FRF: 8216975 Using ForceNUMA does not disable adaptive sizing with parallel gc

Kim Barrett kim.barrett at oracle.com
Wed Feb 19 15:23:09 UTC 2020


> On Feb 19, 2020, at 3:35 AM, Ivan Walulya <ivan.walulya at oracle.com> wrote:
> 
> Hi all,
> 
> Please review a minor modification to disable adaptive sizing when ForceNuma is used with ParallelGC and UseLargePages on Linux OS.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8216975
> <https://bugs.openjdk.java.net/browse/JDK-8216975>Webrev: http://cr.openjdk.java.net/~iwalulya/8216975/00/ <http://cr.openjdk.java.net/~iwalulya/8216975/00/>
> Testing: Tier 1 - 3
> 
> 
> //Ivan

Setting UseNUMA true when Linux::libnuma_init returns false seems
unlikely to work.  The description of ForceNUMA is

    Force NUMA optimizations on single-node/UMA systems

which suggests how it's presently being used in numa_init is wrong.  I
think the current use should be removed and this conditional clause

5129       // If there's only one node (they start from 0) or if the process
5130       // is bound explicitly to a single node using membind, disable NUMA.
5131       UseNUMA = false;

should instead use

  UseNUMA = ForceNUMA



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