RFR: 8342818: Implement CPU Time Profiling for JFR [v4]

[Dean Long]

On Wed, 30 Oct 2024 19:34:23 GMT, Johannes Bechberger <jbechberger at openjdk.org> wrote:

>> This is the code for the [JEP draft: CPU Time based profiling for JFR].
>
> Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove min_valid_free_size_bytes

src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 221:

> 219:       _error = ERROR_NO_TOPFRAME;
> 220:       return;
> 221:     }

Wouldn't we end up with the same top frame if we started at the anchor frame instead?  In fact, the frame we want should always be the immediate caller of the anchor frame.  But I guess we need to check that the anchor frame is walkable.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1825257546