NUMA nodes corresponding to GPU memory currently have the same
affinity/distance as normal memory nodes. Add a third NUMA associativity
reference point enabling us to give GPU nodes more distance.
This is guest visible information, which shouldn't change under a
running guest across migration between different qemu versions, so make
the change effective only in new (pseries > 5.0) machine types.
Before, `numactl -H` output in a guest with 4 GPUs (nodes 2-5):
node distances:
node 0 1 2 3 4 5
0: 10 40 40 40 40 40
1: 40 10 40 40 40 40
2: 40 40 10 40 40 40
3: 40 40 40 10 40 40
4: 40 40 40 40 10 40
5: 40 40 40 40 40 10
After:
node distances:
node 0 1 2 3 4 5
0: 10 40 80 80 80 80
1: 40 10 80 80 80 80
2: 80 80 10 80 80 80
3: 80 80 80 10 80 80
4: 80 80 80 80 10 80
5: 80 80 80 80 80 10
These are the same distances as on the host, mirroring the change made
to host firmware in skiboot commit f845a648b8cb ("numa/associativity:
Add a new level of NUMA for GPU's").
Signed-off-by: Reza Arbab <arbab@linux.ibm.com>
Message-Id: <20200716225655.24289-1-arbab@linux.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
a6030d7e0b