!6781 Change prefix for server ckpt callback

Merge pull request !6781 from ZPaC/master-change-prefix-for-server-ckpt

mindspore/parallel/_ps_context.py

@@ -95,10 +95,11 @@ def _get_ps_context(attr_key):
     Raises:
         ValueError: If input key is not attribute in auto parallel context.
     """
-    if key not in _get_ps_context_func_map:
-        raise ValueError("Get PS context keyword %s is not recognized!" % key)
+    if attr_key not in _get_ps_context_func_map:
+        raise ValueError("Get PS context keyword %s is not recognized!" % attr_key)
     get_func = _get_ps_context_func_map[attr_key]
-    get_func(attr_key)
+    value = get_func()
+    return value
 
 def _reset_ps_context():
     """

mindspore/train/callback/_checkpoint.py

@@ -228,6 +228,8 @@ class ModelCheckpoint(Callback):
         Args:
             run_context (RunContext): Context of the train running.
         """
+        if _is_role_pserver():
+            self._prefix = "PServer_" + str(_get_ps_mode_rank()) + "_" + self._prefix
         cb_params = run_context.original_args()
         # save graph (only once)
         if not self._graph_saved:
@@ -281,8 +283,6 @@ class ModelCheckpoint(Callback):
         if save_ckpt:
             cur_ckpoint_file = self._prefix + "-" + str(cb_params.cur_epoch_num) + "_" \
                                + str(step_num_in_epoch) + ".ckpt"
-            if _is_role_pserver():
-                cur_ckpoint_file = "PServer_" + str(_get_ps_mode_rank()) + "_" + cur_ckpoint_file
             # update checkpoint file list.
             self._manager.update_ckpoint_filelist(self._directory, self._prefix)
             # keep checkpoint files number equal max number.