Re: [PATCH v3 29/47] arm_mpam: resctrl: Pick classes for use as mbm counters

Peter Newman
2026-01-15T15:49:33Z

Hi Ben,

On Mon, Jan 12, 2026 at 6:02 PM Ben Horgan <ben.horgan@arm.com> wrote:
>
> From: James Morse <james.morse@arm.com>
>
> resctrl has two types of counters, NUMA-local and global. MPAM has only
> bandwidth counters, but the position of the MSC may mean it counts
> NUMA-local, or global traffic.
>
> But the topology information is not available.
>
> Apply a heuristic: the L2 or L3 supports bandwidth monitors, these are
> probably NUMA-local. If the memory controller supports bandwidth monitors,
> they are probably global.

Are remote memory accesses not cached? How do we know an MBWU monitor
residing on a cache won't count remote traffic?

Thanks,
-Peter