fix_group_sharded_note (#40488)

python/paddle/distributed/fleet/meta_parallel/sharding/sharding_stage3.py

@@ -912,7 +912,6 @@ def _device2cpu(trans_param, convert_dtype=False):
 
 def _cpu2device(param):
     tmp_p = param.fw_storage.cuda(DEV_ID)
-    param.fw_storage._clear()
     if tmp_p.dtype == Type.fp32.value and param2dtype[
             param.name] == Type.fp16.value:
         tmp_p = paddle.cast(tmp_p, Type.fp16.value)

python/paddle/distributed/sharding/group_sharded.py

@@ -39,19 +39,20 @@ def group_sharded_parallel(model,
                            segment_size=2**20,
                            sync_comm=False):
     """
-    Use this module to configure and wrap up the parameters of the group shared module.
+    Use group_sharded_parallel can perform group shared configuration on the model, optimizer and GradScaler. Level has three string options, 'os', 'os_g' and 'p_g_os' corresponds to three different usage scenarios: optimizer state segmentation, optimizer state + gradient segmentation, and parameter + gradient + optimizer state segmentation.
+    Usually, optimizer state + gradient segmentation is actually a re optimization of optimizer state segmentation, so optimizer state + gradient segmentation can be used to realize optimizer state segmentation.
 
     Args:
         model (Layer): The layer to be wrapped with group_sharded_parallel.
         optimizer (Optimizer): The optimizer to be wrapped with group_sharded_parallel.
         level (str): The different level of the group sharded. Such as `os`, `os_g`, `p_g_os`.
-        scaler (GradScaler, optional): The scaler to be wrapped with group_sharded_parallel. Defaults to None.
-        group (Group, optional): The group instance. Defaults to None.d
-        offload (bool, optional): Whether to perform optimizer state and gradient transfer CPU. Defaults to False.
-        sync_buffers (bool, optional): Whether to broadcast model buffers. Defaults to False.
-        buffer_max_size (int, optional): The max size of the buffer used to integrate gradient in `os_g`. Defaults to 2**23.
-        segment_size (int, optional): The smallest size of parameter to be sharded in `p_g_os`. Defaults to 2**20.
-        sync_comm (bool, optional): Whether to use synchronous communication, only in `p_g_os` used. Defaults to False.
+        scaler (GradScaler, optional): If AMP is used, you need to pass GradScaler. Defaults to None, indicating that GradScaler is not used.
+        group (Group, optional): The group instance. Defaults to None, indicating that the default environment group is used.
+        offload (bool, optional): Whether to use the offload function. Defaults to False, which means that the offload function is not used.
+        sync_buffers (bool, optional): Whether to broadcast model buffers. It is generally used when there are registered model buffers. Defaults to False, indicating that model buffers are not used.
+        buffer_max_size (int, optional): The max size of the buffer used to integrate gradient in `os_g`. The larger the size, the more GPU memory will be used. Defaults to 2**23, which means that the dimension of the buffer is 2**23.
+        segment_size (int, optional): The smallest size of parameter to be sharded in `p_g_os`. Defaults to 2**20, indicating that the dimension of the minimum segmented parameter is 2**20.
+        sync_comm (bool, optional): Whether to use synchronous communication, only in `p_g_os` used. Defaults to False, indicating that asynchronous communication is used.
     
     Returns:
         model: A wrapper for group sharded given model.
@@ -101,7 +102,7 @@ def group_sharded_parallel(model,
     def check_dtype(param):
         return param.dtype == paddle.float16
 
-    params_fp16 = filter(check_dtype, model.parameters())
+    params_fp16 = list(filter(check_dtype, model.parameters()))
     if scaler is None and len(params_fp16) > 0:
         raise ValueError("Please enter the correct scaler.")
     # convert model/optimizer/scaler
@@ -146,10 +147,13 @@ def save_group_sharded_model(model, output, optimizer=None):
     """
     Group sharded encapsulated model and optimizer state saving module.
 
+    .. note::
+        If using save_group_sharded_model saves the model. When loading again, you need to set the model or optimizer state before using group_sharded_parallel.
+
     Args:
         model (Layer): A wrapper for group sharded given model.
         output (str): Save directory.
-        optimizer (Optimizer, optional): Group sharded encapsulated optimizer. Defaults to None.
+        optimizer (Optimizer, optional): Group sharded encapsulated optimizer. Defaults to None, indicating that the optimizer state is not saved.
     
     Examples:
         .. code-block:: python
@@ -182,7 +186,7 @@ def save_group_sharded_model(model, output, optimizer=None):
             optimizer.clear_grad()
 
             # save model and optimizer state_dict
-            save_group_sharded_model(model, optimizer，output=output_dir)
+            save_group_sharded_model(model, optimizer, output=output_dir)
     """
     logger_.info(
         "==========Begin to save group sharded model and optimizer==========")