RFR: 8359104: gc/TestAlwaysPreTouchBehavior.java#<gcname> fails on Linux [v3]

[Andreas Steiner]

> 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.

Andreas Steiner has updated the pull request incrementally with one additional commit since the last revision:

  Changed num_found and num_values to size_t, do the null-check right after the fopen and return early, eliminated the variable shadowing of info

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27192/files
  - new: https://git.openjdk.org/jdk/pull/27192/files/97d88b64..6c6fc40e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27192&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27192&range=01-02

  Stats: 27 lines in 1 file changed: 5 ins; 3 del; 19 mod
  Patch: https://git.openjdk.org/jdk/pull/27192.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27192/head:pull/27192

PR: https://git.openjdk.org/jdk/pull/27192