On Wed, 4 Jun 2025 17:54:50 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 incrementally with one > additional commit since the last revision: > > Improve disenroll src/hotspot/os/posix/signals_posix.cpp line 1511: > 1509: struct sigaction oact; > 1510: if (sigaction(sig, (struct sigaction*)nullptr, &oact) == -1) { > 1511: return nullptr; // signal not installed A comment is misleading: sigaction does not fail if a handler for the signal is not installed (i.e. the handler is SIG_IGN). src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 656: > 654: if ((prev_handler != SIG_DFL && prev_handler != SIG_IGN && > prev_handler != (void*)::handle_timer_signal) || > 655: PosixSignals::install_generic_signal_handler(SIG, > (void*)::handle_timer_signal) == (void*)-1) { > 656: log_error(jfr)("CPUTimeSample events will not be recorded: %p", > prev_handler); A message with some random hex address may look cryptic. Maybe make it a bit more user-friendly? E.g. Conflicting SIGPROF handler found: %p. CPUTimeSample events will not be recorded src/hotspot/share/jfr/periodic/sampling/jfrSampleRequest.cpp line 333: > 331: } > 332: } > 333: request._sample_ticks = JfrTicks::now(); For accurate correlation with other events, timestamp of a sample should be taken as early as possible, preferably in the beginning of `JfrCPUSamplerThread::handle_timer_signal` ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2127222795 PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2127266822 PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2127236706
