On Thu, 14 Apr 2022 11:19:04 GMT, Claes Redestad <redes...@openjdk.org> wrote:
> This patch examines and optimizes `Wrapper` lookups.
>
> First wrote a few simple microbenchmarks to verify there are actual speedups
> from using perfect hash tables in `sun.invoke.util.Wrapper` compared to
> simpler lookup mechanisms (such as if-else or switch). Turns out there _is_ a
> speed-up for the case of `char` -> `Wrapper`, but not when mapping from
> `Class<?>` -> `Wrapper`, so let's drop those. The `forPrimitiveType` case
> didn't use the `FROM_CHAR` table for some reason, which is remedied.
>
> Micros show benefits across the board for warmed up case:
>
>
> Baseline, OOTB
> Benchmark Mode Cnt Score Error Units
> Wrappers.forBasicType avgt 5 14.387 ? 0.127 ns/op
> Wrappers.forPrimitive avgt 5 38.818 ? 0.592 ns/op
> Wrappers.forPrimitiveType avgt 5 26.085 ? 2.291 ns/op
> Wrappers.forWrapper avgt 5 44.459 ? 1.635 ns/op
>
> Patch, OOTB
> Benchmark Mode Cnt Score Error Units
> Wrappers.forBasicType avgt 5 14.357 ? 0.133 ns/op
> Wrappers.forPrimitive avgt 5 23.930 ? 0.071 ns/op
> Wrappers.forPrimitiveType avgt 5 14.343 ? 0.017 ns/op
> Wrappers.forWrapper avgt 5 27.622 ? 0.022 ns/op
>
>
> For `-Xint` case (`Wrapper` use is prominent during warmup, e.g., when
> spinning up of MHs) there are decent or even great wins in all cases but
> `forPrimitiveType` - which was changed from a simple switch to use the hash
> lookup. Since the interpreter penalty is small in absolute terms and the win
> on JITed code is significant this seems like a reasonable trade-off:
>
>
> Baseline, -Xint
> Benchmark Mode Cnt Score Error Units
> Wrappers.forBasicType avgt 5 1246.144 ? 149.933 ns/op
> Wrappers.forPrimitive avgt 5 4955.297 ? 329.869 ns/op
> Wrappers.forPrimitiveType avgt 5 716.840 ? 62.568 ns/op
> Wrappers.forWrapper avgt 5 5774.700 ? 367.627 ns/op
>
> Patch, -Xint
> Benchmark Mode Cnt Score Error Units
> Wrappers.forBasicType avgt 5 1068.096 ? 101.728 ns/op
> Wrappers.forPrimitive avgt 5 1146.670 ? 59.142 ns/op
> Wrappers.forPrimitiveType avgt 5 998.037 ? 118.144 ns/op
> Wrappers.forWrapper avgt 5 3581.226 ? 20.167 ns/op
Build change looks ok.
make/test/BuildMicrobenchmark.gmk line 97:
> 95: SRC := $(MICROBENCHMARK_SRC), \
> 96: BIN := $(MICROBENCHMARK_CLASSES), \
> 97: JAVAC_FLAGS := --add-exports java.base/sun.security.util=ALL-UNNAMED
> --add-exports java.base/sun.invoke.util=ALL-UNNAMED, \
Suggestion:
JAVAC_FLAGS := --add-exports java.base/sun.security.util=ALL-UNNAMED \
--add-exports java.base/sun.invoke.util=ALL-UNNAMED, \
-------------
Marked as reviewed by erikj (Reviewer).
PR: https://git.openjdk.java.net/jdk/pull/8242
