[MiCS] [Bugfix] set self.save_non_zero_checkpoint=True only for first partition group

deepspeed/runtime/engine.py

@@ -727,6 +727,13 @@ def zero_optimization_partition_gradients(self):
     def zero_optimization_partition_weights(self):
         return self.zero_optimization_stage() >= ZeroStageEnum.weights
 
+    def is_first_weights_partition_group(self):
+        ret = True if self.mics_shard_size() < 0 \
+            and self.zero_optimization_partition_weights() else False
+        if self.mics_shard_size() > 0 and self.global_rank < self.mics_shard_size():
+            ret = True
+        return ret
+
     def zero_contiguous_gradients(self):
         return self._config.zero_config.contiguous_gradients
 
@@ -906,7 +913,8 @@ def _configure_checkpointing(self, dist_init_required):
         # only the first data parallel process needs to store the model checkpoint
         # if you want to use node local storage this must be done by rank 0 on each
         # node
-        self.save_non_zero_checkpoint = (rank == 0) or self.zero_optimization_partition_weights()
+        self.save_non_zero_checkpoint = (rank == 0) or (self.zero_optimization_partition_weights()
+                                                        and self.is_first_weights_partition_group())
 
         if self.zero_optimization() or self.bfloat16_enabled():
             param_rank = dist.get_rank(group=self.optimizer.dp_process_group)

tests/unit/checkpoint/test_mics_optimizer.py

@@ -64,3 +64,17 @@ def test_not_load_optimizer_state(self, tmpdir, shard_size):
     def test_load_module_only(self, tmpdir, shard_size):
         config_dict, hidden_dim, models = self._toy_model_config(shard_size)
         checkpoint_correctness_verification(config_dict, models, hidden_dim, tmpdir, load_module_only=True)
+
+    @pytest.mark.parametrize('shard_size', [1, 2, 4])
+    def test_save_checkpoint_on_first_partition_group(self, tmpdir, shard_size):
+        config_dict, _, models = self._toy_model_config(shard_size)
+        ds_engine, _, _, _ = deepspeed.initialize(config=config_dict,
+                                                  model=models[0],
+                                                  model_parameters=models[0].parameters(),
+                                                  optimizer=None)
+
+        ds_engine.save_checkpoint(tmpdir)
+        if ds_engine.global_rank < shard_size:
+            assert ds_engine.save_non_zero_checkpoint == True
+        else:
+            assert ds_engine.save_non_zero_checkpoint == False