[Kernel] Refactor FlashInfer allreduce for mnnvl backend (vllm-project#34109)

Signed-off-by: hjjq <50634613+hjjq@users.noreply.github.com>
Signed-off-by: wzhao18 <wzhao18.sz@gmail.com>
Co-authored-by: wzhao18 <wzhao18.sz@gmail.com>
Co-authored-by: Wei Zhao <51183510+wzhao18@users.noreply.github.com>

Author: hjjq

benchmarks/kernels/benchmark_device_communicators.py

@@ -30,6 +30,9 @@
 from torch.distributed import ProcessGroup
 
 from vllm.distributed.device_communicators.custom_all_reduce import CustomAllreduce
+from vllm.distributed.device_communicators.flashinfer_all_reduce import (
+    FlashInferAllReduce,
+)
 from vllm.distributed.device_communicators.pynccl import (
     PyNcclCommunicator,
     register_nccl_symmetric_ops,
@@ -44,7 +47,7 @@
 logger = init_logger(__name__)
 
 # Default sequence lengths to benchmark
-DEFAULT_SEQUENCE_LENGTHS = [128, 512, 1024, 2048, 4096, 8192]
+DEFAULT_SEQUENCE_LENGTHS = [16, 64, 128, 512, 1024, 2048, 4096, 8192]
 
 # Fixed hidden size and dtype for all benchmarks
 HIDDEN_SIZE = 8192
@@ -81,6 +84,7 @@ def __init__(
         self.symm_mem_comm = None
         self.symm_mem_comm_multimem = None
         self.symm_mem_comm_two_shot = None
+        self.fi_ar_comm = None
 
         self._init_communicators()
 
@@ -161,6 +165,22 @@ def _init_communicators(self):
             )
             self.symm_mem_comm_two_shot = None
 
+        try:
+            self.fi_ar_comm = FlashInferAllReduce(
+                group=self.cpu_group,
+                device=self.device,
+            )
+            if not self.fi_ar_comm.disabled:
+                logger.info("Rank %s: FlashInferAllReduce initialized", self.rank)
+            else:
+                logger.info("Rank %s: FlashInferAllReduce disabled", self.rank)
+                self.fi_ar_comm = None
+        except Exception as e:
+            logger.warning(
+                "Rank %s: Failed to initialize FlashInferAllReduce: %s", self.rank, e
+            )
+            self.fi_ar_comm = None
+
     def benchmark_allreduce(
         self, sequence_length: int, num_warmup: int, num_trials: int
     ) -> dict[str, float]:
@@ -180,7 +200,8 @@ def benchmark_allreduce(
                     lambda t, c=comm: c.custom_all_reduce(t),
                     lambda t, c=comm: c.should_custom_ar(t),
                     comm.capture(),
-                    "1stage",  # env variable value
+                    {"VLLM_CUSTOM_ALLREDUCE_ALGO": "1stage"},
+                    None,  # no destroy function
                 )
             )
             # CustomAllreduce two-shot
@@ -190,7 +211,8 @@ def benchmark_allreduce(
                     lambda t, c=comm: c.custom_all_reduce(t),
                     lambda t, c=comm: c.should_custom_ar(t),
                     comm.capture(),
-                    "2stage",  # env variable value
+                    {"VLLM_CUSTOM_ALLREDUCE_ALGO": "2stage"},
+                    None,  # no destroy function
                 )
             )
 
@@ -202,7 +224,8 @@ def benchmark_allreduce(
                     lambda t, c=comm: c.all_reduce(t),
                     lambda t: True,  # Always available if initialized
                     nullcontext(),
-                    None,  # no env variable needed
+                    {},  # no env variable needed
+                    None,  # no destroy function
                 )
             )
             communicators.append(
@@ -211,7 +234,8 @@ def benchmark_allreduce(
                     lambda t: torch.ops.vllm.all_reduce_symmetric_with_copy(t),
                     lambda t: True,  # Always available if initialized
                     nullcontext(),
-                    None,  # no env variable needed
+                    {},  # no env variable needed
+                    None,  # no destroy function
                 )
             )
 
@@ -223,7 +247,8 @@ def benchmark_allreduce(
                     lambda t, c=comm: c.all_reduce(t),
                     lambda t, c=comm: c.should_use_symm_mem(t),
                     nullcontext(),
-                    None,  # no env variable needed
+                    {},  # no env variable needed
+                    None,  # no destroy function
                 )
             )
 
@@ -235,29 +260,67 @@ def benchmark_allreduce(
                     lambda t, c=comm: c.all_reduce(t),
                     lambda t, c=comm: c.should_use_symm_mem(t),
                     nullcontext(),
-                    None,  # no env variable needed
+                    {},  # no env variable needed
+                    None,  # no destroy function needed
                 )
             )
 
-        # Benchmark each communicator
-        for name, allreduce_fn, should_use_fn, context, env_var in communicators:
-            # Set environment variable if needed
-            if env_var is not None:
-                os.environ["VLLM_CUSTOM_ALLREDUCE_ALGO"] = env_var
-            else:
-                # Clear the environment variable to avoid interference
-                os.environ.pop("VLLM_CUSTOM_ALLREDUCE_ALGO", None)
-
-            latency = self.benchmark_allreduce_single(
-                sequence_length,
-                allreduce_fn,
-                should_use_fn,
-                context,
-                num_warmup,
-                num_trials,
+        if self.fi_ar_comm is not None:
+            comm = self.fi_ar_comm
+            communicators.append(
+                (
+                    "flashinfer_trtllm",
+                    lambda t, c=comm: c.all_reduce(t),
+                    lambda t, c=comm: c.should_use_fi_ar(t),
+                    nullcontext(),
+                    {"VLLM_FLASHINFER_ALLREDUCE_BACKEND": "trtllm"},
+                    lambda c=comm: c.destroy(),
+                )
             )
-            if latency is not None:
-                results[name] = latency
+            communicators.append(
+                (
+                    "flashinfer_mnnvl",
+                    lambda t, c=comm: c.all_reduce(t),
+                    lambda t, c=comm: c.should_use_fi_ar(t),
+                    nullcontext(),
+                    {"VLLM_FLASHINFER_ALLREDUCE_BACKEND": "mnnvl"},
+                    lambda c=comm: c.destroy(),
+                )
+            )
+
+        # Benchmark each communicator
+        for (
+            name,
+            allreduce_fn,
+            should_use_fn,
+            context,
+            env_dict,
+            destroy_fn,
+        ) in communicators:
+            # Save original values and apply new environment variables
+            saved_env = {key: os.environ.get(key) for key in env_dict}
+            for key, value in env_dict.items():
+                os.environ[key] = value
+            try:
+                latency = self.benchmark_allreduce_single(
+                    sequence_length,
+                    allreduce_fn,
+                    should_use_fn,
+                    context,
+                    num_warmup,
+                    num_trials,
+                )
+                if latency is not None:
+                    results[name] = latency
+            finally:
+                if destroy_fn is not None:
+                    destroy_fn()
+                # Restore environment variables to their original state
+                for key, original_value in saved_env.items():
+                    if original_value is None:
+                        os.environ.pop(key, None)
+                    else:
+                        os.environ[key] = original_value
 
         return results