On Wed, 4 Jun 2025 11:18:52 GMT, Johannes Bechberger <jbechber...@openjdk.org> wrote:
>> This is the code for the [JEP 509: CPU Time based profiling for >> JFR](https://openjdk.org/jeps/509). >> >> Currently tested using [this test >> suite](https://github.com/parttimenerd/basic-profiler-tests). This runs >> profiles the [Renaissance](https://renaissance.dev/) benchmark with >> - ... different heap sizes >> - ... different GCs >> - ... different samplers (the standard JFR and the new CPU Time Sampler and >> both) >> - ... different JFR recording durations >> - ... different chunk-sizes > > Johannes Bechberger has updated the pull request with a new target base due > to a merge or a rebase. The pull request now contains 127 commits: > > - Merge branch 'master' into parttimenerd_cooperative_cpu_time_sampler > - Add error message on signal handler install failure > - Fix signal handler synchronization > - Improve > - Rename autoadapt > - Make process_cpu_time_request private and move up > - Reorder condition > - Tiny refactoring > - Restrict threads for which timers are created > - Fix tiny mistake > - ... and 117 more: https://git.openjdk.org/jdk/compare/7838321b...4fd4b673 src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 611: > 609: // increment the count of active signal handlers > 610: u4 old_value = Atomic::fetch_then_add(&_active_signal_handlers, (u4)1, > memory_order_acq_rel); > 611: if ((old_value & STOP_SIGNAL_BIT) != 0) { Combining stop signal with a counter is nice, you can then use `Atomic::cmpxchg` to avoid incrementing counter when the stop bit is set. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2126354062
