RFR: 8272783: Epsilon: Refactor tests to improve performance

[Thomas Schatzl]

On Fri, 20 Aug 2021 15:31:05 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Epsilon tests run in tier1, and they take considerable time, especially on low-core machines. We can refactor and simplify some of the tests for better performance.
> 
> The improvements are:
>   - Dropping test heap sizes to 64M..256M, which saves time zeroing/zapping the heap area;
>   - Dropping some configurations, notably out-of-box `-Xbatch -Xcomp` (which makes little sense, as C1/C2 paths would be taken by other configs)
> 
> Additionally, run configurations were reformatted to avoid long lines.
> 
> 
> $ make run-test TEST=gc/epsilon
> 
> # Before
> real	1m28.297s
> user	9m2.689s
> sys	0m18.370s
> 
> # After
> real	1m0.396s
> user	6m27.221s
> sys	0m13.499s

Lgtm.

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

Marked as reviewed by tschatzl (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5202