8275055: Improve HeapRegionRemSet::split_card() #5895

tschatzl · 2021-10-11T15:11:12Z

Hi all,

can I have reviews for this small change that improves HeapRegionRemSet::split_card() by reducing the number of (direct and indirect) memory accesses for it. It is hard to actually measure improvements because it's only called in concurrent code. So no particular improvements measured.

It also prepares that method for virtualizing the remembered set containers, allowing arbitrarily large heap region sizes JDK-8275056. This change is required then because the splitting of a card index into "region" and "card within region" should not be dependent on heap regions.

Testing: gha, gc/g1 local testing.

Thanks,
Thomas

Progress

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Issue

JDK-8275055: Improve HeapRegionRemSet::split_card()

Reviewers

Stefan Johansson (@kstefanj - Reviewer) ⚠️ Review applies to 765ea50
Albert Mingkun Yang (@albertnetymk - Reviewer)

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jdk pull/5895/head:pull/5895
$ git checkout pull/5895

Update a local copy of the PR:
$ git checkout pull/5895
$ git pull https://git.openjdk.java.net/jdk pull/5895/head

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Checkout this PR locally:
$ git pr checkout 5895

View PR using the GUI difftool:
$ git pr show -t 5895

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Download this PR as a diff file:
https://git.openjdk.java.net/jdk/pull/5895.diff

bridgekeeper · 2021-10-11T15:12:34Z

👋 Welcome back tschatzl! 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 · 2021-10-11T15:14:44Z

@tschatzl 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.

mlbridge · 2021-10-11T15:25:28Z

Webrevs

kstefanj

Looks good, but I would like us to come up with better naming for the limit.

src/hotspot/share/gc/g1/heapRegionRemSet.cpp

kstefanj

Looks good.

kstefanj · 2021-10-13T19:41:56Z

src/hotspot/share/gc/g1/g1CardSetContainers.hpp

@@ -177,6 +177,10 @@ class G1CardSetContainer {
  void set_next(G1CardSetContainer* next) {
    _next = next;
  }
+
+  // Maximum size of the entries of any G1CardSetContainer in bits.


This first can be removed now.

openjdk · 2021-10-13T19:45:17Z

@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:

8275055: Improve HeapRegionRemSet::split_card()

Reviewed-by: sjohanss, ayang

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 141 new commits pushed to the master branch:

35e5bb5: 8269336: Malformed jdk.serialFilter incorrectly handled
043cde2: 8275319: java.net.NetworkInterface throws java.lang.Error instead of SocketException
a91a0a5: 8233724: Remove -Wc++14-compat warning suppression in operator_new.cpp
1271fbf: 8248584: Enable CHECK_UNHANDLED_OOPS for Windows fastdebug builds
135cf3c: 8275439: Remove PrintVtableStats
50a5723: 8274910: Compile in G1 evacuation failure injection code based on define
5454a76: 8275273: Add missing HtmlStyle documentation
bd0bed7: 8273317: crash in cmovP_cmpP_zero_zeroNode::bottom_type()
77b2789: 7124287: [macosx] JTableHeader doesn't get focus after pressing F8 key
c24fb85: 8275512: Upgrade required version of jtreg to 6.1
... and 131 more: https://git.openjdk.java.net/jdk/compare/c032186b421c64b44397cb7aa101b40e5f93dfff...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.

kstefanj · 2021-10-14T08:36:58Z

👍

src/hotspot/share/gc/g1/g1CardSetContainers.cpp

src/hotspot/share/gc/g1/g1CardSetContainers.hpp

src/hotspot/share/gc/g1/heapRegionRemSet.inline.hpp

albertnetymk

_heap_base_address feels more natural to live in G1CollectedHeap. Anyway, this is very subjective.

tschatzl · 2021-10-20T15:31:59Z

_heap_base_address feels more natural to live in G1CollectedHeap. Anyway, this is very subjective.

The local cached copy is intentional: we do not want the extra indirection via G1CollectedHeap::heap(); otherwise we could simply use G1CollectedHeap::heap()->reserved().start() there instead.

tschatzl · 2021-10-20T15:32:47Z

Thanks @albertnetymk @kstefanj and @kimbarrett for your reviews.

/integrate

openjdk · 2021-10-20T15:34:12Z

Going to push as commit 7e28bdd.
Since your change was applied there have been 141 commits pushed to the master branch:

35e5bb5: 8269336: Malformed jdk.serialFilter incorrectly handled
043cde2: 8275319: java.net.NetworkInterface throws java.lang.Error instead of SocketException
a91a0a5: 8233724: Remove -Wc++14-compat warning suppression in operator_new.cpp
1271fbf: 8248584: Enable CHECK_UNHANDLED_OOPS for Windows fastdebug builds
135cf3c: 8275439: Remove PrintVtableStats
50a5723: 8274910: Compile in G1 evacuation failure injection code based on define
5454a76: 8275273: Add missing HtmlStyle documentation
bd0bed7: 8273317: crash in cmovP_cmpP_zero_zeroNode::bottom_type()
77b2789: 7124287: [macosx] JTableHeader doesn't get focus after pressing F8 key
c24fb85: 8275512: Upgrade required version of jtreg to 6.1
... and 131 more: https://git.openjdk.java.net/jdk/compare/c032186b421c64b44397cb7aa101b40e5f93dfff...master

Your commit was automatically rebased without conflicts.

openjdk · 2021-10-20T15:34:31Z

@tschatzl Pushed as commit 7e28bdd.

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

Optimize HeapRegionRemSet::split_card

d59d3fc

openjdk bot added the hotspot-gc hotspot-gc-dev@openjdk.org label Oct 11, 2021

tschatzl marked this pull request as ready for review October 11, 2021 15:20

openjdk bot added the rfr Pull request is ready for review label Oct 11, 2021

kstefanj suggested changes Oct 13, 2021

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src/hotspot/share/gc/g1/heapRegionRemSet.cpp Outdated Show resolved Hide resolved

sjohanss review

765ea50

kstefanj approved these changes Oct 13, 2021

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openjdk bot added the ready Pull request is ready to be integrated label Oct 13, 2021

sjohanss review2

615bf7c

kimbarrett suggested changes Oct 18, 2021

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tschatzl added 2 commits October 19, 2021 11:31

kbarrett review

2825a49

Fix windows compilation

139ad54

albertnetymk approved these changes Oct 20, 2021

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openjdk bot closed this Oct 20, 2021

openjdk bot added integrated Pull request has been integrated and removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Oct 20, 2021

tschatzl deleted the submit/8275055-optimize-split branch October 21, 2021 13:37

8275055: Improve HeapRegionRemSet::split_card() #5895

8275055: Improve HeapRegionRemSet::split_card() #5895

tschatzl commented Oct 11, 2021 •

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8275055: Improve HeapRegionRemSet::split_card() #5895

8275055: Improve HeapRegionRemSet::split_card() #5895

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tschatzl commented Oct 11, 2021 • edited by openjdk bot

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