scx_utils: expose possible and online cpus from Topology

[evanrittenhouse]

This exposes possible and online CPUs to schedulers.

Related to #721.

[htejun]

Given that topology.span is the online CPUs, it's rather odd to add separate online mask. Maybe just add topology.span_possible?

[evanrittenhouse]

Given that topology.span is the online CPUs, it's rather odd to add separate online mask. Maybe just add topology.span_possible?

Ah, I had this in draft as I was still exploring, sorry about that! Does it make sense to move the span = cpus_online() call into instantiate, like here?

[htejun]

Given that topology.span is the online CPUs, it's rather odd to add separate online mask. Maybe just add topology.span_possible?

Ah, I had this in draft as I was still exploring, sorry about that! Does it make sense to move the span = cpus_online() call into instantiate, like here?

Hmm.. are there reasons it can't be done in new()? instantiate() is there to post process the collected topology information. I don't know why online / possible cpumasks would need to be processed there.

[evanrittenhouse]

Given that topology.span is the online CPUs, it's rather odd to add separate online mask. Maybe just add topology.span_possible?

Ah, I had this in draft as I was still exploring, sorry about that! Does it make sense to move the span = cpus_online() call into instantiate, like here?

Hmm.. are there reasons it can't be done in new()? instantiate() is there to post process the collected topology information. I don't know why online / possible cpumasks would need to be processed there.

Sure thing. I still need to figure out how to integrate the possible cpumasks into the schedulers, though maybe that could/should be a followup