RFR: 8315923: pretouch_memory by atomic-add-0 fragments huge pages unexpectedly [v7]

[Liming Liu]

On Wed, 4 Oct 2023 14:02:43 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Liming Liu 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. The pull request contains one new commit since the last revision:
>> 
>>   Make the jtreg test check the usage of THP
>
> src/hotspot/share/runtime/os.cpp line 2108:
> 
>> 2106:     // granularity, so we can touch anywhere in a page.  Touch at the
>> 2107:     // beginning of each page to simplify iteration.
>> 2108:     void* first = align_down(start, page_size);
> 
> minor nit, since you are touching this, could you make it const too? (void* const)

Touch needs a write anyway, and all related functions also do not use const here. So I would not add const for it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15781#discussion_r1366511981