On Fri, 8 Sep 2023 10:32:40 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> This PR seeks to improve formatting of hex digits using >> `java.util.HexFormat` somewhat. >> >> This is achieved getting rid of a couple of lookup tables, caching the >> result of `HexFormat.of().withUpperCase()`, and removing tiny allocation >> that happens in the `formatHex(A, byte)` method. Improvements range from >> 20-40% on throughput, and some operations allocate less: >> >> >> Name Cnt Base Error Test Error Unit >> Diff% >> HexFormatBench.appenderLower 15 1,330 ± 0,021 1,065 ± 0,067 us/op >> 19,9% (p = 0,000*) >> :gc.alloc.rate 15 11,481 ± 0,185 0,007 ± 0,000 MB/sec >> -99,9% (p = 0,000*) >> :gc.alloc.rate.norm 15 16,009 ± 0,000 0,007 ± 0,000 B/op >> -100,0% (p = 0,000*) >> :gc.count 15 3,000 0,000 counts >> :gc.time 3 2,000 ms >> HexFormatBench.appenderLowerCached 15 1,317 ± 0,013 1,065 ± 0,054 us/op >> 19,1% (p = 0,000*) >> :gc.alloc.rate 15 11,590 ± 0,111 0,007 ± 0,000 MB/sec >> -99,9% (p = 0,000*) >> :gc.alloc.rate.norm 15 16,009 ± 0,000 0,007 ± 0,000 B/op >> -100,0% (p = 0,000*) >> :gc.count 15 3,000 0,000 counts >> :gc.time 3 2,000 ms >> HexFormatBench.appenderUpper 15 1,330 ± 0,022 1,065 ± 0,036 us/op >> 19,9% (p = 0,000*) >> :gc.alloc.rate 15 34,416 ± 0,559 0,007 ± 0,000 MB/sec >> -100,0% (p = 0,000*) >> :gc.alloc.rate.norm 15 48,009 ± 0,000 0,007 ± 0,000 B/op >> -100,0% (p = 0,000*) >> :gc.count 15 0,000 0,000 counts >> HexFormatBench.appenderUpperCached 15 1,353 ± 0,009 1,033 ± 0,014 us/op >> 23,6% (p = 0,000*) >> :gc.alloc.rate 15 11,284 ± 0,074 0,007 ± 0,000 MB/sec >> -99,9% (p = 0,000*) >> :gc.alloc.rate.norm 15 16,009 ± 0,000 0,007 ± 0,000 B/op >> -100,0% (p = 0,000*) >> :gc.count 15 3,000 0,000 counts >> :gc.time 3 2,000 ms >> HexFormatBench.toHexLower 15 0,198 ± 0,001 0,119 ± 0,008 us/op >> 40,1% (p = 0,000*) >> :gc.alloc.rate 15 0,007 ± 0,000 0,007 ± 0,000 MB/sec >> -0,0% (p = 0,816 ) >> :gc.alloc.rate.norm 15 0,001 ± 0,000 0,001 ± 0,000 B/op >> -40,1% (p = 0,000*) >> :gc.... > > Claes Redestad has updated the pull request incrementally with one additional > commit since the last revision: > > Add toHexDigitsByte|Short|Int|Long microbenchmarks This non-lookup version looks fine; it won't invalidate caches when used and the code is easy to understand. Thanks for the cleanup and re-checking the performance benefits. ------------- Marked as reviewed by rriggs (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/15591#pullrequestreview-1625413399
