHBundle.sh
>> bash configure --with-jmh=build/jmh/jars
>> make test TEST="micro:java.lang.Integers.toString*"
>> make test TEST="micro:java.lang.Longs.toString*"
>> make test TEST="micro:java.lang.StringBuilders.toStringCharWithInt8"
>>
>>
>> ## 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)
>> -Integers.toStringBig 500 avgt 15 6.825 ± 0.023 us/op
>> -Integers.toStringSmall 500 avgt 15 4.823 ± 0.023 us/op
>> -Integers.toStringTiny 500 avgt 15 3.878 ± 0.101 us/op
>>
>> +Benchmark (size) Mode Cnt Score Error Units (PR Update
>> 04 f4aa1989)
>> +Integers.toStringBig 500 avgt 15 6.002 ± 0.054 us/op (+13.71%)
>> +Integers.toStringSmall 500 avgt 15 4.025 ± 0.020 us/op (+19.82%)
>> +Integers.toStringTiny 500 avgt 15 3.874 ± 0.067 us/op (+0.10%)
>>
>> -Benchmark (size) Mode Cnt Score Error Units (baseline)
>> -Longs.toStringBig 500 avgt 15 9.224 ± 0.021 us/op
>> -Longs.toStringSmall 500 avgt 15 4.621 ± 0.087 us/op
>>
>> +Benchmark (size) Mode Cnt Score Error Units (PR Update 04
>> f4aa1989)
>> +Longs.toStringBig 500 avgt 15 7.483 ± 0.018 us/op (+23.26%)
>> +Longs.toStringSmall 500 avgt 15 4.020 ± 0.016 us/op (+14.95%)
>>
>> -Benchmark Mode Cnt Score Error Units
>> (baseline)
>> -StringBuilders.toStringCharWithInt8 avgt 15 89.327 ± 0.733 ns/op
>>
>> +Benchmark Mode Cnt Score Error Units (PR
>> Update 04 f4aa1989)
>> +StringBuilders.toStringCharWithInt8 avgt 15 36.639 ± 0.422 ns/op
>> (+143.80%)
>>
>>
>>
>> ## 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)
>> -Integers.toStringBig 500 avgt 15 6.753 ± 0.007 us/op
>> -Integers.toStringSmall 500 avgt 15 4.470 ± 0.005 us/op
>> -Integers.toStringTiny 500 avgt 15 2.764 ± 0.020 us/op
>>
>> +Benchmark (size) Mode Cnt Score Error Units (PR Update
>> 04 f4aa1989)
>> +Integers.toStringBig 500 avgt 15 5.036 ± 0.005 us/op (+...
>
> 温绍锦 has updated the pull request incrementally with one additional commit
> since the last revision:
>
> use upper case for static final field
src/java.base/share/classes/java/lang/StringUTF16.java line 1540:
> 1538: if (isBigEndian()) {
> 1539: for (int i = 0; i < digits.length; i++) {
> 1540: digits[i] <<= 8;
I know this changes the char-based endian (so putInt puts the non-0 to right
bytes), what I suggest is something like:
digits[i] = Integer.reverseBytes(digits[i] << 8);
And you then remove the trailing `false` (little-endian) argument to
`UNSAFE.putIntUnaligned`.
This is safe because you don't use `PACKED_DIGITS_UTF16` with bitwise
operations, unlike in UUID.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/14699#discussion_r1249091010
