add env

vllm/attention/layer.py

@@ -380,9 +380,9 @@ def wait_for_kv_layer_from_connector(layer_name: str):
     assert isinstance(attn_metadata, dict)
     connector.wait_for_layer_load(layer_name)
 
-    get_lmcache_connector().wait_for_layer_load(layer_name)
-
-
+    lmcache_connector = get_lmcache_connector()
+    if lmcache_connector is not None:
+        lmcache_connector.wait_for_layer_load(layer_name)
 
 def maybe_save_kv_layer_to_connector(
     layer_name: str,
@@ -400,9 +400,11 @@ def maybe_save_kv_layer_to_connector(
     assert isinstance(attn_metadata, dict)
     connector.save_kv_layer(layer_name, kv_cache_layer,
                             attn_metadata[layer_name])
-    get_lmcache_connector().save_kv_layer(layer_name, kv_cache_layer,
-                            attn_metadata[layer_name])
     
+    lmcache_connector = get_lmcache_connector()
+    if lmcache_connector is not None:
+        lmcache_connector.save_kv_layer(layer_name, kv_cache_layer,
+                            attn_metadata[layer_name])
 
 def unified_attention(
     query: torch.Tensor,

vllm/distributed/kv_transfer/kv_transfer_state.py

@@ -25,8 +25,6 @@ def get_kv_transfer_group() -> KVConnectorBaseType:
     return _KV_CONNECTOR_AGENT
 
 def get_lmcache_connector() -> KVConnectorBaseType:
-    assert _KV_LMCACHE_CONNECTOR_AGENT is not None, (
-        "LM cache transfer parallel group is not initialized")
     return _KV_LMCACHE_CONNECTOR_AGENT
 
 
@@ -64,7 +62,7 @@ def ensure_kv_transfer_initialized(vllm_config: "VllmConfig") -> None:
     global _KV_CONNECTOR_AGENT
     global _KV_LMCACHE_CONNECTOR_AGENT
 
-    if _KV_LMCACHE_CONNECTOR_AGENT is None:
+    if envs.VLLM_LMCACHE_ENABLE and _KV_LMCACHE_CONNECTOR_AGENT is None:
         lmcache_config = copy.deepcopy(vllm_config)
         from vllm.config import KVTransferConfig
         lmcache_config.kv_transfer_config = KVTransferConfig(kv_connector="LMCacheConnectorV1", kv_role="kv_both")

vllm/envs.py

@@ -169,6 +169,7 @@ if TYPE_CHECKING:
     USE_FUSED_RMS_QUANT: bool = False
     VLLM_USE_MERGE_ATTN_STATES_OPT: bool = False
     USE_FUSED_SILU_MUL_QUANT: bool = False
+    VLLM_LMCACHE_ENABLE: bool = False
 
 def get_default_cache_root():
     return os.getenv(
@@ -1114,6 +1115,10 @@ environment_variables: dict[str, Callable[[], Any]] = {
     "USE_FUSED_SILU_MUL_QUANT": 
     lambda: (os.getenv('USE_FUSED_SILU_MUL_QUANT', '0').lower() in
              ("true", "1")),
+    "VLLM_LMCACHE_ENABLE":
+        lambda: (os.environ.get("VLLM_LMCACHE_ENABLE", "False").lower() in
+                 ("true", "1")),
+
 }
 
 # --8<-- [end:env-vars-definition]

vllm/v1/core/sched/scheduler.py

@@ -10,6 +10,7 @@ from collections import defaultdict
 from collections.abc import Iterable
 from typing import Any, Optional, Union
 
+import vllm.envs as envs
 from vllm.config import KVTransferConfig,VllmConfig
 from vllm.distributed.kv_events import EventPublisherFactory, KVEventBatch
 from vllm.distributed.kv_transfer.kv_connector.factory import (
@@ -88,6 +89,7 @@ class Scheduler(SchedulerInterface):
             self.connector = KVConnectorFactory.create_connector_v1(
                 config=self.vllm_config, role=KVConnectorRole.SCHEDULER)
 
+        if envs.VLLM_LMCACHE_ENABLE:
             lmcache_config = copy.deepcopy(self.vllm_config)
             lmcache_config.kv_transfer_config = KVTransferConfig(kv_connector="LMCacheConnectorV1", kv_role="kv_both")
             lmcache_config.kv_transfer_config.engine_id = "ed9e943a-e455-4ed6-b88c-09ae6263f0c9"

vllm/v1/worker/gpu_model_runner.py

@@ -1577,7 +1577,9 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         if has_kv_transfer_group():
             get_kv_transfer_group().clear_connector_metadata()
 
-        get_lmcache_connector().clear_connector_metadata()
+        lmcache_connector = get_lmcache_connector()
+        if lmcache_connector is not None:
+            lmcache_connector.clear_connector_metadata()
 
         self.eplb_step()
 
@@ -1743,6 +1745,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             kv_connector.start_load_kv(get_forward_context())
 
         lmcache_connector = get_lmcache_connector()
+        if lmcache_connector is not None:
             lmcache_connector.bind_connector_metadata(
                 scheduler_output.kv_connector_metadata)
             lmcache_connector.start_load_kv(get_forward_context())
@@ -1753,6 +1756,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             get_kv_transfer_group().wait_for_save()
 
         lmcache_connector = get_lmcache_connector()
+        if lmcache_connector is not None:
             lmcache_connector.wait_for_save()
 
     @staticmethod
@@ -2704,7 +2708,9 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         if has_kv_transfer_group():
             get_kv_transfer_group().register_kv_caches(kv_caches)
 
-        get_lmcache_connector().register_kv_caches(kv_caches)
+        lmcache_connector = get_lmcache_connector()
+        if lmcache_connector is not None:
+            lmcache_connector.register_kv_caches(kv_caches)
 
     def get_kv_cache_spec(self) -> dict[str, KVCacheSpec]:
         """

vllm/zero_overhead/v1/gpu_model_runner.py

@@ -727,7 +727,9 @@ class V1ZeroModelRunner(GPUModelRunner):
         if has_kv_transfer_group():
             get_kv_transfer_group().clear_connector_metadata()
 
-        get_lmcache_connector().clear_connector_metadata()
+        lmcache_connector = get_lmcache_connector()
+        if lmcache_connector is not None:
+            lmcache_connector.clear_connector_metadata()
 
         self.eplb_step()