Integrated: 8333769: Pretouching tests dont test pretouching

[Sonia Zaldana Calles]

On Thu, 13 Jun 2024 13:24:42 GMT, Sonia Zaldana Calles <szaldana at openjdk.org> wrote:

> Hi all, 
> 
> This PR addresses [8333769](https://bugs.openjdk.org/browse/JDK-8333769).
> 
> We already have a test for  parallel GC that makes sure pretouching behaviour is correct ([test/hotspot/jtreg/gc/parallel/TestAlwaysPreTouchBehavior.java](https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/gc/parallel/TestAlwaysPreTouchBehavior.java)). 
> 
> Unfortunately this test is limited to linux because of the scanning of `/proc/pid/status`. With this patch I propose two changes: 
> 
> - Adding a function to the os namespace `os::rss` and exposing this API via WhiteBox. This in turn allows us to generalize the above test to be used across all platforms. 
> - Running the modified test with all collectors. 
> 
> Additionally, I considered removing other pre-existing pretouch tests (for example, this [z test](https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/gc/z/TestAlwaysPreTouch.java)), as this new test is a bit more thorough. However, I noticed that some of these tests run alongside other configurables such as varying numbers of parallel GC threads, varying heap sizes, etc. Therefore, there might not be any harm in running these tests as well. 
> 
> Looking forward to your comments, 
> Sonia

This pull request has now been integrated.

Changeset: 8bc2fbe5
Author:    Sonia Zaldana Calles <szaldana at openjdk.org>
Committer: Thomas Stuefe <stuefe at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/8bc2fbe57893b110fdb5fd567df4615e7833e5ae
Stats:     257 lines in 9 files changed: 178 ins; 79 del; 0 mod

8333769: Pretouching tests dont test pretouching

Reviewed-by: stuefe, asmehra

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PR: https://git.openjdk.org/jdk/pull/19699