https://github.com/argonne-lcf/alcf-nccl-tests

NCCL tests for ALCF machines
https://github.com/argonne-lcf/alcf-nccl-tests

Last synced: 3 months ago
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NCCL tests for ALCF machines

• Host: GitHub
• URL: https://github.com/argonne-lcf/alcf-nccl-tests
• Owner: argonne-lcf
• Created: 2024-04-29T21:26:05.000Z (6 months ago)
• Default Branch: main
• Last Pushed: 2024-07-08T19:19:41.000Z (4 months ago)
• Last Synced: 2024-07-09T00:12:36.718Z (4 months ago)
• Language: Roff
• Size: 2.24 MB
• Stars: 4
• Watchers: 5
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Testing NCCL performance on ALCF systems

This is for performing NCCL tests with different environment setups (1)-(5) to identify the best setup for NCCL on ALCF systems. We find out that the optimal setup is

**ATTENTION** 

For PYTHON workload, one has to remove ``export NCCL_NET_GDR_LEVEL=PHB`` on Polaris, because it will cause hang. 

```bash

export NCCL_NET_GDR_LEVEL=PHB

export NCCL_CROSS_NIC=1

export NCCL_COLLNET_ENABLE=1

export NCCL_NET="AWS Libfabric"

export LD_LIBRARY_PATH=/soft/libraries/aws-ofi-nccl/v1.9.1-aws/lib:$LD_LIBRARY_PATH

export LD_LIBRARY_PATH=/soft/libraries/hwloc/lib/:$LD_LIBRARY_PATH

export FI_CXI_DISABLE_HOST_REGISTER=1

export FI_MR_CACHE_MONITOR=userfaultfd

export FI_CXI_DEFAULT_CQ_SIZE=131072

```

This achieves 5-10x improvement over the default setup. 

## Different environment setups

(1) Default settting, no NCCL environement setup. This will use TCP, resulting very bad performance. 

(2) with following setup

```bash 

export NCCL_NET_GDR_LEVEL=PHB

export NCCL_CROSS_NIC=1

export NCCL_COLLNET_ENABLE=1

```

(3) the following setup is to see how aws libfabric plugin helps

```bash

export NCCL_NET_GDR_LEVEL=PHB

export NCCL_CROSS_NIC=1

export NCCL_COLLNET_ENABLE=1

export NCCL_NET="AWS Libfabric"

export LD_LIBRARY_PATH=/soft/libraries/aws-ofi-nccl/v1.9.1-aws/lib:$LD_LIBRARY_PATH

```

Note that this will requires the AWS plugin, which can be built on Polaris

```bash 

git clone v1.9.1-aws https://github.com/aws/aws-ofi-nccl.git

cd aws-ofi-nccl

./configure --prefix=/home/hzheng/PolarisAT/soft/aws-ofi-nccl --with-libfabric=/opt/cray/libfabric/1.15.2.0/ --with-cuda=/soft/compilers/cudatoolkit/cuda\

-12.4.1 --with-hwloc=/soft/libraries/hwloc/

```

(4) the following setup is to see how FI environment variables help

```bash

export NCCL_NET_GDR_LEVEL=PHB

export NCCL_CROSS_NIC=1

export NCCL_COLLNET_ENABLE=1

export NCCL_NET="AWS Libfabric"

export LD_LIBRARY_PATH=/soft/libraries/aws-ofi-nccl/v1.9.1-aws/lib:$LD_LIBRARY_PATH

export FI_CXI_DISABLE_HOST_REGISTER=1

export FI_MR_CACHE_MONITOR=userfaultfd

export FI_CXI_DEFAULT_CQ_SIZE=131072

```

(5) The following setup is for testing alltoall 

```bash

export NCCL_NET_GDR_LEVEL=PHB

export NCCL_CROSS_NIC=1

export NCCL_COLLNET_ENABLE=1

export NCCL_NET="AWS Libfabric"

export LD_LIBRARY_PATH=/soft/libraries/aws-ofi-nccl/v1.9.1-aws/lib:$LD_LIBRARY_PATH

export FI_CXI_DISABLE_HOST_REGISTER=1

export FI_MR_CACHE_MONITOR=userfaultfd

export FI_CXI_DEFAULT_CQ_SIZE=131072

export FI_CXI_RX_MATCH_MODE=software

export FI_CXI_RDZV_PROTO=alt_read

export FI_CXI_REQ_BUF_SIZE=8388608

```

## Results & Conclusion

The results are shown in [./results_polaris](./results_polaris). One can find analysis here: [./nccl-performance-evaluation.ipynb](./nccl-performance-evaluation.ipynb)

The main conclusions are: 

* For allreduce and all_gather, the best setup is following. We achieve 5-10x improvement over the default setup. 

    ```bash

    export NCCL_NET_GDR_LEVEL=PHB

    export NCCL_CROSS_NIC=1

    export NCCL_COLLNET_ENABLE=1

    export NCCL_NET="AWS Libfabric"

    export LD_LIBRARY_PATH=/soft/libraries/aws-ofi-nccl/v1.9.1-aws/lib:$LD_LIBRARY_PATH

    export LD_LIBRARY_PATH=/soft/libraries/hwloc/lib/:$LD_LIBRARY_PATH

    export FI_CXI_DISABLE_HOST_REGISTER=1

    export FI_MR_CACHE_MONITOR=userfaultfd

    export FI_CXI_DEFAULT_CQ_SIZE=131072

    ```

* For alltoall with message size larger than 8MB, additional setup is needed. But this will influence the latency for allreduce and all_gather at smaller message size (<1MB)

    ```bash

    export FI_CXI_RX_MATCH_MODE=software

    export FI_CXI_RDZV_PROTO=alt_read

    export FI_CXI_REQ_BUF_SIZE=8388608

    ```

    

* For allreduce, Slingshot 11 with (4) setup is 3x speed up over slingshot 10 results (for message size over 10 MB)

* We were able to run up to 540 nodes with (4) and (5).

* With (1), we were not able to go beyond 128 nodes. all_gather will cause node failure.