RCCL 2.21.5 for ROCm 6.3.0

Added

• MSCCL++ integration for specific contexts
• Performance collection to rccl_replayer
• Tuner Plugin example for MI300
• Tuning table for large number of nodes
• Support for amdclang++
• New Rome model

Changed

• Compatibility with NCCL 2.21.5
• Increased channel count for MI300X multi-node
• Enabled MSCCL for single-process multi-threaded contexts
• Enabled gfx12
• Enabled CPX mode for MI300X
• Enabled tracing with rocprof
• Improved version reporting
• Enabled GDRDMA for Linux kernel 6.4.0+

Resolved issues

• Fixed model matching with PXN enable

Known issues

• MSCCL is temporarily disabled for AllGather collectives.
  • This can impact in-place messages (< 2 MB) with ~2x latency.
  • Older RCCL versions are not impacted.
  • This issue will be addressed in a future ROCm release.
• Unit tests do not exit gracefully when running on a single GPU.
  • This issue will be addressed in a future ROCm release.