The Sub-NUMA cluster feature on some Intel processors partitions the CPUs that share an L3 cache into two or more sets. This plays havoc with the Resource Director Technology (RDT) monitoring features. Prior to this patch Intel has advised that SNC and RDT are incompatible. Some of these CPU support an MSR that can partition the RMID counters in the same way. This allows monitoring features to be used. With the caveat that users must be aware that Linux may migrate tasks more frequently between SNC nodes than between "regular" NUMA nodes, so reading counters from all SNC nodes may be needed to get a complete picture of activity for tasks. Cache and memory bandwidth allocation features continue to operate at the scope of the L3 cache. Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx> --- Changes since v15: Link: https://lore.kernel.org/all/20240228112935.8087-tony.luck@xxxxxxxxx/ 0) Note that v14 Reviewed/Testing tags have been removed because of the extent of refactoring to catch up with upstream. But nothing fundamental changed, so everything should look familiar. 1) Refactor to apply on top of Link: https://lore.kernel.org/all/20240308213846.77075-1-tony.luck@xxxxxxxxx/ [So base commit is either tip x86/cache, or upstream current merge PLUS the two patches in that series] 2) Add patch 9 which adds files showing mappings from domains to CPUs Reinette suggested this, James thinks it duplicates information that can be gathered from /sys/devices/system/ Discussion here: Link: https://lore.kernel.org/all/ZetcM9GO2PH6SC0j@agluck-desk3/ This part is a nice-to-have. I'm fine if just the first eight patches are applied without this while the discussion continues. Tony Luck (9): x86/resctrl: Prepare for new domain scope x86/resctrl: Prepare to split rdt_domain structure x86/resctrl: Prepare for different scope for control/monitor operations x86/resctrl: Split the rdt_domain and rdt_hw_domain structures x86/resctrl: Add node-scope to the options for feature scope x86/resctrl: Introduce snc_nodes_per_l3_cache x86/resctrl: Sub NUMA Cluster detection and enable x86/resctrl: Update documentation with Sub-NUMA cluster changes x86/resctrl: Add info files to show mappings from domains to lists of cpus Documentation/arch/x86/resctrl.rst | 44 ++- include/linux/resctrl.h | 85 +++-- arch/x86/include/asm/msr-index.h | 1 + arch/x86/kernel/cpu/resctrl/internal.h | 67 ++-- arch/x86/kernel/cpu/resctrl/core.c | 428 ++++++++++++++++++---- arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 56 +-- arch/x86/kernel/cpu/resctrl/monitor.c | 70 ++-- arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 26 +- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 213 +++++++---- 9 files changed, 718 insertions(+), 272 deletions(-) -- 2.44.0
