Form2 associativity adds a much more flexible NUMA topology layout
than what is provided by Form1. More details can be found in patch 7.
$ 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 memory add
# numactl -H
available: 5 nodes (0-4)
...
node distances:
node 0 1 2 3 4
0: 10 11 222 33 240
1: 44 10 55 66 255
2: 77 88 10 99 255
3: 101 121 132 10 230
4: 255 255 255 230 10
PAPR SCM now use the numa distance details to find the numa_node and target_node
for the device.
kvaneesh@ubuntu-guest:~$ ndctl list -N -v
[
{
"dev":"namespace0.0",
"mode":"devdax",
"map":"dev",
"size":1071644672,
"uuid":"d333d867-3f57-44c8-b386-d4d3abdc2bf2",
"raw_uuid":"915361ad-fe6a-42dd-848f-d6dc9f5af362",
"daxregion":{
"id":0,
"size":1071644672,
"devices":[
{
"chardev":"dax0.0",
"size":1071644672,
"target_node":4,
"mode":"devdax"
}
]
},
"align":2097152,
"numa_node":3
}
]
kvaneesh@ubuntu-guest:~$
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=222 -numa
dist,src=0,dst=3,val=33 -numa dist,src=0,dst=4,val=240 \
-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=230 \
-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=230 \
-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
Qemu changes can be found at
https://lore.kernel.org/qemu-devel/20210616011944.2996399-1-danielhb...@gmail.com/