NVIDIA Deep Learning NCCL Documentation
Release Notes (PDF) - v2.21.5 - Last updated April 5, 2024

NCCL Release 2.9.6

This is the NCCL 2.9.6 release notes. For previous NCCL release notes, refer to the NCCL Archives.


NCCL 2.9.6 has been tested with the following:

Key Features and Enhancements

This NCCL release includes the following key features and enhancements.
  • Added support for CUDA graphs

  • Improved performance for CollNet (SHARP)

  • Fuse PCI Gen4 switches showing a two-level hierarchy into a single level.

  • Improve NIC balancing for communicators using a single GPU per node.

Fixed Issues

The following issues have been resolved in NCCL 2.9.6:
  • Fixed bootstrap hang in case of reordered packets causing connections to be inverted.

  • Fix locking issue causing NCCL calls to block until previous operations were complete.