On Wed, 30 Apr 2025 02:05:41 GMT, Vladimir Kozlov <k...@openjdk.org> wrote:
>> [JEP 483](https://bugs.openjdk.org/browse/JDK-8315737) preserves class >> information in AOT cache which helps Java startup performance. >> >> We should also preserve adapters (i2c, c2i) to further improve performance >> of class linking where adapters are generated. >> >> Short running Java application can see several percents improvement. I got >> 6% improvement when ran `HelloWorld.java` on Linux-x64 Ice Lake CPU (2.5Ghz): >> >> >> (perf stat -r 100 java -XX:AOTCache=app.aotcache -cp hello.jar HelloWorld > >> /dev/null) 2>&1 | grep elapsed >> 0.0299401 +- 0.0000504 seconds time elapsed ( +- 0.17% ) >> >> (perf stat -r 100 java -XX:AOTCache=app.aotcache >> -XX:+UnlockDiagnosticVMOptions -XX:-AOTAdapterCaching -cp hello.jar >> HelloWorld > /dev/null) 2>&1 | grep elapsed >> 0.0318654 +- 0.0000535 seconds time elapsed ( +- 0.17% ) >> >> >> New diagnostic flags are introduced (use `-XX:+UnlockDiagnosticVMOptions` to >> unlock them): >> >> >> -XX:+AOTAdapterCaching - Enable or disable saving and restoring i2c2i >> adapters >> -XX:AOTCodeMaxSize=10*M - buffer size in bytes for AOT code caching >> -XX:+AbortVMOnAOTCodeFailure - Abort VM on the first occurrence of AOT code >> caching failure >> >> By default `AOTAdapterCaching` is `false` and enabled ergonomically when >> `-XX:AOTCache` is specified. >> This flag is ignored when `AOTCache` is not specified. >> >> To use AOT adapters follow process described in JEP 483: >> >> >> java -XX:AOTMode=record -XX:AOTConfiguration=app.aotconf -cp app.jar App >> java -XX:AOTMode=create -XX:AOTConfiguration=app.aotconf >> -XX:AOTCache=app.aot -cp app.jar >> java -XX:AOTCache=app.aot -cp app.jar App >> >> >> There are several new UL flag combinations to trace the AOT code caching >> process: >> >> >> -Xlog:aot+codecache+init -Xlog:aot+codecache+exit -Xlog:aot+codecache+stubs >> >> >> @ashu-mehra is main author of changes. He implemented adapters caching. >> I did main framework (`AOTCodeCache` class) for saving and loading AOT code. >> >> Tested tier1-6,10, which includes tests with `AOTClassLinking` enabled. Also >> Xcomp,stress and JCK. > > Vladimir Kozlov has updated the pull request incrementally with one > additional commit since the last revision: > > address Ioi's comments src/hotspot/share/code/aotCodeCache.cpp line 60: > 58: vm_exit_during_initialization("Unable to use AOT Code Cache.", > nullptr); > 59: } > 60: log_info(aot, codecache, init)("Unable to use AOT Code Cache."); Should it be a warning instead? src/hotspot/share/code/aotCodeCache.cpp line 69: > 67: vm_abort(false); > 68: } > 69: log_info(aot, codecache, exit)("Unable to create AOT Code Cache."); Same here (`log_warning`?). src/hotspot/share/code/aotCodeCache.hpp line 31: > 29: * AOT Code Cache collects code from Code Cache and corresponding metadata > 30: * during application training run. > 31: * In following "production" runs this code and data can me loaded into s/me/be/ src/hotspot/share/code/codeBlob.hpp line 208: > 206: CodeBlob* as_codeblob() const { return (CodeBlob*) this; > } > 207: AdapterBlob* as_adapter_blob() const { > assert(is_adapter_blob(), "must be adapter blob"); return (AdapterBlob*) > this; } > 208: ExceptionBlob* as_exception_blob() const { > assert(is_exception_stub(), "must be exception stub"); return > (ExceptionBlob*) this; } `ExceptionBlob` is C2-specific, but `as_exception_blob()` is unused. src/hotspot/share/code/relocInfo.hpp line 1292: > 1290: void pack_data_to(CodeSection * dest) override; > 1291: void unpack_data() override; > 1292: #if defined(AARCH64) It's unfortunate to see AArch64-specific code in shared code. But I don't see anything besides`pd_destination()` and `pd_set_destination()` declarations. Where're their bodies? src/hotspot/share/runtime/sharedRuntime.cpp line 2780: > 2778: > 2779: #ifndef PRODUCT > 2780: void > AdapterHandlerLibrary::print_adapter_handler_info(AdapterHandlerEntry* > handler, AdapterBlob* adapter_blob) { Suggestion: pass `tty` explicitly as `outputStream*` void AdapterHandlerLibrary::print_adapter_handler_info_on(outptutStream* st, AdapterHandlerEntry* handler, AdapterBlob* adapter_blob) { src/hotspot/share/runtime/sharedRuntime.cpp line 2852: > 2850: entry_offset[2] = handler->get_c2i_unverified_entry() - i2c_entry; > 2851: entry_offset[3] = handler->get_c2i_no_clinit_check_entry() - > i2c_entry; > 2852: AOTCodeCache::store_code_blob(*adapter_blob, AOTCodeEntry::Adapter, > id, name, AdapterHandlerEntry::ENTRIES_COUNT, entry_offset); What the intended behavior here when `AOTCodeCache::store_code_blob` fails? ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/24740#discussion_r2069610692 PR Review Comment: https://git.openjdk.org/jdk/pull/24740#discussion_r2069611080 PR Review Comment: https://git.openjdk.org/jdk/pull/24740#discussion_r2069563790 PR Review Comment: https://git.openjdk.org/jdk/pull/24740#discussion_r2069585108 PR Review Comment: https://git.openjdk.org/jdk/pull/24740#discussion_r2069558227 PR Review Comment: https://git.openjdk.org/jdk/pull/24740#discussion_r2069547808 PR Review Comment: https://git.openjdk.org/jdk/pull/24740#discussion_r2069619002
