[pipeline] 1f1b schedule receive microbatch size (#4589)

colossalai/pipeline/schedule/one_f_one_b.py

@@ -17,14 +17,26 @@ from .base import PipelineSchedule
 
 class OneForwardOneBackwardSchedule(PipelineSchedule):
 
-    def __init__(self, num_microbatches: int, stage_manager: PipelineStageManager) -> None:
+    def __init__(self,
+                 stage_manager: PipelineStageManager,
+                 num_microbatches: Optional[int] = None,
+                 microbatch_size: Optional[int] = None) -> None:
+        """1F1B pipeline schedule.
+
+        Args:
+            stage_manager (PipelineStageManager): Pipeline stage manager
+            num_microbatches (Optional[int], optional): The number of microbatches. If not provided, it will be derived from microbatch size. Defaults to None.
+            microbatch_size (Optional[int], optional): Microbatch size. If num_microbatches is provided, this will be ignored. Defaults to None.
+        """
         super().__init__(stage_manager)
+        assert num_microbatches is not None or microbatch_size is not None, \
+            "Either num_microbatches or microbatch_size should be provided"
         self.comm = PipelineP2PCommunication(stage_manager)
         self.num_microbatches = num_microbatches
+        self.microbatch_size = microbatch_size
         self.batch: Optional[Any] = None
         self.batch_size: Optional[int] = None
         self.microbatch_offset: Optional[int] = None
-        self.microbatch_size: Optional[int] = None
 
     def load_batch(self, data_iter: Iterable, device: Optional[torch.device] = None) -> None:
         """Load a batch from data iterator.
@@ -39,9 +51,14 @@ class OneForwardOneBackwardSchedule(PipelineSchedule):
         self.batch = batch
         self.batch_size = get_batch_size(batch)
         self.microbatch_offset = 0
-        assert self.batch_size % self.num_microbatches == 0, \
-            "Batch size should divided by the number of microbatches"
-        self.microbatch_size = self.batch_size // self.num_microbatches
+        if self.num_microbatches is not None:
+            assert self.batch_size % self.num_microbatches == 0, \
+                "Batch size should divided by the number of microbatches"
+            self.microbatch_size = self.batch_size // self.num_microbatches
+        else:
+            assert self.batch_size % self.microbatch_size == 0, \
+                "Batch size should divided by the microbatch size"
+            self.num_microbatches = self.batch_size // self.microbatch_size
 
     def load_micro_batch(self) -> Any:
         """Load a micro batch from the current batch.