RFR: 8335167: Test runtime/Thread/TestAlwaysPreTouchStacks.java failed with Expected a higher ratio between stack committed and reserved [v4]

[Gerard Ziemski]

On Fri, 13 Sep 2024 08:36:21 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> The test program runs once with PreTouch and another without PreTouch stacks. For each run the amounts of reserved and committed stack regions are held and then compared the ratio of with and without PreTouch. The ratio of PreTouch test should be greater than the other (because there will be higher committed regions due to pre-touching the pages).
>> 
>> In other words, the old version of this test ran two tests: 1) `preTouchTest` and 2) `noPreTouchTest` and extracted the amount of reserved and committed memory for stack. The ratio of the committed to reserved for preTouchTest ($ratio = \frac{committed}{reserved}$) is expected to be high (>75%) and for the noPreTouchTest is expected to be small (<50%). These expected amounts are not robust for all cases and resulted in 8335167.
>> 
>> In this PR, only one test is run with two sets of options for preTouch and noPreTouch stack memory. The amount of reserved and committed are stored after each run and the ratio of two runs are compared. It is expected that the preTouch has a greater ratio than the noPreTouch (`preTouch.ratio > noPreTouch.ratio`). 
>> 
>> ### Tests
>> The specific test is run on linux-x64, windows-x64 and macosx-aarch64 in tiers1-5 (100+ times).
>
> Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fixed the place of calling reportDiagnosticSummary

LGTM

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

Marked as reviewed by gziemski (Committer).

PR Review: https://git.openjdk.org/jdk/pull/20531#pullrequestreview-2310678086