RFR: 8371701: Add ability to set NUMA-affinity for threads

[Albert Mingkun Yang]

On Wed, 12 Nov 2025 10:22:39 GMT, Joel Sikström <jsikstro at openjdk.org> wrote:

> Hello,
> 
> This PR adds support for setting the affinity of threads to run on CPUs associated with specific NUMA nodes on Linux. Support for this is needed for [JDK-8371702](https://bugs.openjdk.org/browse/JDK-8371702) to improve performance in the Relocation Phase of ZGC on a NUMA machine.
> 
> Testing:
> * I've run significant performance testing locally on a NUMA machine and performed functional testing to see that the affinity is actually changed. Affinity of a thread can be inspected on Linux using `taskset -cp <tid>`.
> * Running through Oracle's tier1-2

src/hotspot/share/runtime/os.hpp line 537:

> 535: 
> 536:   // NUMA-specific interface
> 537:   static bool   numa_set_thread_affinity(Thread* thread, int node);

How to interpret the returned value? What do you suggest callers do with the return-value?

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PR Review Comment: https://git.openjdk.org/jdk/pull/28261#discussion_r2517863153