On Fri, 17 Mar 2023 10:31:46 GMT, Serguei Spitsyn <sspit...@openjdk.org> wrote:
>> This is needed for future performance/scalability improvements in JVMTI >> support of virtual threads. >> The update includes the following: >> >> 1. Refactored the `VirtualThread` native methods: >> `notifyJvmtiMountBegin` and `notifyJvmtiMountEnd` => >> `notifyJvmtiMount` >> `notifyJvmtiUnmountBegin` and `notifyJvmtiUnmountEnd` => >> `notifyJvmtiUnmount` >> 2. Still useful implementation of old native methods is moved from `jvm.cpp` >> to `jvmtiThreadState.cpp`: >> `JVM_VirtualThreadMountStart` => `VTMS_mount_begin` >> `JVM_VirtualThreadMountEnd` => `VTMS_mount_end` >> `JVM_VirtualThreadUnmountStart` = > `VTMS_unmount_begin` >> `JVM_VirtualThreadUnmountEnd` => `VTMS_mount_end` >> 3. Intrinsified the `VirtualThread` native methods: `notifyJvmtiMount`, >> `notifyJvmtiUnmount`, `notifyJvmtiHideFrames`. >> 4. Removed the`VirtualThread` static boolean state variable >> `notifyJvmtiEvents` and its support in `javaClasses`. >> 5. Added static boolean state variable `_VTMS_notify_jvmti_events` to the >> jvmtiVTMSTransitionDisabler class as a replacement of the `VirtualThread` >> `notifyJvmtiEvents` variable. >> >> Implementing the same methods as C1 intrinsics can be needed in the future >> but is a low priority for now. >> >> Testing: >> - Ran mach5 tiers 1-6. No regressions were found. > > Serguei Spitsyn has updated the pull request incrementally with one > additional commit since the last revision: > > minor tweaks in intrisics implementation The most important case is when there is no JVMTI env. If I read the changes correctly, the overhead for park/continue changes from one volatile-read (notifyJvmtiEvents) to two plain-writes (JavaThread::_is_in_VTMS_transition). If a JVMTI env has been created then there is no benefit for the moment as there is still a call into the runtime to interact with JvmtiVTMSTransitionDisabler. So I think you are saying that is for follow-on PRs. ------------- PR: https://git.openjdk.org/jdk/pull/13054
