8295354: Remove G1 incremental non-copy time calculation

[tschatzl]

Hi,

Currently G1 calculates the total non-copy time for young gen incrementally as regions are added to the young gen. The reason for this is that previously getting remembered set size has been expensive (i.e. part of non-copy time).

That is not the case any more since JDK 16 or so.

Further, actually in the calculation the remset work time does not need to be calculated on a per-region basis at all; first, it is incorrect as it does not remove duplicates, and additionally there is/has always been a total remembered set prediction anyway. (Which means the remembered set scan/merge time is considered multiple times).

So all this code can be removed.

Note that this change also fixes the same issue (double-counting of scan/merge time) for survivor regions.

Testing: tier1-3, manual testing wrt to pause time predictions which seem to be slightly better

Thanks,
Thomas

---

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Issue

• JDK-8295354: Remove G1 incremental non-copy time calculation

Reviewers

• Albert Mingkun Yang (@albertnetymk - Reviewer)
• Ivan Walulya (@walulyai - Reviewer)

Reviewing

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[openjdk]

@tschatzl This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8295354: Remove G1 incremental non-copy time calculation

Reviewed-by: ayang, iwalulya

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 18 new commits pushed to the master branch:

• 8836b92: 8296226: Add constructors (String,Throwable) and (Throwable) to InvalidParameterException
• 51f8e9b: 8296443: NMT: Remove cmdline_tracking_level handling code
• 087cedc: 8295261: RISC-V: Support ReductionV instructions for Vector API
• 556377a: 8296270: Memory leak in ClassLoader::setup_bootstrap_search_path_impl
• c2f7638: 8296335: Fix accessibility manual test instruction
• 91292d5: 8286301: Port JEP 425 to RISC-V
• 581133a: 8294696: BufferedInputStream.transferTo should drain buffer when mark set
• d8573b2: 8294488: Delete KCMS transforms wrappers
• f857f79: 8015739: Background of JInternalFrame is located out of JInternalFrame
• b847fb6: 8296414: [BACKOUT] JDK-8295319: pending_cards_at_gc_start doesn't include cards in thread buffers
• ... and 8 more: https://git.openjdk.org/jdk/compare/12316829b48c58e4509026543a3f2b50a57a439f...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[tschatzl]

Thanks @walulyai @albertnetymk for your reviews
/integrate

[openjdk]

Going to push as commit d634dde.
Since your change was applied there have been 18 commits pushed to the master branch:

• 8836b92: 8296226: Add constructors (String,Throwable) and (Throwable) to InvalidParameterException
• 51f8e9b: 8296443: NMT: Remove cmdline_tracking_level handling code
• 087cedc: 8295261: RISC-V: Support ReductionV instructions for Vector API
• 556377a: 8296270: Memory leak in ClassLoader::setup_bootstrap_search_path_impl
• c2f7638: 8296335: Fix accessibility manual test instruction
• 91292d5: 8286301: Port JEP 425 to RISC-V
• 581133a: 8294696: BufferedInputStream.transferTo should drain buffer when mark set
• d8573b2: 8294488: Delete KCMS transforms wrappers
• f857f79: 8015739: Background of JInternalFrame is located out of JInternalFrame
• b847fb6: 8296414: [BACKOUT] JDK-8295319: pending_cards_at_gc_start doesn't include cards in thread buffers
• ... and 8 more: https://git.openjdk.org/jdk/compare/12316829b48c58e4509026543a3f2b50a57a439f...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tschatzl Pushed as commit d634dde.

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