Troubleshooting

Hints

• If any issues need to be debugged, the following environment variables are very useful:

  • CUBLASMP_LOG_LEVEL environment variable to enable detailed logging of cuBLASMp operations

  • NCCL_DEBUG. NCCL provides extensive debugging capabilities through environment variables such as NCCL_DEBUG. For a comprehensive list of NCCL debugging options, refer to the NCCL Environment Variables documentation.

Known Issues

• cuBLASMp versions older than 0.5.0: Some users may face hangs due to lazy initialization of NCCL in UCC. To disable the lazy NCCL initialization, please set UCC_TL_NCCL_LAZY_INIT environment variable to no.

• cuBLASMp versions older than 0.5.0: Some users may see errors with HPC-X v2.18 caused by a clash of UCC being initialized in OMPI and cuBLASMp. To disable UCC initialization in OMPI, please set OMPI_MCA_coll_ucc_enable environment variable to 0.