Merge branch 'interleaved_bugfix' into 'main'

Small bugfix to make sure refactored code works with interleaved schedule

See merge request ADLR/megatron-lm!256

megatron/training.py

@@ -195,21 +195,23 @@ def get_model(model_provider_func):
     """Build the model."""
     args = get_args()
 
-    # Build model on cpu.
-    pre_process = mpu.is_pipeline_first_stage()
-    post_process = mpu.is_pipeline_last_stage()
-
+    # Build model.
     if mpu.get_pipeline_model_parallel_world_size() > 1 and \
        args.virtual_pipeline_model_parallel_size is not None:
         model = []
         for i in range(args.virtual_pipeline_model_parallel_size):
             mpu.set_virtual_pipeline_model_parallel_rank(i)
+            # Set pre_process and post_process only after virtual rank is set.
+            pre_process = mpu.is_pipeline_first_stage()
+            post_process = mpu.is_pipeline_last_stage()
             this_model = model_provider_func(
                 pre_process=pre_process,
                 post_process=post_process
             )
             model.append(this_model)
     else:
+        pre_process = mpu.is_pipeline_first_stage()
+        post_process = mpu.is_pipeline_last_stage()
         model = model_provider_func(
             pre_process=pre_process,
             post_process=post_process