On Thu, 23 Jan 2025 08:33:23 GMT, Matthias Ernst <d...@openjdk.org> wrote:
>> Certain signatures for foreign function calls (e.g. HVA return by value) >> require allocation of an intermediate buffer to adapt the FFM's to the >> native stub's calling convention. In the current implementation, this buffer >> is malloced and freed on every FFM invocation, a non-negligible overhead. >> >> Sample stack trace: >> >> java.lang.Thread.State: RUNNABLE >> at jdk.internal.misc.Unsafe.allocateMemory0(java.base@25-ea/Native >> Method) >> ... >> at >> jdk.internal.foreign.abi.SharedUtils.newBoundedArena(java.base@25-ea/SharedUtils.java:386) >> at >> jdk.internal.foreign.abi.DowncallStub/0x000001f001084c00.invoke(java.base@25-ea/Unknown >> Source) >> ... >> at >> java.lang.invoke.Invokers$Holder.invokeExact_MT(java.base@25-ea/Invokers$Holder) >> >> >> To alleviate this, this PR implements a per carrier-thread stacked allocator. >> >> Performance (MBA M3): >> >> >> Before: >> Benchmark Mode Cnt Score Error Units >> CallOverheadByValue.byPtr avgt 10 3.333 ? 0.152 ns/op >> CallOverheadByValue.byValue avgt 10 33.892 ? 0.034 ns/op >> >> After: >> Benchmark Mode Cnt Score Error Units >> CallOverheadByValue.byPtr avgt 30 3.311 ? 0.034 ns/op >> CallOverheadByValue.byValue avgt 30 6.143 ? 0.053 ns/op >> >> >> `-prof gc` also shows that the new call path is fully scalar-replaced vs 160 >> byte/call before. > > Matthias Ernst has updated the pull request incrementally with four > additional commits since the last revision: > > - test deep linker stack > - Merge remote-tracking branch 'origin/mernst/cache-segments' into > mernst/cache-segments > - topOfStack > - (c) test/jdk/java/foreign/TestBufferStack.java line 28: > 26: * @modules java.base/jdk.internal.foreign.abi > 27: * @build NativeTestHelper TestBufferStack > 28: * @run testng TestBufferStack This needs to enable native access now. Suggestion: * @run testng/othervm --enable-native-access=ALL-UNNAMED TestBufferStack ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/23142#discussion_r1927340517
