Background ========== On x86, the resctrl allows creating up to num_rmids monitoring groups under parent control group. However, ARM64 MPAM is currently limited by the PMG (Performance Monitoring Group) count, which is typically much smaller than the theoretical RMID limit. This creates a significant scalability gap: users expecting fine-grained per-process or per-thread monitoring quickly exhaust the PMG space, even when plenty of reqPARTIDs remain available. The Narrow-PARTID feature, defined in the ARM MPAM architecture, addresses this by associating reqPARTIDs with intPARTIDs through a programmable many-to-one mapping. This allows the kernel to present more logical monitoring contexts. Design Overview =============== The implementation extends the RMID encoding to carry reqPARTID information: RMID = reqPARTID * NUM_PMG + PMG In this patchset, a monitoring group is uniquely identified by the combination of reqPARTID and PMG. The closid is represented by intPARTID, which is exactly the original PARTID. For systems with homogeneous MSCs (all supporting Narrow-PARTID), the driver exposes the full reqPARTID range directly. For heterogeneous systems where some MSCs lack Narrow-PARTID support, the driver utilizes PARTIDs beyond the intPARTID range as reqPARTIDs to expand monitoring capacity. The sole exception is when MBA MSCs lack Narrow-PARTID support, their percentage-based control mechanism prevents the use of PARTIDs as reqPARTIDs. Capacity Improvements ===================== -------------------------------------------------------------------------- The maximum | Sub-monitoring groups | System-wide number of | under a control group | monitoring groups -------------------------------------------------------------------------- Without | | reqPARTID | PMG | intPARTID * PMG -------------------------------------------------------------------------- reqPARTID | | static allocation | (reqPARTID // intPARTID) * PMG | reqPARTID * PMG -------------------------------------------------------------------------- reqPARTID | | dynamic allocation | (reqPARTID − intPARTID + 1) * PMG | reqPARTID * PMG -------------------------------------------------------------------------- Under MPAM, the number of reqPARTID is always greater than or equal to intPARTID. Dave Martin (1): arm_mpam: Set INTERNAL as needed when setting MSC controls James Morse (1): debugfs: Add helpers for creating cpumask entries in debugfs Zeng Heng (30): arm_mpam: Add intPARTID and reqPARTID support for narrow PARTID feature arm_mpam: Refactor rmid to reqPARTID/PMG mapping arm_mpam: Propagate control group config to sub-monitoring groups fs/resctrl: Add rmid_entry state helpers arm_mpam: Implement dynamic reqPARTID allocation for monitoring groups fs/resctrl: Wire up rmid expansion and reclaim functions arm64/mpam: Add mpam_sync_config() for dynamic rmid expansion fs/resctrl: Prevent rmid parsing errors by flushing limbo on umount arm_mpam: Disable reqPARTID expansion when Narrow-PARTID is unavailable arm_mpam: Add MBWU counter scaling support fs/resctrl: Fix incorrect closid propagation during monitor group reparenting arm64/mpam: Fix wd boundary check and GENMASK range in percent-mbw conversion arm64/mpam: Add HISI_HIP13 support fs/resctrl: Introduce per-resource MBM enable check fs/resctrl: Add arch-specific MBM overflow setup helpers arm64/mpam: Add selective L2 MBM overflow checking arm64/mpam: Add MBM overflow handling for HIP13 arm64/mpam: Allow zero-bit CPBM for L2 cache arm64/mpam: Adapt SMMU IOMMU interface for Narrow PARTID support arm64/mpam: Add MBOPT (Memory Bandwidth Optimal) feature resctrl: Remove unused mbm_core field from rdt_domain fs/resctrl: Introduce resctrl_arch_mbm_update() for arch-specific MBM event handling arm64/mpam: Add MBM_TOTAL_EVENT configurability check arm64/mpam: Add debugfs entries to show the MSC/RIS the driver discovered iommu/arm-smmu-v3: Add debug logging for MPAM STE configuration Revert "fs/resctrl: Re-allocate rmid for the monitor when migrating across control groups" fs/resctrl: Fix iommu_group and kobject reference leaks arm_mpam: Fix NULL pointer dereference after freeing comp->cfg arm_mpam: Wait for SRCU grace period before destroying RIS arm_mpam: Fix percpu memory leak in __setup_ppi() error path arch/arm64/include/asm/mpam.h | 17 +- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 + drivers/platform/mpam/mpam_devices.c | 271 ++++++++- drivers/platform/mpam/mpam_internal.h | 21 +- drivers/platform/mpam/mpam_resctrl.c | 617 ++++++++++++++++---- fs/debugfs/file.c | 64 ++ fs/resctrl/internal.h | 1 - fs/resctrl/monitor.c | 123 ++-- fs/resctrl/rdtgroup.c | 132 +++-- include/linux/arm_mpam.h | 20 +- include/linux/debugfs.h | 6 + include/linux/resctrl.h | 35 +- include/linux/resctrl_types.h | 2 + 13 files changed, 1031 insertions(+), 281 deletions(-) -- 2.43.0