Re: [PATCH v5 1/5] arm_mpam: resctrl: Pick classes for use as MBM counters

[Gavin Shan]

On 7/8/26 2:24 AM, Ben Horgan wrote:
> From: James Morse <james.morse@xxxxxxx>
>
> resctrl has two types of bandwidth counters, NUMA-local and global. MPAM
> can only count globally; either using MSC at the L3 cache or in the memory
> controllers. When global and local equate to the same thing continue just
> to call it global.
>
> Pick the corresponding MPAM classes to back the MBM counters. As resctrl
> requires all monitors to be at the L3 cache, we can only use the counters
> at the memory controllers when they have the same topology as the L3 cache
> and the traffic they see if the same. In particular, for the bandwidth
> counters at the memory controllers to be exposed to resctrl it is required
> there is a single L3 cache and a single NUMA node as otherwise cross NUMA
> traffic will be counted at the wrong instance.
>
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
> Tested-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> Tested-by: Zeng Heng <zengheng4@xxxxxxxxxx>
> Tested-by: Fenghua Yu <fenghuay@xxxxxxxxxx>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
> Reviewed-by: Fenghua Yu <fenghuay@xxxxxxxxxx>
> ---
> Changes since rfc v1:
> Move finding any_mon_comp into monitor boilerplate patch
> Move mpam_resctrl_get_domain_from_cpu() into monitor boilerplate
> Remove free running check
> Trim commit message
>
> Changes since v3:
> Extra paragraph in commit message
>
> Changes since v4:
> Commit message tag ordering
> New sentence in block comment (Fenghua)
> ---
>   drivers/resctrl/mpam_resctrl.c | 28 ++++++++++++++++++++++++++++
>   1 file changed, 28 insertions(+)

Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>