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The MBA schemata line sets the maximum bandwidth. HARDLIM selects whether that maximum is a hard limit. It is a per-domain 0/1 value, not another percentage, so it is a separate control on the MBA resource rather than a second bandwidth percentage. MPAMF_MBW_IDR.MAX_LIM reports how the implementation encodes that limit. When the probed value is 0, this kernel treats HARDLIM as read/write. When MAX_LIM is nonzero, or the platform has no hard-limit control, the schemata line is omitted. The line follows the MSC, the same way the bandwidth line does. A cache MSC uses cache ids: MB:1=100;2=100 MB_MAXHLM:1=0;2=0 A memory-level MSC uses NUMA node ids: MB_NODE:0=100;1=100 MB_MAXHLM_NODE:0=0;1=0 Please advise if "MB_MAXHLM" on cache ids and "MB_MAXHLM_NODE" on NUMA ids meet the new naming conventions. 0 clears HARDLIM (soft limit). 1 sets HARDLIM. New groups start with the hard limit off. info/MB/schemata/MB_MAXHLM/max and info/MB/schemata/MB_MAXHLM_NODE/max are 1. The bandwidth control's max stays 100. The control directory under info/MB/schemata/ is MB_MAXHLM or MB_MAXHLM_NODE. The 6 patches are grouped as follows: 1. resctrl hard-limit control (patch 1) Parse MB_MAXHLM as a 0/1 value on the MBA resource, and initialize new groups with HARDLIM clear. 2. MPAM probe and config (patches 2-3) Read MAX_LIM from MPAMF_MBW_IDR, derive HARDLIM read/write when that encoding is 0, and keep the HARDLIM bit in mpam_config so later MBW_MAX programming does not drop it. 3. Wire the control (patch 4) Create the MAXHLM control on the MBA resource when HARDLIM is read/write, and read and write it through resctrl_arch_get_config() and resctrl_arch_update_one(). 4. Node scope and documentation (patches 5-6) On a memory-level MSC, name the control MB_MAXHLM_NODE, set the resource scope to the NUMA node, and give the hard-limit control the range 0..1. Document both schemata lines. The branch is on top CPU-less RFC V3 and resource controls RFC V2: https://github.com/fyu1/linux/commits/hlim.rfc.v1 Testing Brought up on an ARM MPAM platform whose MBA resource is a memory-level MSC. resctrl mounts, and schemata lists MB_NODE and MB_MAXHLM_NODE with NUMA node ids. Not tested on x86 beyond compilation of the resctrl changes. Fenghua Yu (6): resctrl: wire MB_MAXHLM schemata parsing and group setup arm_mpam: resctrl: probe MPAMF_MBW_IDR MAX_LIM and hardlim_rw arm_mpam: resctrl: track MBW max hard-limit in config arm_mpam: resctrl: add MAXHLM control on the MBA resource arm_mpam: Add MB_MAXHLM_NODE and Node scope Documentation: resctrl: document MB_MAXHLM for MPAM MBA Documentation/filesystems/resctrl.rst | 28 ++++ drivers/resctrl/mpam_devices.c | 67 ++++++++- drivers/resctrl/mpam_internal.h | 8 ++ drivers/resctrl/mpam_resctrl.c | 191 +++++++++++++++++++++----- fs/resctrl/ctrlmondata.c | 36 +++++ fs/resctrl/rdtgroup.c | 17 +++ include/linux/resctrl.h | 16 ++- 7 files changed, 325 insertions(+), 38 deletions(-) -- 2.53.0