RFR: 8295657: SA: Allow larger object alignments [v2]

Chris Plummer cjplummer at openjdk.org
Thu Oct 20 17:39:23 UTC 2022


On Thu, 20 Oct 2022 09:40:55 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Found this when working on JOL support ([CODETOOLS-7903364](https://bugs.openjdk.org/browse/CODETOOLS-7903364)). If you try to attach to VM running with -XX:ObjectAlignmentInBytes=32, then SA would fail with:
>> 
>> 
>> Caused by: java.lang.RuntimeException: Object alignment 32 not yet supported
>> at jdk.hotspot.agent/sun.jvm.hotspot.runtime.VM.<init>(VM.java:510)
>> at jdk.hotspot.agent/sun.jvm.hotspot.runtime.VM.initialize(VM.java:544)
>> at jdk.hotspot.agent/sun.jvm.hotspot.HotSpotAgent.setupVM(HotSpotAgent.java:444)
>> 
>> 
>> This code was added by [JDK-6916623](https://bugs.openjdk.org/browse/JDK-6916623), but I don't see a reason why it should only handle 8 and 16 byte alignment.
>> 
>> Additional testing:
>>  - [x] New regression test
>>  - [x] Linux x86_64 fastdebug `serviceability/sa`, with the combination of:
>>     - different `-XX:ObjectAlignmentInBytes=`: 8, 16, 32, 64, 128, 256
>>     - different GCs: Serial, Parallel, G1
>>  - [ ] Linux x86_64 fastdebug `sun/tools/jhsdb`, with the combination of:
>>     - different `-XX:ObjectAlignmentInBytes=`: 8, 16, 32, 64, 128, 256
>>     - different GCs: Parallel, G1
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
> 
>  - Drop range check
>  - Merge branch 'master' into JDK-8295657-sa-obj-align
>  - Simplify test
>  - Basic fix

Looks good.

-------------

Marked as reviewed by cjplummer (Reviewer).

PR: https://git.openjdk.org/jdk/pull/10762


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