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[Issue]: NCCL hangs during AllReduce with P2P enabled on dual RTX Pro 6000's (Blackwells)

Status: Open.

#1999 In NVIDIA/nccl;

· robertjmcintyre opened on Jan 26, 2026

[Issue]: Upgrading NCCL from 2.22 to 2.24/2.29 causes significant performance regression in collective operations due to increased local memory instructions (ldl/stl).

Status: Open.

#1997 In NVIDIA/nccl;

· Shengqi-Pan opened on Jan 23, 2026

[Issue]: Segmentation fault at RAS in NCCL 2.27.7

Status: Open.

#1996 In NVIDIA/nccl;

· mmhzheng opened on Jan 23, 2026

[Roadmap]: NCCL Roadmap Q1 2026

roadmap

Status: Open.

#1995 In NVIDIA/nccl;

· gab9talavera opened on Jan 23, 2026

[Question]: How does the number thread blocks affect GIN performance

question

Status: Open.

#1994 In NVIDIA/nccl;

· BDHU opened on Jan 22, 2026

[Question]: Why does GIN require both crossNicSupported and !globalNicFused conditions?

question

Status: Open.

#1993 In NVIDIA/nccl;

· yesho-top opened on Jan 22, 2026

[Question]: Inspector Bug: Do RecordEvents recall after StopEvent? This results in a 'segfault encountered' error

Status: Open.

#1992 In NVIDIA/nccl;

· adai995995 opened on Jan 22, 2026

[Issue]: libnccl2 deb pkg does not run ldconfig.

Status: Open.

#1991 In NVIDIA/nccl;

· xkszltl opened on Jan 21, 2026

[Question]: Clarification on sigIdx parameter semantics for ncclPutSignal/ncclWaitSignal - support for multiple signal values

question

Status: Open.

#1988 In NVIDIA/nccl;

· RohitRathore1 opened on Jan 20, 2026

[Question]: NCCL_P2P_LEVEL

question

Status: Open.

#1987 In NVIDIA/nccl;

· tfcyoo opened on Jan 19, 2026

[Question]: Do NCCL collectives support CUDA Graph conditional nodes? (cudaGraphConditionalHandle + cudaGraphInstantiate failure)

question

Status: Open.

#1986 In NVIDIA/nccl;

· SriramKatta opened on Jan 18, 2026

[Question]: Any reason the <code>smem</code> requested by NCCL's kernels is based on MAX_THREADS instead of actual threads for the kernel?

question

Status: Open.

#1985 In NVIDIA/nccl;

· ngoyal2707 opened on Jan 17, 2026