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

[Johannes Bechberger]

On Sun, 25 May 2025 15:33:19 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> src/hotspot/share/jfr/recorder/service/jfrEventThrottler.cpp line 118:
>> 
>>> 116: bool JfrEventThrottler::accept(JfrEventId event_id, int64_t timestamp /* 0 */) {
>>> 117:   JfrEventThrottler* const throttler = for_event(event_id);
>>> 118:   if (throttler == nullptr) {
>> 
>> Unfortunately, two checks have been introduced on the throttler hot path. Can we avoid this in some way?
>
> Can the settings system be updated so the throttle bit is not set in the native settings struct?

I just created a throttler which is always disabled. This uses a bit more memory, but doesn't need any special handling for CPUTimeSample events.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2107188550