tests/python/gpu/test_nccl.py

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import mxnet as mx
import numpy as np
import os
import pytest

shapes = [(10), (100), (1000), (10000), (100000), (2,2), (2,3,4,5,6,7,8)]
keys = [1,2,3,4,5,6,7]
num_gpus = mx.device.num_gpus()


if num_gpus > 8 :
    print("The machine has {} gpus. We will run the test on 8 gpus.".format(num_gpus))
    print("There is a limit for all PCI-E hardware on creating number of P2P peers. The limit is 8.")
    num_gpus = 8;

gpus = range(1, 1+num_gpus)

@pytest.mark.skip(reason="Test requires NCCL library installed and enabled during build")
def test_nccl_pushpull():
    for shape, key in zip(shapes, keys):
        for n_gpus in gpus:
            kv_nccl = mx.kv.create('nccl')
            a = mx.nd.ones(shape, mx.gpu(0))
            cur_key = str(key*max(gpus)+n_gpus)
            kv_nccl.init(cur_key, a)
            arr_list = [mx.nd.ones(shape, mx.gpu(x)) for x in range(n_gpus)]
            res = [mx.nd.zeros(shape, mx.gpu(x)) for x in range(n_gpus)]
            kv_nccl.push(cur_key, arr_list)
            kv_nccl.pull(cur_key, res)
            for x in range(n_gpus):
                assert(np.sum(np.abs((res[x]-n_gpus).asnumpy()))==0)

    print ("Passed")

if __name__ == '__main__':
    test_nccl_pushpull()