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

[Albert Mingkun Yang]

On Wed, 12 Nov 2025 11:11:57 GMT, Joel Sikström <jsikstro at openjdk.org> wrote:

>> 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?
>
> I'm seeing the return value as "was this operation successful or not". I could add a comment in the header file with something like the following if you think it would make things clearer.
> 
> // Sets the affinity of a thread to the CPUs associated with a NUMA node. Passing node
> // as -1 sets the affinity to all CPUs the JVM is allowed to run on. Returns true if
> // the thread's affinity has been changed, false otherwise.

This interpretation makes sense, but what should callers do with the `false` case?

(In #28262, the return-value is just ignored, isn't it?)

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PR Review Comment: https://git.openjdk.org/jdk/pull/28261#discussion_r2518249758