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Remove NCCL_NVLS_ENABLE setting from JAX image #1708

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Merged
merged 2 commits into from
Oct 6, 2025
Merged

Remove NCCL_NVLS_ENABLE setting from JAX image #1708

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Update README
aybchan Oct 3, 2025
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Remove `NCCL_NVLS_ENABLE` setting from JAX image
aybchan Oct 3, 2025
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1 change: 0 additions & 1 deletion .github/container/Dockerfile.jax
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Expand Up @@ -97,7 +97,6 @@ ENV BUILD_DATE=${BUILD_DATE}
# The following environment variables tune performance
ENV XLA_FLAGS=""
ENV XLA_FLAGS="${XLA_FLAGS} --xla_gpu_enable_latency_hiding_scheduler=true"
ENV NCCL_NVLS_ENABLE=0

COPY --from=builder ${BUILD_PATH_JAXLIB} ${BUILD_PATH_JAXLIB}
COPY --from=builder ${SRC_PATH_JAX} ${SRC_PATH_JAX}
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4 changes: 0 additions & 4 deletions README.md
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Expand Up @@ -218,10 +218,6 @@ The [JAX image](https://github.com/NVIDIA/JAX-Toolbox/pkgs/container/jax) is emb
| --------- | ----- | ----------- |
| `--xla_gpu_enable_latency_hiding_scheduler` | `true` | allows XLA to move communication collectives to increase overlap with compute kernels |

| Environment Variable | Value | Explanation |
| -------------------- | ----- | ----------- |
| `NCCL_NVLS_ENABLE` | `0` | Disables NVLink SHARP ([1](https://docs.nvidia.com/deeplearning/nccl/user-guide/docs/env.html#nccl-nvls-enable)). Future releases will re-enable this feature. |

There are various other XLA flags users can set to improve performance. For a detailed explanation of these flags, please refer to the [GPU performance](./rosetta/docs/GPU_performance.md) doc. XLA flags can also be tuned per workload. For example, each script includes a directory [xla_flags](./rosetta/rosetta/projects/maxtext/xla_flags).

For a list of previously used XLA flags that are no longer needed, please also refer to the [GPU performance](./rosetta/docs/GPU_performance.md#previously-used-xla-flags) page.
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