On Sun, 6 Oct 2024 14:16:44 GMT, Claes Redestad <redes...@openjdk.org> wrote:
> #14632 showed that coalescing loads in the `ZipUtils` utility methods could > improve performance in zip-related microbenchmarks, but the suggested PR > would increase startup overheads by early use of `ByteArrayLittleEndian` > which depends on `VarHandles`. Progress was stalled as we backed out some > related early use of `ByteArray(LittleEndian)` and started exploring merge > store optimizations in C2. > > In this PR I instead suggest using `Unsafe` directly to coalesce `short`, > `int`, and `long` reads from zip data. Even with explicit bounds checking to > ensure these utilities are _always_ safe there are significant improvements > both to lookup speed and speed of opening zip files (most if not all bounds > checks are optimized away): > > > make test TEST=micro:java.util.zip.ZipFile > > Name (size) Cnt Base Error Test > Error Unit Change > GetEntry.getEntryHit 512 15 37.999 ± 0.841 34.641 ± > 0.389 ns/op 1.10x (p = 0.000*) > GetEntry.getEntryHit 1024 15 39.557 ± 0.523 36.959 ± > 1.488 ns/op 1.07x (p = 0.000*) > GetEntry.getEntryHitUncached 512 15 69.250 ± 0.931 64.851 ± > 0.987 ns/op 1.07x (p = 0.000*) > GetEntry.getEntryHitUncached 1024 15 71.628 ± 0.307 67.927 ± > 0.714 ns/op 1.05x (p = 0.000*) > GetEntry.getEntryMiss 512 15 22.961 ± 0.336 22.825 ± > 0.188 ns/op 1.01x (p = 0.158 ) > GetEntry.getEntryMiss 1024 15 22.940 ± 0.115 23.502 ± > 0.273 ns/op 0.98x (p = 0.000*) > GetEntry.getEntryMissUncached 512 15 35.886 ± 0.429 35.598 ± > 1.296 ns/op 1.01x (p = 0.395 ) > GetEntry.getEntryMissUncached 1024 15 38.168 ± 0.911 36.141 ± > 0.356 ns/op 1.06x (p = 0.000*) > Open.openCloseZipFile 512 15 62425.563 ± 997.455 56263.401 ± > 896.892 ns/op 1.11x (p = 0.000*) > Open.openCloseZipFile 1024 15 117491.250 ± 962.928 108055.491 ± > 1595.577 ns/op 1.09x (p = 0.000*) > Open.openCloseZipFilex2 512 15 62974.575 ± 911.095 57996.388 ± > 910.929 ns/op 1.09x (p = 0.000*) > Open.openCloseZipFilex2 1024 15 119164.769 ± 1756.065 108803.468 ± > 929.483 ns/op 1.10x (p = 0.000*) > * = significant > > > This PR also address some code duplication in `ZipUtils`. > > An appealing alternative would be to implement a merge load analogue to the > merge store optimizations in C2. Such optimizations would be very welcome > since it would improve similar code ou... This pull request has now been integrated. Changeset: ffb60e55 Author: Claes Redestad <redes...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/ffb60e55cd77a92d19e1fde305f5d204b9fae429 Stats: 119 lines in 5 files changed: 18 ins; 22 del; 79 mod 8341594: Use Unsafe to coalesce reads in java.util.zip.ZipUtils Reviewed-by: lancea ------------- PR: https://git.openjdk.org/jdk/pull/21377
