Multi-GPU
Check
nvidia-smi topo -m
Result for 8 x RTX4090
GPU0 GPU1 GPU2 GPU3 GPU4 GPU5 GPU6 GPU7 CPU Affinity NUMA Affinity GPU NUMA ID
GPU0 X SYS SYS SYS SYS SYS SYS SYS 48-63,176-191 3 N/A
GPU1 SYS X SYS SYS SYS SYS SYS SYS 32-47,160-175 2 N/A
GPU2 SYS SYS X SYS SYS SYS SYS SYS 16-31,144-159 1 N/A
GPU3 SYS SYS SYS X SYS SYS SYS SYS 0-15,128-143 0 N/A
GPU4 SYS SYS SYS SYS X SYS SYS SYS 112-127,240-254 7 N/A
GPU5 SYS SYS SYS SYS SYS X SYS SYS 96-111,224-239 6 N/A
GPU6 SYS SYS SYS SYS SYS SYS X SYS 80-95,208-223 5 N/A
GPU7 SYS SYS SYS SYS SYS SYS SYS X 64-79,192-207 4 N/A
Legend:
X = Self
SYS = Connection traversing PCIe as well as the SMP interconnect between NUMA nodes (e.g., QPI/UPI)
NODE = Connection traversing PCIe as well as the interconnect between PCIe Host Bridges within a NUMA node
PHB = Connection traversing PCIe as well as a PCIe Host Bridge (typically the CPU)
PXB = Connection traversing multiple PCIe bridges (without traversing the PCIe Host Bridge)
PIX = Connection traversing at most a single PCIe bridge
NV# = Connection traversing a bonded set of # NVLinks