[pipeline]add customized policy (#1139)

* [CLI] add CLI launcher

* Revert "[CLI] add CLI launcher"

This reverts commit df7e6506d4500af6a9220ef7fe4d3c7b1daebd4c.

* [pipeline]add customized policy

colossalai/pipeline/pipelinable.py

 import torch
 import inspect
 from colossalai.utils.model.utils import InsertPostInitMethodToModuleSubClasses
-from .utils import partition_uniform, partition_balanced, build_kwargs_for_function, build_kwargs_for_module, exec_func_with_kwargs, exec_funcs_with_kwargs, call_module
+
+from .utils import partition_uniform, partition_balanced, build_kwargs_for_function, \
+                build_kwargs_for_module, exec_func_with_kwargs, exec_funcs_with_kwargs, \
+                call_module, customized_partition
 from colossalai.nn.layer.utils import CheckpointModule
 from colossalai.tensor import ColoParameter
+from colossalai.core import global_context as gpc
+from colossalai.context import ParallelMode
 from .layer_sepc import LayerSpec
 
 
@@ -113,6 +118,8 @@ class PipelinableContext(InsertPostInitMethodToModuleSubClasses):
         Create a layer spec list and func list with execution sequence given by user.
         If exec_seq is None, we will take the module initizing order as execution order.
         """
+
+        self._exec_seq = exec_seq
         if exec_seq is None:
             # if user do not provide the model executing sequence, we use the initialization order as the executing order.
             children_name = []
@@ -138,6 +145,8 @@ class PipelinableContext(InsertPostInitMethodToModuleSubClasses):
             named_modules = dict(self._model.named_modules())
             for index, element in enumerate(exec_seq):
                 if isinstance(element, str):
+                    if element == 'SPLIT_NODE':
+                        continue
                     assert element in named_modules, f'Found invalid module name {element}, please check if you spell the module name correctly.'
 
                     # get the layer spec based on the module ID
@@ -178,8 +187,15 @@ class PipelinableContext(InsertPostInitMethodToModuleSubClasses):
                 for layer_spec in self._layer_spec_list:
                     param_counts.append(layer_spec.count_params())
                 parts = partition_balanced(param_counts, pipeline_size, num_chunks)[rank]
+            elif self._policy == "customized":
+                assert self._exec_seq is not None, f'An explicit exec_seq must be defined by user in customized policy mode.'
+                self.customized_parts = customized_partition(self._exec_seq)
+                assert len(self.customized_parts) == gpc.get_world_size(
+                    ParallelMode.PIPELINE
+                ), f'World size is {gpc.get_world_size(ParallelMode.PIPELINE)}, but the number of partions is {len(self.customized_parts)}'
+                parts = self.customized_parts[rank]
             else:
-                raise ValueError("A string partition policy should be one of ['uniform', 'balanced'].")
+                raise ValueError("A string partition policy should be one of ['uniform', 'balanced', 'customized'].")
         elif isinstance(self._policy, dict):
             parts = self._policy[rank]
         else:

colossalai/pipeline/utils.py

@@ -249,3 +249,24 @@ def call_module(module, args=None, kwargs=None):
         return module(*args_needed, *convert_kwargs_to_args)
     else:
         return module(*args_needed, **kwargs)
+
+def customized_partition(exec_seq):
+    '''
+    This function will analyze the exec_seq. In the exec_seq, users will use 'SPLIT_NODE' as an 
+    annotation to note the partition point.
+    '''
+    customized_parts = {}
+    start = 0
+    stop = 0
+    rank = 0
+    for element in exec_seq:
+        if isinstance(element, str):
+            if element == 'SPLIT_NODE':
+                customized_parts[rank] = [(start, stop)]
+                start = stop
+                rank += 1
+            else:
+                stop += 1
+    customized_parts[rank] = [(start, stop)]
+    return customized_parts
+