Hi, > are you aware of JDK-8287496 ? > https://bugs.openjdk.java.net/browse/JDK-8287496
Yes I noticed it. Alan recommended to test it with jdk_loom and hotspot_loom tests. I have done that just now on a ppc64le box. The tests in jdk_loom succeed. There are test failures in hotspot_loom but all in serviceability/jvmti/(events|vthread). I understand that this is to be expected and will be handled in a follow-up by adding "@requires vm.continuations" to these tests. So Alan's fallback seems to work on ppc64le which is good to know :) Thanks, Richard. From: Remi Forax <fo...@univ-mlv.fr> Date: Thursday, 2. June 2022 at 18:50 To: Reingruber, Richard <richard.reingru...@sap.com> Cc: jdk-dev <jdk-...@openjdk.java.net>, porters-dev@openjdk.java.net <porters-dev@openjdk.java.net>, loom-dev <loom-...@openjdk.java.net> Subject: Re: State of the ppc64le port of JEP 425: Virtual Threads (Preview) Hi Richard, are you aware of JDK-8287496 ? https://bugs.openjdk.java.net/browse/JDK-8287496 It should help you to get a working first implementation for jdk 19. regards, Rémi ----- Original Message ----- > From: "Reingruber, Richard" <richard.reingru...@sap.com> > To: "jdk-dev" <jdk-...@openjdk.java.net>, porters-dev@openjdk.java.net, > "loom-dev" <loom-...@openjdk.java.net> > Sent: Thursday, June 2, 2022 1:38:19 PM > Subject: State of the ppc64le port of JEP 425: Virtual Threads (Preview) > Hi, > > I learned today that preview features _must_ be implemented by a port in an > OpenJDK release [1]. > > Unfortunately I have to inform you that I don't think the ppc64le port I'm > currently working on will be ready in the JDK19 time frame. > > When I started the work (Jan. or Dec. I think) I expected to finish it before > summer. Even after the last status update [2] I thought I could make it. But > with the difficulties I still experience and being 6-8 weeks out of office in > summer it is now rather unlikely. And until this morning myself (and actually > also my colleagues) assumed this would only be a minor issue. > > Current Status of the Port: > > * UseContinuationFastPath is disabled > > * Basic tests where sequences of interpreted and compiled frames with quite > some > variations are frozen and thawed succeed. > > * GC with stack chunks on the java heap succeed. > > * Basic exception handling tests succeed. > > * Basic tests exercising compiled java calls with stack arguments succeed but > need to be revisited because there are issues. > > [3] is a selection of test cases that I use in development. > [4] is the most recent version of the ppc64le port > > Main Technical Problems > > * Shared code makes use of the 'unextended sp' of java frames. This breaks the > platform abstraction as it makes assumptions on where to find, e.g., stack > arguments relative to the unextended sp. > > * There are non-obvious interdependencies in the code which make it difficult > to > fix an issue. In an attempt to fix a problem I often have regressions because > I missed adaptations of dependent parts. And then it it is extremely tedious > to find the cause of the regression running tests and analyzing very long > trace output. > > * Currently I see that the handling of stack arguments of compiled java > methods > works in quite some cases (see [3]) but there are cases where it > doesn't. Trying alternative approaches means going through the tedious and > time consuming process described above. > > * Lack of documentation. Heavily templatized implementation. > > These problems (except the last) could not be foreseen. From a high level the > port simply needs to copy frames between stack and heap and provide some > assembler glue code. As I know now it is actually a high effort to get the > deatils tuned right. > > Thanks, Richard. > > [1] Ports _must_ implement preview features in thread "What should the > relationship between ports and developers of large projects be?" > https://mail.openjdk.java.net/pipermail/jdk-dev/2022-May/006635.html > [2] State of the ppc64le loom port as of April 14 > https://mail.openjdk.java.net/pipermail/loom-dev/2022-April/004197.html > [3] BasicExp.java tests driving development of the port > > https://github.com/reinrich/loom/blob/3286bc8b72401dbccac59c994919fc425a51cb52/test/jdk/jdk/internal/vm/Continuation/BasicExp.java > [4] Most recent version of the ppc64le loom port > https://github.com/reinrich/loom/commits/ppc_port
