RFR: 8257145: Performance regression with -XX:-ResizePLAB after JDK-8079555 [v2]

[Stefan Johansson]

On Sun, 29 Nov 2020 15:21:09 GMT, Dongbo He <dongbohe at openjdk.org> wrote:

>> Hi,
>> 
>> this is the continuation of the review of the implementation for:
>> 
>> https://bugs.openjdk.java.net/browse/JDK-8257145
>
> Dongbo He has updated the pull request incrementally with one additional commit since the last revision:
> 
>   store the "default size" for the PLAB in the PLABStats

Looks good, just a few small things.

src/hotspot/share/gc/g1/g1CollectedHeap.cpp line 1410:

> 1408:   _archive_allocator(NULL),
> 1409:   _survivor_evac_stats("Young", YoungPLABSize, YoungPLABSize * ParallelGCThreads, PLABWeight),
> 1410:   _old_evac_stats("Old", OldPLABSize, OldPLABSize * ParallelGCThreads, PLABWeight),

I think you could leave those two unchanged and in the constructor for `G1EvacStats` do the multiplication with `ParallelGCThreads` for the desired value.

src/hotspot/share/gc/shared/plab.hpp line 173:

> 171: 
> 172:  public:
> 173:   PLABStats(const char* description, size_t default_plab_sz, size_t desired_net_plab_sz_, unsigned wt) :

Since you  are touching this line it would be nice to remove the trailing `_` in `desired_net_plab_sz_`.

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Changes requested by sjohanss (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1474