NVSwitch可以理解为卡与卡的集线器,能够提升卡与卡间的交互带宽,上面我们提到了NVLink有多个通道,但是这些通道并不是说都用来做两卡之间的连接, 这些通道需要搭建具体的topo结构,当机器中超过2张卡时,同一时刻卡与卡之间的带宽就不可能达到NVLink全部带宽。 NVSwitch的作用是让单GPU的NVLink带宽能力全部释放出来,比如...
The four-GPU configuration (HGX A100 4-GPU) is fully interconnected with NVIDIA NVLink, and the eight-GPU configuration (HGX A100 8-GPU) is interconnected with NVSwitch. Two NVIDIA HGX A100 8-GPU baseboards can also be combined using an NVSwitch interconnect to create a powerful 16-GPU ...
So Therefore, nccl average is limited to PCI speed and who use a nccl bandwidth higher than a PCI speed take a other communicating method like a NVlink or something. right? Member sjeaugey commented May 15, 2023 AMD CPUs don't have a PCI switch, they are connecting PCI devices, so ...
But there’s no errors in the FM logs, it just declares Dumping all the detected NVLink connections 1166 [Oct 29 2021 16:51:45] [INFO] [tid 139758] Total number of NVLink connections:0 Our nvidia-smi topo for comparison to the above guide: $ nvidia-smi topo -m GPU0 GPU1 GPU...
enable env var below in your job # ENV NCCL_TOPO_FILE="/opt/microsoft/ndv4-topo.xml" # adjusts the level of info from NCCL tests ENV NCCL_DEBUG="INFO" ENV NCCL_DEBUG_SUBSYS="GRAPH,INIT,ENV" # Relaxed Ordering can greatly help the performance of Infiniband networks in virtualized enviro...