RFR: 8282047: Enhance StringDecode/Encode microbenchmarks [v2]
Claes Redestad
redestad at openjdk.java.net
Fri Feb 25 11:09:06 UTC 2022
On Fri, 25 Feb 2022 09:41:09 GMT, Andrew Haley <aph at openjdk.org> wrote:
>> Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:
>>
>> Brent review
>
> test/micro/org/openjdk/bench/java/lang/StringDecode.java line 72:
>
>> 70: public void setup() {
>> 71: charset = Charset.forName(charsetName);
>> 72: asciiString = LOREM.substring(0, 32).getBytes(charset);
>
> This is problematic IMO in that it's missing short strings such as "Claes". Average Java strings are about 32 bytes long AFAICR, and people writing (vectorized) ijntrinsics have a nasty habit of optimizing for long strings, to the detriment of typical-length ones.
> Whether we like it or not, people will optimize for benchmarks, so it's important that benchmark data is realistic. The shortest here is 15 bytes, as far as I can see. I'd certainly include a short string of just a few bytes so that intrinsics don't cause regressions in important cases.
All good points. I've added a number of such short variants to all(?) relevant microbenchmarks. The tests should now better cover a mix of input lengths and encodings.
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PR: https://git.openjdk.java.net/jdk/pull/7516
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