RFR: 8315923: pretouch_memory by atomic-add-0 fragments huge pages unexpectedly [v28]

[Liming Liu]

On Fri, 19 Jan 2024 09:38:56 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Liming Liu has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Untabify
>
> src/hotspot/os/linux/os_linux.cpp line 4403:
> 
>> 4401:   // Check the availability of MADV_POPULATE_WRITE.
>> 4402:   UseMadvPopulateWrite = (::madvise(0, 0, MADV_POPULATE_WRITE) == 0);
>> 4403: 
> 
> What happens if the user sets `UseMadvPopulateWrite` to false when starting the JVM? It should not be used then.

It is before Arguments::parse, so I would use FLAG_SET_DEFAULT here.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15781#discussion_r1461306428