RFR: 8361726: Shenandoah: More detailed evacuation instrumentation

[Y. Srinivas Ramakrishna]

On Wed, 9 Jul 2025 17:52:08 GMT, William Kemper <wkemper at openjdk.org> wrote:

> Shenandoah has `product only` instrumentation to track evacuation performance. This change introduces more detail by categorizing each evacuation as young, old or promotion.

Approved, modulo a few nits.

The extra detail is useful!

> Shenandoah has `product only` instrumentation to track evacuation performance.

Did you mean to say `non-product` instead of `product only` above?

src/hotspot/share/gc/shenandoah/shenandoahEvacTracker.cpp line 112:

> 110:   st->print("Young: "); _young.print_on(st);
> 111:   st->print("Old: "); _old.print_on(st);
> 112:   st->print("Promotion: "); _promotion.print_on(st);

Nit: I might switch the order of Promote & Old.

src/hotspot/share/gc/shenandoah/shenandoahEvacTracker.hpp line 78:

> 76: 
> 77:   void begin_evacuation(size_t bytes, ShenandoahAffiliation from, ShenandoahAffiliation to);
> 78:   void end_evacuation(size_t bytes, ShenandoahAffiliation from, ShenandoahAffiliation to);

1 line documentation comment for each, please.

src/hotspot/share/gc/shenandoah/shenandoahEvacTracker.hpp line 101:

> 99: 
> 100:   void begin_evacuation(Thread* thread, size_t bytes, ShenandoahAffiliation from, ShenandoahAffiliation to);
> 101:   void end_evacuation(Thread* thread, size_t bytes, ShenandoahAffiliation from, ShenandoahAffiliation to);

1 line documentation comment for each, please.

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

Marked as reviewed by ysr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26222#pullrequestreview-3045297809
PR Review Comment: https://git.openjdk.org/jdk/pull/26222#discussion_r2224126864
PR Review Comment: https://git.openjdk.org/jdk/pull/26222#discussion_r2224124878
PR Review Comment: https://git.openjdk.org/jdk/pull/26222#discussion_r2224125359