[memory] add model data tensor moving api (#503)

tests/test_utils/test_commons.py

@@ -0,0 +1,49 @@
+from colossalai.utils.memory_tracer.model_data_memtracer import GLOBAL_MODEL_DATA_TRACER
+from colossalai.utils.memory_utils.utils import colo_model_data_tensor_move
+from colossalai.utils import free_port
+
+from colossalai.zero.sharded_param import ShardedTensor
+import colossalai
+
+import torch
+
+from functools import partial
+import torch.multiprocessing as mp
+import pytest
+
+
+def run_tensor_move(rank):
+    colossalai.launch(config={}, rank=0, world_size=1, host='localhost', port=free_port(), backend='nccl')
+
+    assert (GLOBAL_MODEL_DATA_TRACER.cuda_usage == 0)
+
+    src_t = torch.ones(2, 3).cuda()
+    GLOBAL_MODEL_DATA_TRACER.add_tensor(src_t)
+    assert (GLOBAL_MODEL_DATA_TRACER.cuda_usage == 24)
+    tgt_t = torch.zeros(2, 3)
+
+    colo_model_data_tensor_move(src_t, tgt_t)
+    assert (GLOBAL_MODEL_DATA_TRACER.cuda_usage == 0)
+    assert (torch.sum(tgt_t) == 6.0), f"{torch.sum(tgt_t.payload)} vs. 6.0"
+
+    src_t = torch.ones(2, 3)
+    tgt_t = torch.zeros(2, 3).cuda().half()
+    colo_model_data_tensor_move(src_t, tgt_t)
+    assert (GLOBAL_MODEL_DATA_TRACER.cuda_usage == 12), f"cuda usage {GLOBAL_MODEL_DATA_TRACER.cuda_usage}"
+    # the src_t has been removed
+    assert (src_t.numel() == 0)
+    assert (torch.sum(tgt_t) == 6.0), f"{torch.sum(tgt_t.payload)} vs. 6.0"
+
+    src_t = ShardedTensor(torch.ones(2, 3))
+    tgt_t = ShardedTensor(torch.zeros(2, 3).cuda().half())
+    colo_model_data_tensor_move(src_t, tgt_t)
+    assert (GLOBAL_MODEL_DATA_TRACER.cuda_usage == 24), f"cuda usage {GLOBAL_MODEL_DATA_TRACER.cuda_usage}"
+    assert (torch.sum(tgt_t.payload) == 6.0), f"{torch.sum(tgt_t.payload)} vs. 6.0"
+
+
+def test_tensor_move():
+    mp.spawn(run_tensor_move, nprocs=1)
+
+
+if __name__ == '__main__':
+    test_tensor_move()