nccl dep + default for cuda (#2526)

python/mlx/distributed_run.py

@@ -20,6 +20,8 @@ from select import select
 from subprocess import PIPE, Popen, run
 from typing import Optional
 
+import mlx.core as mx
+
 
 @dataclass
 class Host:
@@ -437,8 +439,8 @@ def launch_nccl(parser, hosts, args, command):
     try:
         for rank in range(world_size):
             env = base_env.copy()
-            env["MLX_RANK"] = str(rank)
+            env["MLX_RANK"] = str(rank % args.repeat_hosts)
-            env["CUDA_VISIBLE_DEVICES"] = str(rank % args.nproc_per_node)
+            env["CUDA_VISIBLE_DEVICES"] = str(rank % args.repeat_hosts)
             p = Popen(command, env=env)
             procs.append(p)
 
@@ -708,7 +710,7 @@ def distributed_config():
     parser.add_argument(
         "--backend",
         choices=["ring", "mpi", "nccl"],
-        default="ring",
+        default="nccl" if mx.cuda.is_available() else "ring",
         help="Which distributed backend to configure",
     )
     parser.add_argument(
@@ -780,7 +782,7 @@ def main():
     parser.add_argument(
         "--backend",
         choices=["ring", "mpi", "nccl"],
-        default="ring",
+        default="nccl" if mx.cuda.is_available() else "ring",
         help="Which distributed backend to launch",
     )
     parser.add_argument(

python/scripts/repair_cuda.sh

@@ -6,6 +6,7 @@ auditwheel repair dist/* \
   --exclude libnvrtc* \
   --exclude libcuda* \
   --exclude libcudnn* \
+  --exclude libnccl* \
   -w wheel_tmp
 
 
@@ -17,7 +18,7 @@ rm "${repaired_wheel}"
 mlx_so="mlx/lib/libmlx.so"
 rpath=$(patchelf --print-rpath "${mlx_so}")
 base="\$ORIGIN/../../nvidia"
-rpath=$rpath:${base}/cublas/lib:${base}/cuda_nvrtc/lib:${base}/cudnn/lib
+rpath=$rpath:${base}/cublas/lib:${base}/cuda_nvrtc/lib:${base}/cudnn/lib:${base}/nccl/lib
 patchelf --force-rpath --set-rpath "$rpath" "$mlx_so"
 python ../python/scripts/repair_record.py ${mlx_so}
 

setup.py

@@ -297,6 +297,7 @@ if __name__ == "__main__":
                 "nvidia-cublas-cu12==12.9.*",
                 "nvidia-cuda-nvrtc-cu12==12.9.*",
                 "nvidia-cudnn-cu12==9.*",
+                "nvidia-nccl-cu12",
             ]
         else:
             name = "mlx-cpu"