8252645: Change time measurements in G1ServiceThread to only account remembered set work #1447

kstefanj · 2020-11-26T10:35:35Z

Please review this change to move the timing of how much time is spent doing remembered set sampling into the task doing the sampling. The timing has historically been part of the service thread, because in the past the only thing the thread did was sampling. Now when both uncommit work and periodic GC scheduling has been added, the timing needs to be moved into the sampling task.

I've also slightly changed the output using this information to:

[0,295s][trace][gc,remset   ] GC(0)   Sampling task time (ms)
[0,295s][trace][gc,remset   ] GC(0)           0,000

Instead of the old:

[0,301s][trace][gc,remset   ] GC(0)   Service thread time (s)
[0,301s][trace][gc,remset   ] GC(0)           0,00

I decided to change the unit to ms because the time spent doing sampling is very small and is better measured in milliseconds. When doing so I also went with three decimals since this is what we normally do for milliseconds.

Progress

Change must not contain extraneous whitespace
Commit message must refer to an issue
Change must be properly reviewed

Testing

	Linux additional	Linux x64	Linux x86	Windows x64	macOS x64
Build	✔️ (8/8 passed)	✔️ (2/2 passed)	✔️ (2/2 passed)	✔️ (2/2 passed)	✔️ (2/2 passed)
Test (tier1)		❌ (1/9 failed)	❌ (2/9 failed)	✔️ (9/9 passed)	✔️ (9/9 passed)

Failed test tasks

Issue

JDK-8252645: Change time measurements in G1ServiceThread to only account remembered set work

Reviewers

Albert Mingkun Yang (@albertnetymk - Author) ⚠️ Review applies to 2e2c0b5
Thomas Schatzl (@tschatzl - Reviewer) ⚠️ Review applies to 2e2c0b5

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1447/head:pull/1447
$ git checkout pull/1447

…remembered set work

bridgekeeper · 2020-11-26T10:35:51Z

👋 Welcome back sjohanss! 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 · 2020-11-26T10:36:52Z

@kstefanj 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 · 2020-11-26T10:40:01Z

Webrevs

01: Full - Incremental (c9dc99b)
00: Full (2e2c0b5)

tschatzl

Looks good apart from these minor nits.

tschatzl · 2020-11-26T16:27:43Z

src/hotspot/share/gc/g1/g1RemSet.cpp

@@ -482,23 +482,6 @@ class G1RemSetScanState : public CHeapObj<mtGC> {
  }
 };

-G1RemSet::G1RemSet(G1CollectedHeap* g1h,


Not completely sure why this moved but not G1RemSet::initialize() below.

The destructor had to move to see the type and I obviously took the constructor but missed initialize(). Certainly makes sense to move that one too.

tschatzl · 2020-11-26T16:27:43Z

src/hotspot/share/gc/g1/g1RemSet.cpp

+  assert(_sampling_task != NULL, "Must have been initialized");
+  return _sampling_task->vtime_accum();
+}
+


Extra newline.

openjdk · 2020-11-26T16:28:28Z

@kstefanj 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:

8252645: Change time measurements in G1ServiceThread to only account remembered set work

Reviewed-by: ayang, tschatzl

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 11 new commits pushed to the master branch:

2215e5a: 8255351: Add detection for Graviton 2 CPUs
62d72de: 8220730: sun.security.provider.SecureRandom default constructor has wrong documentation
4e43b28: 8256359: AArch64: runtime/ReservedStack/ReservedStackTestCompiler.java fails
6e00622: 8256488: [aarch64] Use ldpq/stpq instead of ld4/st4 for small copies in StubGenerator::copy_memory
a93841a: 8255277: randomDelay in DrainDeadlockT and LoggingDeadlock do not randomly delay
2d30a10: 8257069: C2: Clarify and sanity test RegMask/RegMaskIterator
0a5de50: 8257151: ZGC: Simplify ZVerify
bf66d73: 8257073: ZGC: Try forward object before retaining page
1b3aa3a: 8256831: MIPS Zero builds fail with undefined __atomic_compare_exchange_8
734d3c3: 8256862: Several java/foreign tests fail on x86_32 platforms
... and 1 more: https://git.openjdk.java.net/jdk/compare/f6d6a07c30d8dd1965ff3007707879719b82c6c0...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 · 2020-11-27T08:26:16Z

Still good. Thanks.

kstefanj · 2020-11-27T08:44:04Z

/integrate

kstefanj · 2020-11-27T08:44:25Z

Thanks @tschatzl and @albertnetymk for the reviews.

openjdk · 2020-11-27T08:45:00Z

@kstefanj Since your change was applied there have been 13 commits pushed to the master branch:

a3eec39: 8257181: s390x builds are very noisy with gc-sections messages
9a468d8: 8256757: Incorrect MachCallRuntimeNode::ret_addr_offset() for CallLeafNoFP on x86_32
2215e5a: 8255351: Add detection for Graviton 2 CPUs
62d72de: 8220730: sun.security.provider.SecureRandom default constructor has wrong documentation
4e43b28: 8256359: AArch64: runtime/ReservedStack/ReservedStackTestCompiler.java fails
6e00622: 8256488: [aarch64] Use ldpq/stpq instead of ld4/st4 for small copies in StubGenerator::copy_memory
a93841a: 8255277: randomDelay in DrainDeadlockT and LoggingDeadlock do not randomly delay
2d30a10: 8257069: C2: Clarify and sanity test RegMask/RegMaskIterator
0a5de50: 8257151: ZGC: Simplify ZVerify
bf66d73: 8257073: ZGC: Try forward object before retaining page
... and 3 more: https://git.openjdk.java.net/jdk/compare/f6d6a07c30d8dd1965ff3007707879719b82c6c0...master

Your commit was automatically rebased without conflicts.

Pushed as commit ee99686.

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

8252645: Change time measurements in G1ServiceThread to only account …

2e2c0b5

…remembered set work

openjdk bot added the rfr label Nov 26, 2020

openjdk bot added the hotspot-gc label Nov 26, 2020

albertnetymk approved these changes Nov 26, 2020

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tschatzl approved these changes Nov 26, 2020

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openjdk bot added the ready label Nov 26, 2020

Thomas review

c9dc99b

openjdk bot closed this Nov 27, 2020

openjdk bot added integrated and removed ready rfr labels Nov 27, 2020

kstefanj deleted the 8252645-timing-remset-sampling branch Nov 27, 2020

8252645: Change time measurements in G1ServiceThread to only account remembered set work #1447

8252645: Change time measurements in G1ServiceThread to only account remembered set work #1447

kstefanj commented Nov 26, 2020 •

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8252645: Change time measurements in G1ServiceThread to only account remembered set work #1447

8252645: Change time measurements in G1ServiceThread to only account remembered set work #1447

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kstefanj commented Nov 26, 2020 • edited by openjdk[bot] bot

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