Remove curriculum learning error when duration less than saved timest…

…amp (#1406)

Co-authored-by: Saaketh Narayan <[email protected]>

llmfoundry/callbacks/curriculum_learning_callback.py

@@ -128,18 +128,17 @@ def after_load(self, state: State, logger: Logger):
         self._validate_dataloader(state.train_dataloader)
 
         # If checkpoint was saved before iteration was incremented, we need to increment it now
+        duration = self._schedule[self._schedule_index]['duration']
         if ((
-            self._schedule[self._schedule_index]['duration'].unit
-            == TimeUnit.TOKEN and state.timestamp.token_in_iteration >=
-            self._schedule[self._schedule_index]['duration'].value
+            duration.unit == TimeUnit.TOKEN and
+            state.timestamp.token_in_iteration >= duration.value
         ) or (
-            self._schedule[self._schedule_index]['duration'].unit
-            == TimeUnit.EPOCH and state.timestamp.epoch_in_iteration >=
-            self._schedule[self._schedule_index]['duration'].value
+            duration.unit == TimeUnit.EPOCH and
+            state.timestamp.epoch_in_iteration >= duration.value
         )):
             log.warning((
-                'The CurriculumLearning callback has detected that the previous run did not correctly '
-                'increment the iteration.'
+                'The CurriculumLearning callback has detected that the '
+                'previous run did not correctly increment the iteration.'
             ))
             self._schedule_index += 1
             state.timestamp = state.timestamp.to_next_iteration()
@@ -199,24 +198,13 @@ def load_state_dict(self, state: dict[str, Any]):
                 f'Expected {saved_loader} but got {current_loader}',
             ))
 
-        # Ensure that the current datamix duration is greater than timestamp
+        # Ensure that the current datamix duration is in the correct units
         duration = self._schedule[self._schedule_index]['duration']
         if duration.unit != TimeUnit.TOKEN and duration.unit != TimeUnit.EPOCH:
             raise ValueError((
                 f'Duration must be in terms of tokens or epochs, but got ',
                 f'{duration.unit}.',
             ))
-        if ((
-            duration.unit == TimeUnit.TOKEN and
-            duration > state['timestamp'].token_in_iteration
-        ) or (
-            duration.unit == TimeUnit.EPOCH and
-            duration > state['timestamp'].epoch_in_iteration
-        )):
-            raise ValueError((
-                'The duration of the current datamix must be less or equal to '
-                'than the saved timestamp.'
-            ))
 
     def _build_train_loader(
         self,