Re: [PATCH v4 0/5] selftests/resctrl: Add MBM and MBA test support for AMD

[Swapnil Sapkal <swapnil.sapkal@amd.com>]

Gentle Ping

On 11-08-2026 00:18, Swapnil Sapkal wrote:
> The MBM (Memory Bandwidth Monitoring) and MBA (Memory Bandwidth
> Allocation) resctrl selftests validate the bandwidth numbers reported by
> resctrl against the memory controller performance counters. Today this
> only works on Intel, where the counters are the iMC (Integrated Memory
> Controller) PMUs and the tests are gated behind an ARCH_INTEL vendor
> check.
> 
> This series teaches the tests about the AMD UMC (Unified Memory
> Controller) PMUs and enables MBM and MBA on AMD.
> 
> The work is done in a few steps:
> 
>    1. Rename the Intel specific imc/IMC identifiers to the generic
>       mc/MC so the code can serve both vendors.
> 
>    2. Detect the vendor and select the memory controller PMU sysfs name
>       accordingly, keeping the rest of the code generic.
> 
>    3. Add the AMD UMC support. Unlike Intel, the UMC PMU does not expose
>       the CAS command events via sysfs, so the read event is programmed
>       directly (EventCode 0x0a, umask 0x1). All vendor detection is
>       contained in num_of_mem_controllers() and dispatched to per-vendor
>       routines. On AMD each UMC is a per-NUMA-node PMU, so only the UMCs
>       local to the benchmark CPU are opened; remote-node UMCs would
>       otherwise fail perf_event_open() with -ENODEV.
> 
>    4. Sweep the AMD MBA schemata using absolute bandwidth values (4 GB/s
>       to 40 GB/s) instead of the Intel style percentages (10% to 100%).
> 
>    5. Extend the vendor_specific gate of the tests to Intel and AMD so
>       they run on AMD as well. The gate is kept (rather than removed)
>       so vendors that num_of_mem_controllers() does not know about are
>       skipped instead of reported as a failure.
> 
> Testing
> -------
> Tested on AMD Zen4 and Zen5 (multi-NUMA) system
> 
> History
> -------
> This series continues the work Babu Moger started; v1-v3 were posted by
> Babu. I have taken it over, rebased it onto v7.2-rc7, addressed
> Reinette's review feedback and added the AMD MBA bandwidth-value patch.
> 
> v3: https://lore.kernel.org/all/cover.1718385426.git.babu.moger@amd.com/
> 
> Changes since v3 (per patch changelog is present in each patch):
> - Rebased onto v7.2-rc7 and reworked for the upstream resctrl_val.c
>    refactor.
> - Contained all vendor detection in num_of_mem_controllers() with a
>    shared helper for the common counter "type" read. (Reinette)
> - Fixed remaining Intel specific naming and the ksft diagnostics.
>    (Reinette)
> - Handled the AMD per-node UMC PMU topology (skip remote-node UMCs) to
>    fix perf_event_open() -ENODEV on multi-node systems.
> - New patch: use absolute bandwidth values for the AMD MBA schemata,
>    with build-time checks that the sweep count matches the result arrays.
> - Kept the vendor gate at Intel | AMD so unsupported vendors are skipped
>    rather than failed.
> 
> Babu Moger (4):
>    selftests/resctrl: Rename variables and functions to generic names
>    selftests/resctrl: Detect vendor to select memory controller sysfs
>      name
>    selftests/resctrl: Add support for MBM and MBA tests on AMD
>    selftests/resctrl: Enable MBM and MBA tests on AMD
> 
> Swapnil Sapkal (1):
>    selftests/resctrl: Use bandwidth values for AMD MBA schemata
> 
>   tools/testing/selftests/resctrl/mba_test.c    | 105 +++--
>   tools/testing/selftests/resctrl/mbm_test.c    |  24 +-
>   tools/testing/selftests/resctrl/resctrl.h     |   4 +-
>   tools/testing/selftests/resctrl/resctrl_val.c | 366 +++++++++++-------
>   4 files changed, 320 insertions(+), 179 deletions(-)
>