[Feature] Pluggable platform-specific scheduler (#13161)

Signed-off-by: Yannick Schnider <yannick.schnider1@ibm.com>
Signed-off-by: Yannick Schnider <Yannick.Schnider1@ibm.com>

vllm/engine/llm_engine.py

@@ -19,8 +19,7 @@ import vllm.envs as envs
 from vllm.config import (DecodingConfig, LoRAConfig, ModelConfig,
                          ObservabilityConfig, ParallelConfig, SchedulerConfig,
                          VllmConfig)
-from vllm.core.scheduler import (ScheduledSequenceGroup, Scheduler,
-                                 SchedulerOutputs)
+from vllm.core.scheduler import ScheduledSequenceGroup, SchedulerOutputs
 from vllm.engine.arg_utils import EngineArgs
 from vllm.engine.metrics_types import StatLoggerBase, Stats
 from vllm.engine.output_processor.interfaces import (
@@ -58,7 +57,8 @@ from vllm.transformers_utils.tokenizer_group import (
     BaseTokenizerGroup, init_tokenizer_from_configs)
 from vllm.usage.usage_lib import (UsageContext, is_usage_stats_enabled,
                                   usage_message)
-from vllm.utils import Counter, Device, deprecate_kwargs, weak_bind
+from vllm.utils import (Counter, Device, deprecate_kwargs,
+                        resolve_obj_by_qualname, weak_bind)
 from vllm.version import __version__ as VLLM_VERSION
 
 logger = init_logger(__name__)
@@ -346,6 +346,11 @@ class LLMEngine:
         # Create the scheduler.
         # NOTE: the cache_config here have been updated with the numbers of
         # GPU and CPU blocks, which are profiled in the distributed executor.
+        if isinstance(self.vllm_config.scheduler_config.scheduler_cls, str):
+            Scheduler = resolve_obj_by_qualname(
+                self.vllm_config.scheduler_config.scheduler_cls)
+        else:
+            Scheduler = self.vllm_config.scheduler_config.scheduler_cls
         self.scheduler = [
             Scheduler(
                 self.scheduler_config, self.cache_config, self.lora_config,