[core][distributed] exact ray placement control (#12732)

Signed-off-by: youkaichao <youkaichao@gmail.com>

vllm/envs.py

@@ -85,6 +85,8 @@ if TYPE_CHECKING:
     VLLM_MLA_DISABLE_REQUANTIZATION: bool = False
     VLLM_MLA_CUDA_MEM_ALIGN_KV_CACHE: bool = True
     VLLM_ENABLE_MOE_ALIGN_BLOCK_SIZE_TRITON: bool = False
+    VLLM_RAY_PER_WORKER_GPUS: float = 1.0
+    VLLM_RAY_BUNDLE_INDICES: str = ""
 
 
 def get_default_cache_root():
@@ -550,6 +552,18 @@ environment_variables: Dict[str, Callable[[], Any]] = {
     lambda: bool(int(os.getenv("VLLM_ENABLE_MOE_ALIGN_BLOCK_SIZE_TRITON", "0"))
                  ),
 
+    # Number of GPUs per worker in Ray, if it is set to be a fraction,
+    # it allows ray to schedule multiple actors on a single GPU,
+    # so that users can colocate other actors on the same GPUs as vLLM.
+    "VLLM_RAY_PER_WORKER_GPUS":
+    lambda: float(os.getenv("VLLM_RAY_PER_WORKER_GPUS", "1.0")),
+
+    # Bundle indices for Ray, if it is set, it can control precisely
+    # which indices are used for the Ray bundle, for every worker.
+    # Format: comma-separated list of integers, e.g. "0,1,2,3"
+    "VLLM_RAY_BUNDLE_INDICES":
+    lambda: os.getenv("VLLM_RAY_BUNDLE_INDICES", ""),
+
     # When on a Nvidia GPU aligns single entries (within a page) so they are 256
     # byte aligned for better performance, this increases the memory usage of
     # the cache. Currently this only affects MLA that results in non-256