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JDK-8290870: NMT: Increase MallocSiteTable size and allocate it only when needed #9613

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tstuefe
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@tstuefe tstuefe commented Jul 22, 2022

MST size is too small. It was created with a very strict footprint limit, since it needed to be created statically and unconditionally.

However, JDK-8256844 reworked NMT initialization and now we can move MST initialization to after argument parsing. Since it is only needed with -XX:NativeMemoryTracking=detail, it makes sense to only conditionally allocate it.

And therefore we can afford to make it larger.

At the moment, it is 511 entries wide. A typical VM run (release VM, reasonably complex scenario) comes to ~3000-6000 entries. Atm the median bucket chain length is 6-8, which is a lot.

Increasing table size to ~4000 drops median bucket chain length to 1, which is nice.

Example, spring petclinic boot up:

before:

Bucket chain length distribution:
unused: 1
longest: 14
median: 7

with table size 4099:

Bucket chain length distribution:
unused: 1751
longest: 5
median: 1

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  • JDK-8290870: NMT: Increase MallocSiteTable size and allocate it only when needed

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bridgekeeper bot commented Jul 22, 2022

👋 Welcome back stuefe! 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.

@tstuefe tstuefe changed the title JDK-8290870: NMT: Increase MallocSiteTable size JDK-8290870: NMT: Increase MallocSiteTable size and allocate it only when needed Jul 22, 2022
@tstuefe tstuefe force-pushed the JDK-8290870-NMT-Increase-MallocSiteTable-size branch from 989ab3b to b098587 Compare July 22, 2022 12:06
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openjdk bot commented Jul 22, 2022

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

  • hotspot-runtime

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-runtime hotspot-runtime-dev@openjdk.org label Jul 22, 2022
@tstuefe tstuefe marked this pull request as ready for review July 22, 2022 18:46
@openjdk openjdk bot added the rfr Pull request is ready for review label Jul 22, 2022
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mlbridge bot commented Jul 22, 2022

Webrevs

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@zhengyu123 zhengyu123 left a comment

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LGTM

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openjdk bot commented Jul 22, 2022

@tstuefe 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:

8290870: NMT: Increase MallocSiteTable size and allocate it only when needed

Reviewed-by: zgu, dholmes

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 7 new commits pushed to the master branch:

  • 0599a05: 8290900: Build failure with Clang 14+ due to function warning attribute
  • 987656d: 8289471: Issue in Initialization of keys in ErrorMsg.java and XPATHErrorResources.java
  • 2660a92: 8290893: ProblemList java/lang/ClassLoader/loadLibraryUnload/LoadLibraryUnload
  • ef8486a: 8286270: [java.desktop] Replace color search in XColors with a switch statement
  • 62f2263: 8290861: Remove unused field URLJarFile.BUF_SIZE
  • b28f9da: 8290688: Optimize x86_64 nmethod entry barriers
  • 54854d9: 8256811: Delayed/missed jdwp class unloading events

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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 Jul 22, 2022
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Seems reasonable.

Thanks.

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tstuefe commented Jul 25, 2022

Thanks @zhengyu123 and @dholmes-ora !

/integrate

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openjdk bot commented Jul 25, 2022

Going to push as commit 852e71d.
Since your change was applied there have been 7 commits pushed to the master branch:

  • 0599a05: 8290900: Build failure with Clang 14+ due to function warning attribute
  • 987656d: 8289471: Issue in Initialization of keys in ErrorMsg.java and XPATHErrorResources.java
  • 2660a92: 8290893: ProblemList java/lang/ClassLoader/loadLibraryUnload/LoadLibraryUnload
  • ef8486a: 8286270: [java.desktop] Replace color search in XColors with a switch statement
  • 62f2263: 8290861: Remove unused field URLJarFile.BUF_SIZE
  • b28f9da: 8290688: Optimize x86_64 nmethod entry barriers
  • 54854d9: 8256811: Delayed/missed jdwp class unloading events

Your commit was automatically rebased without conflicts.

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

@tstuefe Pushed as commit 852e71d.

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

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Looks good. Thank you for doing this. (edit: I should have reloaded to see it was integrated but it still looks good).

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tstuefe commented Aug 1, 2022

Looks good. Thank you for doing this. (edit: I should have reloaded to see it was integrated but it still looks good).

Thank you :-)

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