RFR: 8265461: G1: Forwarding pointer removal thread sizing [v2]

[Stefan Johansson]

On Wed, 21 Apr 2021 15:48:57 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Hi all,
>> 
>>   can I have reviews for this change that improves forwarding pointer removal handling by adding thread sizing to the work gang?
>> 
>> Since work is distributed per region at the moment, it does not make sense to start more threads than regions.
>> 
>> This can particularly help performance with object/region pinning.
>> 
>> Testing: tier1-3, using self-verification code
>> 
>> Thanks,
>>   Thomas
>
> Thomas Schatzl has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Added comment
>  - iwalulya lkorinth reviews

Looks good, just a couple of small comment you can deal with if you like.

src/hotspot/share/gc/g1/g1CollectedHeap.cpp line 3665:

> 3663: 
> 3664:   _expand_heap_after_alloc_failure = true;
> 3665:   Atomic::store(&_num_regions_failed_evacuation, 0u);

This could just be `_num_regions_failed_evacuation = 0;` right? Or am I missing something? It sticks out a bit and making one wonder if there is someone else change this value as well.

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Marked as reviewed by sjohanss (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3585