RFR: 8277893: Arraycopy stress tests

[Vladimir Kozlov]

On Mon, 29 Nov 2021 13:28:33 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> I would like to fork the new tests off the JDK-8150730. These tests were instrumental in capturing many bugs in my arraycopy work, and I think they are good on their own merit, because they provide a test for the current baseline and on-going minor improvements in arraycopy on all platforms, not only x86_64, and they might be cleanly backportable.
> 
> A brief tour of these tests:
> 
> - Tests all data types;
> - Tests small arrays exhaustively, which captures conjoint/disjoint cases, errors near the edges, etc;
> - Tests large arrays with fuzzing around powers of two and powers of ten, both conjoint and disjoint cases;
> - Tests all available compilation modes for arraycopy stubs; for example, running on AVX-512 enabled machine runs all versions down to `-XX:UseAVX=0 -XX:UseSSE=0` cases;
> - Tests with/without compressed oops mode -- theoretically only needed for `Object` copies, but Hotspot cobbles together int+coops and long+no-coops loops, so I decided to alternate coops mode for all data types;
> 
> My previous version used individual `@run` clauses for all configurations, but I think the Java driver is cleaner and easier to maintain.
> 
> Test times:
> 
> 
> # x86_64 (TR 3970X)
>   real	9m11.037s
>   user	78m2.766s
>   sys	0m19.873s
> 
> # x86_32 (TR 3970X)
>   real	13m39.054s
>   user	147m38.308s
>   sys	0m10.924s
> 
> # x86_64 (i5-11500)
>   real    41m32.622s
>   user    447m19.986s
>   sys     0m21.026s
> 
> # AArch64 (ThunderX2)
>   real	5m34.210s
>   user	45m16.015s
>   sys	0m24.723s
> 
> 
> Since these tests are quite long, especially on small machines, I hooked them up to `hotspot:tier3`.
> 
> Additional testing:
>  - [x] Linux x86_64 fastdebug `compiler/stress/arraycopy`
>  - [x] Linux x86_32 fastdebug `compiler/stress/arraycopy`
>  - [x] Linux AArch64 fastdebug `compiler/stress/arraycopy`

I assume that `test/micro/org/openjdk/bench/java/lang` micros cover all these cases. Otherwise you may need to add some.

test/hotspot/jtreg/TEST.groups line 183:

> 181: 
> 182: tier3_compiler = \
> 183:   compiler/arraycopy/stress

Can you introduce separate group for this? For example `hotspot_arraycopy_stress` and use it here.
I am fine with introduced `tier2|3_compiler` groups but it will help us in Oracle to have separate group for `arraycopy` so we can schedule its testing on proper machines.

test/hotspot/jtreg/compiler/arraycopy/stress/AbstractStressArrayCopy.java line 32:

> 30:      * Max array size to test.
> 31:      */
> 32:     static final int MAX_SIZE = 1024*1024 + 1;

Do we really need such big arrays for regression testing. It may make sense for JMH but not for these tests I think.

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PR: https://git.openjdk.java.net/jdk/pull/6594