Issues

• Interest in additional tests for correctness?

  NVIDIA/nccl-tests#403 · Filter by author maxstu opened on Oct 23, 2026
  3

• Incorrect bus bandwidth factor calculation in alltoallv with distance-weighted spread

  NVIDIA/nccl-tests#400 · Filter by author levilee-lwl opened on Oct 14, 2026

• Will nccl-test support testing for NCCL EP?

  NVIDIA/nccl-tests#390 · Filter by author wanggeng09825 opened on Jul 30, 2026
  2

• 8xB200 nccl test performance validation

  NVIDIA/nccl-tests#389 · Filter by author shahizat opened on Jul 22, 2026

• Suggestion to adjust license wording for consistency with standard BSD-style phrasing

  NVIDIA/nccl-tests#385 · Filter by author wjjahah opened on May 29, 2026
  1

• Why are different buffers used for each iteration when -n > 1 in nccl-tests?

  NVIDIA/nccl-tests#384 · Filter by author lidxhaha opened on May 29, 2026
  1

• alltoall: NCCL_WIN_COLL_SYMMETRIC incorrectly triggers symk GIN init, causing AlltoAll DevComm GIN connection to be silently skipped

  NVIDIA/nccl-tests#381 · Filter by author YeSho-cpp opened on May 13, 2026
  6

• NCCL all-reduce bandwidth drops in VMs when using more than 2 passthrough ConnectX-7 NICs

  NVIDIA/nccl-tests#380 · Filter by author mjf-89 opened on Apr 30, 2026
  1

• NCCL_IB_DISABLE=1 not work

  NVIDIA/nccl-tests#373 · Filter by author haolujun opened on Feb 25, 2026
  2

• h100 only has 70GB on bus

  NVIDIA/nccl-tests#371 · Filter by author poptree opened on Feb 7, 2026
  1

• running multi-node with Exclusive Process

  NVIDIA/nccl-tests#369 · Filter by author angainor opened on Jan 21, 2026
  18

• Is it applicable to the L20 card?

  NVIDIA/nccl-tests#368 · Filter by author jiaozenghui opened on Jan 20, 2026
  4

• H20-3e 400Gx8 Roce Actual performance experimental data

  NVIDIA/nccl-tests#367 · Filter by author Rankole opened on Jan 10, 2026

• ALL_Reduce_Perf with NVLS in one node(8GPUs)

  NVIDIA/nccl-tests#366 · Filter by author networkResearcher opened on Jan 9, 2026
  1

• Segfault while running benchmarks

  NVIDIA/nccl-tests#363 · Filter by author access2rohit opened on Dec 12, 2025

• Low NCCL Performance in ubuntu kernel 6.8.x

  NVIDIA/nccl-tests#362 · Filter by author fazlan1990 opened on Dec 10, 2025
  6

• Multi-node all_reduce_perf / alltoall_perf failures: socketFinalizeAccept wrong type 4 != 3 over TCP and IB QP invalid request errors

  NVIDIA/nccl-tests#360 · Filter by author AlexanderNekrasov opened on Nov 24, 2025
  4

• Does the GinAlltoAllKernel have send/receive conflicts in in-place mode?

  NVIDIA/nccl-tests#357 · Filter by author shenhongqian opened on Oct 30, 2025
  1

• test deviceImpl And got error 'an illegal memory access was encountered'

  NVIDIA/nccl-tests#355 · Filter by author Qizhi697 opened on Oct 30, 2025
  5

• Latest Commits Causing Compile Errors for File alltoall.cu

  NVIDIA/nccl-tests#354 · Filter by author benjaminli-microsoft opened on Oct 27, 2025
  2

• can ncu profiling peer memory traffic

  NVIDIA/nccl-tests#348 · Filter by author Alice1069 opened on Oct 10, 2025

• alltoall not in generate.py

  NVIDIA/nccl-tests#344 · Filter by author woodenmen opened on Sep 10, 2025
  1

• can alltoall use zero copy (only send without recv) by ncclCommRegister?

  NVIDIA/nccl-tests#341 · Filter by author ieeechuhaoyun opened on Aug 27, 2025
  6

• Some benchmarks fail with PXN enabled

  NVIDIA/nccl-tests#340 · Filter by author MeisterEule opened on Aug 19, 2025

• UnknownError when trying to profile NCCL all reduce perf test with Nsight Compute

  NVIDIA/nccl-tests#339 · Filter by author amoghdadhich opened on Aug 17, 2025