RFR: 8339148: Add os::active_physical_processor_count() API

[Severin Gehwolf]

On Fri, 30 Aug 2024 08:16:37 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

>> src/hotspot/os/linux/os_linux.cpp line 4833:
>> 
>>> 4831: 
>>> 4832: // Return the active CPUs irrespective of the system being containerized
>>> 4833: // or not. Thus, this returns the host active cpus in a container.
>> 
>> No it doesn't! The comment for the function you call states clearly:
>> 
>> // Get the current number of available processors for this process.
>> 
>> This is not related to "physical count" at all!
>
> OK. Happy to change the name to something more suitable. The idea is to have a function that returns the "available" cpus of the node/host whether in container or not. How about `available_host_processor_count()`?

Just to be clear. It's not a goal to introduce new semantics.  What we need is an public accessible way to query this information.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20768#discussion_r1738228614