fix syncbn parameter order mismatch and parrots bug (#488)

mmcv/ops/csrc/pytorch/pybind.cpp

@@ -121,9 +121,9 @@ void sync_bn_forward_mean(const Tensor input, Tensor mean);
 void sync_bn_forward_var(const Tensor input, const Tensor mean, Tensor var);
 
 void sync_bn_forward_output(const Tensor input, const Tensor mean,
-                            const Tensor var, Tensor running_mean,
-                            Tensor running_var, const Tensor weight,
-                            const Tensor bias, Tensor norm, Tensor std,
+                            const Tensor var, const Tensor weight,
+                            const Tensor bias, Tensor running_mean,
+                            Tensor running_var, Tensor norm, Tensor std,
                             Tensor output, float eps, float momentum,
                             int group_size);
 
@@ -299,9 +299,9 @@ PYBIND11_MODULE(TORCH_EXTENSION_NAME, m) {
         py::arg("input"), py::arg("mean"), py::arg("var"));
   m.def("sync_bn_forward_output", &sync_bn_forward_output,
         "sync_bn forward_output", py::arg("input"), py::arg("mean"),
-        py::arg("var"), py::arg("running_mean"), py::arg("running_var"),
-        py::arg("weight"), py::arg("bias"), py::arg("norm"), py::arg("std"),
-        py::arg("output"), py::arg("eps"), py::arg("momentum"),
+        py::arg("var"), py::arg("weight"), py::arg("bias"),
+        py::arg("running_mean"), py::arg("running_var"), py::arg("norm"),
+        py::arg("std"), py::arg("output"), py::arg("eps"), py::arg("momentum"),
         py::arg("group_size"));
   m.def("sync_bn_backward_param", &sync_bn_backward_param,
         "sync_bn backward_param", py::arg("grad_output"), py::arg("norm"),

mmcv/ops/csrc/pytorch/sync_bn.cpp

@@ -89,9 +89,9 @@ void sync_bn_forward_var(const Tensor input, const Tensor mean, Tensor var) {
 }
 
 void sync_bn_forward_output(const Tensor input, const Tensor mean,
-                            const Tensor var, Tensor running_mean,
-                            Tensor running_var, const Tensor weight,
-                            const Tensor bias, Tensor norm, Tensor std,
+                            const Tensor var, const Tensor weight,
+                            const Tensor bias, Tensor running_mean,
+                            Tensor running_var, Tensor norm, Tensor std,
                             Tensor output, float eps, float momentum,
                             int group_size) {
   if (input.device().is_cuda()) {
@@ -99,10 +99,10 @@ void sync_bn_forward_output(const Tensor input, const Tensor mean,
     CHECK_CUDA_INPUT(input);
     CHECK_CUDA_INPUT(mean);
     CHECK_CUDA_INPUT(var);
-    CHECK_CUDA_INPUT(running_mean);
-    CHECK_CUDA_INPUT(running_var);
     CHECK_CUDA_INPUT(weight);
     CHECK_CUDA_INPUT(bias);
+    CHECK_CUDA_INPUT(running_mean);
+    CHECK_CUDA_INPUT(running_var);
     CHECK_CUDA_INPUT(norm);
     CHECK_CUDA_INPUT(std);
     CHECK_CUDA_INPUT(output);

mmcv/ops/sync_bn.py

@@ -52,14 +52,10 @@ class SyncBatchNormFunction(Function):
             input3d.size(1), dtype=torch.float, device=input3d.device)
         var = torch.empty(
             input3d.size(1), dtype=torch.float, device=input3d.device)
-        if input3d.requires_grad or weight.requires_grad or bias.requires_grad:
         norm = torch.empty_like(
             input3d, dtype=torch.float, device=input3d.device)
         std = torch.empty(
             input3d.size(1), dtype=torch.float, device=input3d.device)
-        else:
-            norm = torch.empty(0, dtype=torch.float, device=input3d.device)
-            std = torch.empty(0, dtype=torch.float, device=input3d.device)
 
         ext_module.sync_bn_forward_mean(input3d, mean)
         if self.group_size > 1:
@@ -73,10 +69,10 @@ class SyncBatchNormFunction(Function):
             input3d,
             mean,
             var,
-            running_mean,
-            running_var,
             weight,
             bias,
+            running_mean,
+            running_var,
             norm,
             std,
             output3d,

tests/test_ops/test_syncbn.py

@@ -21,13 +21,13 @@ class TestSyncBN(object):
         node_list = str(os.environ['SLURM_NODELIST'])
 
         node_parts = re.findall('[0-9]+', node_list)
-        host_ip = '{}.{}.{}.{}'.format(node_parts[1], node_parts[2],
-                                       node_parts[3], node_parts[4])
-        port = '12341'
-        init_method = 'tcp://{}:{}'.format(host_ip, port)
+        os.environ['MASTER_ADDR'] = (f'{node_parts[1]}.{node_parts[2]}' +
+                                     f'.{node_parts[3]}.{node_parts[4]}')
+        os.environ['MASTER_PORT'] = '12341'
+        os.environ['WORLD_SIZE'] = str(world_size)
+        os.environ['RANK'] = str(rank)
 
-        dist.init_process_group(
-            'nccl', init_method=init_method, world_size=world_size, rank=rank)
+        dist.init_process_group('nccl')
         torch.cuda.set_device(local_rank)
 
     def _test_syncbn_train(self, size=1, half=False):