RFR: 8359104: gc/TestAlwaysPreTouchBehavior.java#<gcname> fails on Linux

[Matthias Baesken]

On Wed, 10 Sep 2025 13:55:59 GMT, Andreas Steiner <asteiner at openjdk.org> wrote:

> Get accurate RSS, from smaps_rollup if available(Linux >= 4.14), because the RSS from status is inaccurate especially on systems with more than 32 CPUs.
> 
> Not sure if all the additional meminfos like the Pss, Pss_dirty, Pss_Anon, Pss_File, Pss_Shmem, Swap and SwapPss are really needed too. But can be perhaps helpful too.
> 
> As the inaccurate memory infos are still used in other methods:
> - [print_process_memory_info()](https://github.com/openjdk/jdk/blob/385c13298932f1de16e6161652be35d966d822ec/src/hotspot/os/linux/os_linux.cpp#L2393)
> - [jfr_report_memory_info()](https://github.com/openjdk/jdk/blob/385c13298932f1de16e6161652be35d966d822ec/src/hotspot/os/linux/os_linux.cpp#L2686)
> - [trim_native_heap()](https://github.com/openjdk/jdk/blob/385c13298932f1de16e6161652be35d966d822ec/src/hotspot/os/linux/os_linux.cpp#L5376)
> 
> one can think about to use the accurate values there too.

we use  `size = info.rss * K;`   for the calculation in `os::rss()`  .
But   `os::Linux::query_accurate_process_memory_info  ` returns true  just in case the file could be opened , probably should we better check in a more detailed way e.g. at least that rss was found in /proc ?

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PR Comment: https://git.openjdk.org/jdk/pull/27192#issuecomment-3275309554