RFR: 8311883: [Genshen] Adaptive tenuring threshold

Y. Srinivas Ramakrishna ysr at openjdk.org
Tue Jul 11 18:02:28 UTC 2023


JDK-8311883 [GenShen] Adaptive tenuring

I am opening this previously draft PR for formal preliminary review. It has already benefited from review feedback from a code walkthrough of an earlier version of the code. Most of that feedback and the corrections thereof are to be found in the comments in this PR. I have addressed a large majority of those comments, and am working on the last one that I plan to address as part of this PR. For the ones that I don't plan to address in this PR, I will create follow up tickets. Those will be added in the responses for the remaining feedback comments recorded in this PR's conversation.

Preliminary testing w/SPECjbb didn't yield reliable performance data from which to infer any performance improvements stemming from enabling adaptive tenuring. I believe that was because of the way SPECjbb is run, which causes excessive degenerate and full gc's. I plan to collect SPECjbb numbers with a fixed lower max HBIR so as to be able to discern performance differences from this change, as well as Extremem workloads. Those will be added here once ready over the next few days.

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Commit messages:
 - jcheck clean: whitespace
 - Fix an assert because of youngg region iteration infelicity (and attendant
 - Deal with population of age 0 cohort that isn't subject to
 - Merge branch 'master' into adaptive_tenuring
 - Merge branch 'master' into adaptive_tenuring
 - Don't record age table info at evacuation when we do census at mark.
 - Lower the threshold of cohort mortality for longevity. Add a legal range
 - Open the legal window for ceiling and floor of tenuring threshold range
 - Prevent region ages from exceeding the maximum age expected of obects.
 - Code review changes: Part 4
 - ... and 61 more: https://git.openjdk.org/shenandoah/compare/ec727dab...95503db1

Changes: https://git.openjdk.org/shenandoah/pull/289/files
 Webrev: https://webrevs.openjdk.org/?repo=shenandoah&pr=289&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311883
  Stats: 911 lines in 27 files changed: 789 ins; 44 del; 78 mod
  Patch: https://git.openjdk.org/shenandoah/pull/289.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/289/head:pull/289

PR: https://git.openjdk.org/shenandoah/pull/289


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