[core] [3/N] multi-step args and sequence.py (#7452)

vllm/config.py

@@ -847,7 +847,8 @@ class SchedulerConfig:
                  delay_factor: float = 0.0,
                  enable_chunked_prefill: bool = False,
                  embedding_mode: Optional[bool] = False,
-                 preemption_mode: Optional[str] = None) -> None:
+                 preemption_mode: Optional[str] = None,
+                 num_scheduler_steps: int = 1) -> None:
         if max_num_batched_tokens is not None:
             self.max_num_batched_tokens = max_num_batched_tokens
         else:
@@ -876,6 +877,7 @@ class SchedulerConfig:
         self.chunked_prefill_enabled = enable_chunked_prefill
         self.embedding_mode = embedding_mode
         self.preemption_mode = preemption_mode
+        self.num_scheduler_steps = num_scheduler_steps
         self._verify_args()
 
     def _verify_args(self) -> None:
@@ -901,6 +903,16 @@ class SchedulerConfig:
                 f"({self.num_lookahead_slots}) must be greater than or "
                 "equal to 0.")
 
+        if self.num_scheduler_steps < 1:
+            raise ValueError(
+                "num_scheduler_steps "
+                f"({self.num_scheduler_steps}) must be greater than or "
+                "equal to 1.")
+
+    @property
+    def is_multi_step(self) -> bool:
+        return self.num_scheduler_steps > 1
+
 
 class DeviceConfig:
     device: Optional[torch.device]