RFR: 8271579: G1: Move copy before CAS in do_copy_to_survivor_space [v3]

[Hamlin Li]

On Fri, 6 Aug 2021 02:15:55 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Propose to move copy before CAS in do_copy_to_survivor_space, as we found this will improve G1 performance. Specjbb shows 3.7% in critical on aarch64, no change in max.
>> 
>> After this change copy_to_survivor in G1 is also aligned with PS's copy_to_survivor.
>
> Hamlin Li has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR.

Thanks for the testing, and feedback.

setting in run_multi.sh of specjbb2015:

GROUP_COUNT=4
TI_JVM_COUNT=1
JAVA_OPTS_BE="-server  -XX:+UseG1GC -Xmx50g -Xms50g -XX:ParallelGCThreads=25"

my test env is as below:

$ uname -a
Linux jvm-97 4.19.36-vhulk1907.1.0.h702.eulerosv2r8.aarch64 #1 SMP Mon Mar 16 00:02:15 UTC 2020 aarch64 aarch64 aarch64 GNU/Linux

$ lscpu
Architecture:        aarch64
Byte Order:          Little Endian
CPU(s):              128
On-line CPU(s) list: 0-127
Thread(s) per core:  1
Core(s) per socket:  64
Socket(s):           2
NUMA node(s):        4
Vendor ID:           0x48
Model:               0
Stepping:            0x1
BogoMIPS:            200.00
L1d cache:           64K
L1i cache:           64K
L2 cache:            512K
L3 cache:            65536K
NUMA node0 CPU(s):   0-31
NUMA node1 CPU(s):   32-63
NUMA node2 CPU(s):   64-95
NUMA node3 CPU(s):   96-127

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PR: https://git.openjdk.java.net/jdk/pull/4983