JEP : Cooperative JFR Sampling (porting work)

[Markus Gronlund]

Greetings again,

A more straightforward implementation has been pushed for JEP Cooperative JFR Sampling [1].

The ambition and the hopes are that the porting work involved will be much more straightforward.

In summary, the original design, premised on a preemptive move of the FP register in the interpreter, has been abandoned due to the complexities involved in its implementation for all platforms.

A more straightforward solution, which should involve significantly less porting work, has therefore been pushed to the PR [2].

Please take a look.

Thanks
Markus

[1] https://openjdk.org/jeps/8350338
[2] https://github.com/openjdk/jdk/pull/24296


-----Original Message-----
From: Markus Gronlund 
Sent: Monday, 12 May 2025 18:21
To: porters-dev <porters-dev at openjdk.org>
Cc: Markus Gronlund <markus.gronlund at oracle.com>
Subject: RE: JEP : Cooperative JFR Sampling (porting work)

Friendly reminder since the JEP has moved to Candidate.

Thanks
Markus

-----Original Message-----
From: porters-dev <porters-dev-retn at openjdk.org> On Behalf Of Markus Gronlund
Sent: Thursday, 24 April 2025 00:53
To: porters-dev <porters-dev at openjdk.org>
Subject: JEP : Cooperative JFR Sampling (porting work)

Greetings,

I am sending this to the porters-dev list as a heads-up for changes involved in JEP Cooperative JFR Sampling [1], which will affect ports if you support the JDK Flight Recorder (JFR) system.

The TemplateInterpreter will need a few changes; please see the files listed in the PR [2].

Technically, the InterpreterMacroAssembler::remove_activation() function will change to pre-emptively move the frame pointer (fp) to the sender frame before issuing a safepoint poll.

No stubs will be provided because the overall changes are extensive and completely change how the JFR system works regarding sampling.

Please feel free to send me patches, and I will incorporate them into the overall PR, or you can wait for a potential integration.

I appreciate your cooperation.
Markus

[1] https://openjdk.org/jeps/8350338
[2] https://github.com/openjdk/jdk/pull/24296