RFR: 8288474: Move EventContinuationFreezeOld from try_freeze_fast to freeze_slow

[Ron Pressler]

On Tue, 13 Sep 2022 20:22:58 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> This moves the event ContinuationFreezeOld to freeze_slow so it's reported on the different paths to freeze_slow, and renames the events Continuation*Old/Continuation*Slow and Continuation*Young/Continuation*Fast to reflect that they're on the fast/slow paths.  I turned on CONT_JFR and fixed some bugs and turned it back off again.  Some output:
> 
> $ jfr summary hotspot-pid-31671-id-1-2022_09_13_19_42_01.jfr | grep Continuation
>  jdk.ContinuationThaw                    12193        211929
>  jdk.ContinuationThawFast                10139        165420
>  jdk.ContinuationFreeze                   3196         57135
>  jdk.ContinuationFreezeFast               2788         46397
>  jdk.ContinuationThawSlow                 2054         28543
>  jdk.ContinuationFreezeSlow                408          5688
> 
> Tested locally and with tier7 which seems to run JFR tests.

src/hotspot/share/runtime/continuationFreezeThaw.cpp line 723:

> 721: #if CONT_JFR
> 722:   EventContinuationFreezeSlow e;
> 723:   if (e.should_commit()) {

Committing the event should happen at the end of the method to measure the time.

src/hotspot/share/runtime/continuationFreezeThaw.cpp line 1855:

> 1853: #if CONT_JFR
> 1854:   EventContinuationThawSlow e;
> 1855:   if (e.should_commit()) {

Committing the event should be done at the end of the method.

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PR: https://git.openjdk.org/jdk/pull/10254