RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v5]

[Johannes Bechberger]

On Mon, 26 May 2025 06:28:25 GMT, Johannes Bechberger <jbechberger at openjdk.org> wrote:

>> src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 590:
>> 
>>> 588:   // so samples might be skipped and we have to compute the actual period
>>> 589:   int64_t period = get_sampling_period() * (info->si_overrun + 1);
>>> 590:   request._cpu_time_period = Ticks(period / 1000000000.0 * JfrTime::frequency()) - Ticks(0);
>> 
>> Are you treating JfrTime::frequency() as nanos here? JfrTime::frequency() can be in ticks, hence not a valid conversion.
>
> Could you give me a hand with the conversion?

My code is the inversion of


template <typename TimeSource, const int unit>
inline double conversion(typename TimeSource::Type& value) {
  return (double)value * ((double)unit / (double)TimeSource::frequency());
}

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2106855512