Form2 associativity adds a much more flexible NUMA topology layout than what is provided by Form1. This also allows PAPR SCM device to use better associativity when using the device as DAX KMEM device. More details can be found in patch 7.
$ ndctl list -N -v [ { "dev":"namespace0.0", "mode":"devdax", "map":"dev", "size":1071644672, "uuid":"37dea198-ddb5-4e42-915a-99a915e24188", "raw_uuid":"148deeaa-4a2f-41d1-8d74-fd9a942d26ba", "daxregion":{ "id":0, "size":1071644672, "devices":[ { "chardev":"dax0.0", "size":1071644672, "target_node":4, "mode":"devdax" } ] }, "align":2097152, "numa_node":1 } ] $ numactl -H ... node distances: node 0 1 2 3 0: 10 11 222 33 1: 44 10 55 66 2: 77 88 10 99 3: 101 121 132 10 $ After DAX KMEM # numactl -H available: 5 nodes (0-4) ... node distances: node 0 1 2 3 4 0: 10 11 22 33 255 1: 44 10 55 66 255 2: 77 88 10 99 255 3: 101 121 132 10 255 4: 255 255 255 255 10 # The above output is with a Qemu command line -numa node,nodeid=4 \ -numa dist,src=0,dst=1,val=11 -numa dist,src=0,dst=2,val=22 -numa dist,src=0,dst=3,val=33 -numa dist,src=0,dst=4,val=255 \ -numa dist,src=1,dst=0,val=44 -numa dist,src=1,dst=2,val=55 -numa dist,src=1,dst=3,val=66 -numa dist,src=1,dst=4,val=255 \ -numa dist,src=2,dst=0,val=77 -numa dist,src=2,dst=1,val=88 -numa dist,src=2,dst=3,val=99 -numa dist,src=2,dst=4,val=255 \ -numa dist,src=3,dst=0,val=101 -numa dist,src=3,dst=1,val=121 -numa dist,src=3,dst=2,val=132 -numa dist,src=3,dst=4,val=255 \ -numa dist,src=4,dst=0,val=255 -numa dist,src=4,dst=1,val=255 -numa dist,src=4,dst=2,val=255 -numa dist,src=4,dst=3,val=255 \ -object memory-backend-file,id=memnvdimm1,prealloc=yes,mem-path=$PMEM_DISK,share=yes,size=${PMEM_SIZE} \ -device nvdimm,label-size=128K,memdev=memnvdimm1,id=nvdimm1,slot=4,uuid=72511b67-0b3b-42fd-8d1d-5be3cae8bcaa,node=4,device-node=1 Qemu changes can be found at https://lore.kernel.org/qemu-devel/20210616011944.2996399-1-danielhb...@gmail.com/ Changes from v2: * Add nvdimm list to Cc: * update PATCH 8 commit message. Changes from v1: * Update FORM2 documentation. * rename max_domain_index to max_associativity_domain_index Aneesh Kumar K.V (8): powerpc/pseries: rename min_common_depth to primary_domain_index powerpc/pseries: rename distance_ref_points_depth to max_associativity_domain_index powerpc/pseries: Rename TYPE1_AFFINITY to FORM1_AFFINITY powerpc/pseries: Consolidate DLPAR NUMA distance update powerpc/pseries: Consolidate NUMA distance update during boot powerpc/pseries: Add a helper for form1 cpu distance powerpc/pseries: Add support for FORM2 associativity powerpc/papr_scm: Use FORM2 associativity details Documentation/powerpc/associativity.rst | 177 +++++++ arch/powerpc/include/asm/firmware.h | 7 +- arch/powerpc/include/asm/prom.h | 3 +- arch/powerpc/kernel/prom_init.c | 3 +- arch/powerpc/mm/numa.c | 436 ++++++++++++++---- arch/powerpc/platforms/pseries/firmware.c | 3 +- arch/powerpc/platforms/pseries/hotplug-cpu.c | 2 + .../platforms/pseries/hotplug-memory.c | 2 + arch/powerpc/platforms/pseries/papr_scm.c | 26 +- arch/powerpc/platforms/pseries/pseries.h | 2 + 10 files changed, 560 insertions(+), 101 deletions(-) create mode 100644 Documentation/powerpc/associativity.rst -- 2.31.1