RFR: JDK-8289524: Add JFR JIT restart event [v2]

[Matthias Baesken]

On Wed, 6 Jul 2022 11:38:48 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

> Hi again Mathias, based on your observation that this does not really align well with the threshold parameter for SweepCodeCache and is a complement event to EventCodeCacheFull, I believe your original suggestion is better (an instant event, only for "jit restart"). I was slightly tripped up with the concept of a "JIT restart", because at this point the JIT is already stopped, as implied by EventCodeCacheFull. So "JIT restart" here contextually means, "JIT start", as in "start JITting code again". Do you know if we have an event that describes the CodeCache settings in terms of memory sizes so that the "freed memory" can be interpreted relative to it?

Hi Markus,  at least we store a couple of addresses in the EventCodeCacheFull  event.  Those could potentially be used for interpretation.
EventCodeCacheFull event;
event.set_startAddress((u8)heap->low_boundary());
event.set_commitedTopAddress((u8)heap->high());
event.set_reservedTopAddress((u8)heap->high_boundary());

-------------

PR: https://git.openjdk.org/jdk/pull/9334