Re: [PATCH v8 06/24] x86/resctrl: Access per-rmid structures by index

Reinette Chatre
2023-12-16T04:58:41Z

Hi James,

On 12/15/2023 9:43 AM, James Morse wrote:
> x86 systems identify traffic using the CLOSID and RMID. The CLOSID is
> used to lookup the control policy, the RMID is used for monitoring. For
> x86 these are independent numbers.
> Arm's MPAM has equivalent features PARTID and PMG, where the PARTID is
> used to lookup the control policy. The PMG in contrast is a small number
> of bits that are used to subdivide PARTID when monitoring. The
> cache-occupancy monitors require the PARTID to be specified when
> monitoring.
>
> This means MPAM's PMG field is not unique. There are multiple PMG-0, one
> per allocated CLOSID/PARTID. If PMG is treated as equivalent to RMID, it
> cannot be allocated as an independent number. Bitmaps like rmid_busy_llc
> need to be sized by the number of unique entries for this resource.
>
> Treat the combined CLOSID and RMID as an index, and provide architecture
> helpers to pack and unpack an index. This makes the MPAM values unique.
> The domain's rmid_busy_llc and rmid_ptrs[] are then sized by index, as
> are domain mbm_local[] and mbm_total[].
>
> x86 can ignore the CLOSID field when packing and unpacking an index, and
> report as many indexes as RMID.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
> Tested-by: Peter Newman <peternewman@google.com>
> Tested-by: Babu Moger <babu.moger@amd.com>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
> Reviewed-by: Babu Moger <babu.moger@amd.com>
> ---

Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>

Reinette