RFR: 8342818: Implement CPU Time Profiling for JFR

[Markus Grönlund]

On Wed, 28 Aug 2024 16:47:21 GMT, Johannes Bechberger <jbechberger at openjdk.org> wrote:

> This is the code for the [JEP draft: CPU Time based profiling for JFR].

src/jdk.jfr/share/classes/jdk/jfr/internal/EventControl.java line 84:

> 82:             addControl(Threshold.NAME, defineThreshold(eventType));
> 83:         }
> 84:         if (eventType.hasStackTrace() && !eventType.isCPUTimeMethodSampling()) {

The second clause is not really needed, right? I don't think the CPUTimeMethodSampling event hasStacktrace() is true.

The event has a separate StackTrace field in the event, but that is not what is being checked here.

src/jdk.jfr/share/conf/jfr/profile.jfc line 195:

> 193:     <event name="jdk.CPUTimeSample">
> 194:       <setting name="enabled" control="method-sampling-enabled">false</setting>
> 195:       <setting name="throttle">10ms</setting>

Can a rate be given here instead of an absolute value? Otherwise, there is a mismatch between the default. jfc and the profile.jfc which seems quite unintuitive.

test/jdk/jdk/jfr/event/profiling/TestCPUTimeAndExecutionSample.java line 35:

> 33:  * @test
> 34:  * @key jfr
> 35:  * @requires vm.hasJFR

@requires vm.hasJFR & os.family == "linux" ?

test/jdk/jdk/jfr/event/profiling/TestCPUTimeSamplingLongPeriod.java line 35:

> 33:  * @test
> 34:  * @key jfr
> 35:  * @requires vm.hasJFR

@requires vm.hasJFR & os.family == "linux"?

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PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1822726454
PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1822731716
PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1822734759
PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1822736281