Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

8290376: G1: Refactor G1MMUTracker::when_sec #9517

Closed
wants to merge 4 commits into from

Conversation

albertnetymk
Copy link
Member

@albertnetymk albertnetymk commented Jul 15, 2022

Introducing a more intuitive implementation.

This PR consists of two commits: the first adds the new algorithm and verifies the result is same as before. The second commit removes the old implementation.

Test: tier1-6 for the first commit.


Progress

  • Change must be properly reviewed (1 review required, with at least 1 Reviewer)
  • Change must not contain extraneous whitespace
  • Commit message must refer to an issue

Issue

Reviewers

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk pull/9517/head:pull/9517
$ git checkout pull/9517

Update a local copy of the PR:
$ git checkout pull/9517
$ git pull https://git.openjdk.org/jdk pull/9517/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 9517

View PR using the GUI difftool:
$ git pr show -t 9517

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/9517.diff

@bridgekeeper
Copy link

bridgekeeper bot commented Jul 15, 2022

👋 Welcome back ayang! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

@openjdk openjdk bot changed the title 8290376 8290376: G1: Refactor G1MMUTracker::when_sec Jul 15, 2022
@openjdk openjdk bot added the rfr Pull request is ready for review label Jul 15, 2022
@openjdk
Copy link

openjdk bot commented Jul 15, 2022

@albertnetymk The following label will be automatically applied to this pull request:

  • hotspot-gc

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

@openjdk openjdk bot added the hotspot-gc hotspot-gc-dev@openjdk.org label Jul 15, 2022
@mlbridge
Copy link

mlbridge bot commented Jul 15, 2022

Webrevs

@bridgekeeper
Copy link

bridgekeeper bot commented Aug 12, 2022

@albertnetymk This pull request has been inactive for more than 4 weeks and will be automatically closed if another 4 weeks passes without any activity. To avoid this, simply add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

// Earliest end time of a hypothetical pause starting now, taking pause_time.
double earliest_end_time = current_timestamp + adjusted_pause_time;
double gc_time_in_recent_time_slice = calculate_gc_time(earliest_end_time) + adjusted_pause_time;
// Clamp it by max
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
// Clamp it by max
// If the pause is over the maximum, just assume that it's the maximum.

I would prefer the original comment as it explicitly states that this is a conscious decision.

// Focusing on GC events that are inside [limit, current_timestamp], we iterate
// over them from the newest to the oldest (right-to-left in the diagram) and
// try to locate the timestamp annotated with ^, so that the accumulated GC
// time inside [deficit, current_timestamp], is equal to gc_budget. Next,
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

gc_budget is not defined anywhere in this comment or the diagram. This is confusing.

int index = _tail_index;
while ( 1 ) {
double limit = current_timestamp + pause_time - _time_slice;
// Iterate from newest to oldest
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
// Iterate from newest to oldest
// Iterate from newest to oldest.

if (is_double_leq_0(gc_time_to_pass)) {
return elem->end_time() + (_time_slice + gc_time_to_pass) - earliest_end_time;
}
// Outside the window
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
// Outside the window
// Outside the window.

}

double duration = (elem->end_time() - MAX2(elem->start_time(), limit));
// Would exceed the budget; strictly greater than
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
// Would exceed the budget; strictly greater than
// This duration would exceed the budget. Check for strictly greater than.

Not sure what the "[Check for ]strictly greater than" adds, but it's okay.

double duration = (elem->end_time() - MAX2(elem->start_time(), limit));
// Would exceed the budget; strictly greater than
if (duration > gc_budget) {
// The timestamp where a budget deficit occurs.
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
// The timestamp where a budget deficit occurs.
// This GC event contains the timestamp where the budget deficit occurs.

}

// No enough gc time inside the window; a budget surplus
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
// No enough gc time inside the window; a budget surplus
// Not enough gc time spent inside the window, we have a budget surplus.

Copy link
Contributor

@tschatzl tschatzl left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Lgtm.

@openjdk
Copy link

openjdk bot commented Aug 24, 2022

@albertnetymk 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:

8290376: G1: Refactor G1MMUTracker::when_sec

Reviewed-by: tschatzl, 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 466 new commits pushed to the master branch:

  • 5a20bc4: 8292715: Cleanup Problemlist
  • 7b81a9c: 8289764: gc/lock tests failed with "OutOfMemoryError: Java heap space: failed reallocation of scalar replaced objects"
  • 76ee549: 8292329: Enable CDS shared heap for zero builds
  • 14623c6: 8292739: Invalid legacy entries may be returned by Provider.getServices() call
  • 568be58: 8290469: Add new positioning options to PassFailJFrame test framework
  • 69448f9: 8292679: Simplify thread creation in gtest and port 2 tests to new way
  • 3c2289d: 8215916: The failure reason of an optional JAAS LoginModule is not logged
  • 71ab5c9: 8292816: GPL Classpath exception missing from assemblyprefix.h
  • c062397: 8292713: Unsafe.allocateInstance should be intrinsified without UseUnalignedAccesses
  • a45a4b9: 8292194: G1 nmethod entry barrier disarm value wraps around too early
  • ... and 456 more: https://git.openjdk.org/jdk/compare/757a742ac78a6ececcc4f9f542f8f7108968129d...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.

@openjdk openjdk bot added the ready Pull request is ready to be integrated label Aug 24, 2022
@albertnetymk
Copy link
Member Author

Thanks for the review.

/integrate

@openjdk
Copy link

openjdk bot commented Aug 25, 2022

Going to push as commit dc7e256.
Since your change was applied there have been 466 commits pushed to the master branch:

  • 5a20bc4: 8292715: Cleanup Problemlist
  • 7b81a9c: 8289764: gc/lock tests failed with "OutOfMemoryError: Java heap space: failed reallocation of scalar replaced objects"
  • 76ee549: 8292329: Enable CDS shared heap for zero builds
  • 14623c6: 8292739: Invalid legacy entries may be returned by Provider.getServices() call
  • 568be58: 8290469: Add new positioning options to PassFailJFrame test framework
  • 69448f9: 8292679: Simplify thread creation in gtest and port 2 tests to new way
  • 3c2289d: 8215916: The failure reason of an optional JAAS LoginModule is not logged
  • 71ab5c9: 8292816: GPL Classpath exception missing from assemblyprefix.h
  • c062397: 8292713: Unsafe.allocateInstance should be intrinsified without UseUnalignedAccesses
  • a45a4b9: 8292194: G1 nmethod entry barrier disarm value wraps around too early
  • ... and 456 more: https://git.openjdk.org/jdk/compare/757a742ac78a6ececcc4f9f542f8f7108968129d...master

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Aug 25, 2022
@openjdk openjdk bot closed this Aug 25, 2022
@openjdk openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Aug 25, 2022
@openjdk
Copy link

openjdk bot commented Aug 25, 2022

@albertnetymk Pushed as commit dc7e256.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

@albertnetymk albertnetymk deleted the g1-mmu branch August 25, 2022 09:16
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
hotspot-gc hotspot-gc-dev@openjdk.org integrated Pull request has been integrated
3 participants