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To me it seems >>>>>> to be >>>>>> accidental that it maps to the NUMA node but really the scope is just a grouping of L3 instances. >>>>>> For a control to NUMA scope I would expect the resctrl domains to go offline and online in sync >>>>>> with >>>>>> the NUMA nodes. For GMBA it looks like it would just going offline/online based on whether any of >>>>>> the CPUs and so L3 instances in the group are online. Am I correct here? >>>>>> >>>>>> Assuming the domains are on L3 groups rather than NUMA also changes which end of the link the >>>>>> traffic is regulated and so how cross-NUMA traffic behaves differently. If the domain is an L3 >>>>>> group >>>>>> then a task running on a CPU affine to that L3 group won't be throttled unless that particular >>>>>> domain is throttled but with NUMA node domains it may be throttled if it has traffic going to that >>>>>> domain. >>>>> >>>>> I'll defer to Babu for accurate answers about this hardware capability. >>>>> >>>> >>>> To me, Global MBA should be considered a NODE-scoped resource. In some configurations it may appear >>>> as SYSTEM-scoped, but that is effectively equivalent to a single-node encompassing the entire >>>> system. In such cases, there is only one schemata entry controlling the whole system. >>>> >>>> Yes, multiple L3 instances are grouped together to form a NODE. Internally, programming is still >>>> performed at the L3 level, but that implementation detail can be hidden from users and does not need >>>> to be exposed through the interface. >>> >>> We seem to have two things that can both, somewhat reasonably, be called NODE scope in the resctrl >>> user interface but the behaviour required for an MPAM system and an AMD system appears different >>> from the point of view of lifecycle of the resctrl domain. >>> >>> For MPAM NUMA scope the MSC instance (MPAM hardware interface) is at the memory controller and so >>> goes on and offline based on whether the NUMA node is offline or online. For AMD NUMA scope it looks >>> to me that the lifecycle of the resctrl domains would be tied to the CPUs associated with the NUMA >>> node. To me it does seem odd that a control with a domain associated with an offline NUMA node can >>> continue to throttle (cross-NUMA) traffic. >>> >>> Is there any GLBE Control Domain ID or similar that is exposed to the user, e.g. is sysfs, or is >>> this just implicitly the NUMA id? >>> >> Yes, the GLBE Control Domain ID is exposed to the user. It is essentially equivalent to the NUMA ID. > > What's the on/off lifecycle of these nodes? Does it follow the NUMA lifecycle as managed by the NUMA > node notifiers documented in Documentation/core-api/memory-hotplug.rst or is it just linked to the > cpu hotplug as is done currently for the resctrl cache based domains. > It will follow the CPU hotplug lifecycle, similar to how it is currently handled for the resctrl cache-based domains. Thanks, Babu