Improve tensor parallel performance (#625)

Co-authored-by: Mingyi <wisclmy0611@gmail.com>

README.md

@@ -377,6 +377,14 @@ python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --port
 python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --port 30000 --mem-fraction-static 0.7
 ```
 - See [hyperparameter_tuning.md](docs/hyperparameter_tuning.md) on tuning hyperparameters for better performance.
+- Add `--nnodes 2` to run tensor parallelism on multiple nodes. If you have two nodes with two GPUs on each node and want to run TP=4, let `sgl-dev-1` be the hostname of the first node and `50000` be an available port.
+```
+# Node 0
+python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --tp 4 --nccl-init sgl-dev-1:50000 --nnodes 2 --node-rank 0
+
+# Node 1
+python -m sglang.launch_server --model-path meta-llama/Llama-2-7b-chat-hf --tp 4 --nccl-init sgl-dev-1:50000 --nnodes 2 --node-rank 1
+```
 
 ### Supported Models
 - Llama

benchmark/latency_throughput/bench_one.py

@@ -96,8 +96,11 @@ def run_one_batch_size(bs):
         ret = response.json()
     print(ret)
 
+    input_len = args.input_len if args.input_len else 1
+    output_len = max_new_tokens
+
     output_throughput = bs * max_new_tokens / latency
-    overall_throughput = bs * (args.input_len + max_new_tokens) / latency
+    overall_throughput = bs * (input_len + output_len) / latency
     print(f"latency: {latency:.2f} s")
     print(f"decode throughput: {output_throughput:.2f} token/s")
     print(f"overall throughput: {overall_throughput:.2f} token/s")

benchmark/latency_throughput/bench_serving.py

@@ -312,6 +312,9 @@ def main(args: argparse.Namespace):
         np.sum([output_len for _, output_len, _ in REQUEST_LATENCY]) / benchmark_time
     )
 
+    #latencies = [round(latency, 2) for _, _, latency in REQUEST_LATENCY]
+    #print(latencies)
+
     print(f"Total time: {benchmark_time:.2f} s")
     print(f"Request throughput: {args.num_prompts / benchmark_time:.2f} requests/s")
     print(f"Decoding throughput: {decoding_throughput:.2f} token/s")

python/sglang/README.md

@@ -2,11 +2,10 @@
 
 - `backend`: Various backends for the language interpreter.
 - `lang`: The frontend language.
-- `srt`: The runtime for running local models.
+- `srt`: The serving engine for running local models. (SRT = SGLang Runtime).
 - `test`: Test utilities.
 - `api.py`: Public API.
 - `bench_latency.py`: Benchmark utilities.
 - `global_config.py`: The global configs and constants.
 - `launch_server.py`: The entry point of launching local server.
 - `utils.py`: Common utilities.
-

python/sglang/srt/managers/controller/manager_multi.py

@@ -42,6 +42,8 @@ class LoadBalanceMethod(Enum):
 
 
 class Controller:
+    """A controller that manages multiple data parallel workers."""
+
     def __init__(
         self,
         load_balance_method: str,
@@ -183,9 +185,11 @@ def start_controller_process(
     except Exception:
         pipe_writer.send(get_exception_traceback())
         raise
-
     pipe_writer.send("init ok")
-    loop = asyncio.get_event_loop()
+
+    loop = asyncio.new_event_loop()
+    loop.set_default_executor(ThreadPoolExecutor(max_workers=256))
+
     asyncio.set_event_loop(loop)
     loop.create_task(controller.loop_for_recv_requests())
     loop.run_until_complete(controller.loop_for_forward())

python/sglang/srt/managers/controller/manager_single.py

 """A controller that manages a group of tensor parallel workers."""
 
-import asyncio
+import multiprocessing
 import logging
-from concurrent.futures import ThreadPoolExecutor
+import os
+import pickle
 
-import uvloop
+import torch
+import torch.distributed as dist
 import zmq
 import zmq.asyncio
 
-from sglang.global_config import global_config
-from sglang.srt.managers.controller.tp_worker import ModelTpClient
-from sglang.srt.server_args import PortArgs, ServerArgs
+from sglang.srt.managers.controller.tp_worker import ModelTpServer
+from sglang.srt.server_args import PortArgs, ServerArgs, ModelPortArgs
 from sglang.srt.utils import kill_parent_process
 from sglang.utils import get_exception_traceback
 
-asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
 
 logger = logging.getLogger("srt.controller")
 
 
+def run_tp_server(
+    gpu_id: int,
+    tp_rank: int,
+    server_args: ServerArgs,
+    model_port_args: ModelPortArgs,
+    model_overide_args: dict,
+):
+    """Run a tp server."""
+    try:
+        model_server = ModelTpServer(
+            gpu_id,
+            tp_rank,
+            server_args,
+            model_port_args,
+            model_overide_args,
+        )
+        tp_cpu_group = model_server.model_runner.tp_group.cpu_group
+
+        while True:
+            recv_reqs = broadcast_recv_input(None, tp_rank, tp_cpu_group)
+            model_server.exposed_step(recv_reqs)
+    except Exception:
+        logger.error("Exception in run_tp_server:\n" + get_exception_traceback())
+        raise
+
+
+def launch_tp_servers(gpu_ids, tp_rank_range, server_args,
+                      model_port_args, model_overide_args):
+    """Launch multiple tp servers."""
+    procs = []
+    for i in tp_rank_range:
+        proc = multiprocessing.Process(target=run_tp_server, args=(
+            gpu_ids[i], i, server_args, model_port_args, model_overide_args
+        ))
+        proc.start()
+        procs.append(proc)
+
+    return procs
+
+
+def broadcast_recv_input(data, rank, dist_group):
+    """Broadcast inputs from rank=0 to all other ranks with torch.dist backend."""
+
+    if rank == 0:
+        if len(data) == 0:
+            tensor_size = torch.tensor([0], dtype=torch.long)
+            dist.broadcast(tensor_size, src=0, group=dist_group)
+        else:
+            serialized_data = pickle.dumps(data)
+            size = len(serialized_data)
+            tensor_data = torch.ByteTensor(list(serialized_data))
+            tensor_size = torch.tensor([size], dtype=torch.long)
+
+            dist.broadcast(tensor_size, src=0, group=dist_group)
+            dist.broadcast(tensor_data, src=0, group=dist_group)
+    else:
+        tensor_size = torch.tensor([0], dtype=torch.long)
+        dist.broadcast(tensor_size, src=0, group=dist_group)
+        size = tensor_size.item()
+
+        if size == 0:
+            return []
+
+        tensor_data = torch.empty(size, dtype=torch.uint8)
+        dist.broadcast(tensor_data, src=0, group=dist_group)
+
+        serialized_data = bytes(tensor_data.tolist())
+        data = pickle.loads(serialized_data)
+        return data
+
+
 class ControllerSingle:
-    def __init__(self, model_client: ModelTpClient, port_args: PortArgs):
+    """A controller that manages a group of tensor parallel workers."""
+
+    def __init__(self, server_args: ServerArgs, port_args: PortArgs, model_overide_args: dict):
+        # Parse args
+        self.server_args = server_args
+
         # Init communication
-        context = zmq.asyncio.Context(2)
+        context = zmq.Context(2)
         self.recv_from_tokenizer = context.socket(zmq.PULL)
         self.recv_from_tokenizer.bind(f"tcp://127.0.0.1:{port_args.router_port}")
 
@@ -31,44 +107,52 @@ class ControllerSingle:
             f"tcp://127.0.0.1:{port_args.detokenizer_port}"
         )
 
-        # Init status
-        self.model_client = model_client
-        self.recv_reqs = []
-
-        # Init some configs
-        self.request_dependency_delay = global_config.request_dependency_delay
+        # Init model server
+        tp_size_local = server_args.tp_size // server_args.nnodes
+        gpu_ids = [i for _ in range(server_args.nnodes) for i in range(tp_size_local)]
+
+        # Launch other tp ranks
+        if tp_size_local > 1:
+            tp_rank_range = range(1, tp_size_local)
+            self.tp_procs = launch_tp_servers(
+                gpu_ids, tp_rank_range, server_args,
+                port_args.model_port_args[0], model_overide_args)
+
+        # Launch tp rank 0
+        self.tp_server = ModelTpServer(
+            gpu_ids[0],
+            0,
+            server_args,
+            port_args.model_port_args[0],
+            model_overide_args,
+        )
+        self.tp_cpu_group = self.tp_server.model_runner.tp_group.cpu_group
 
-    async def loop_for_forward(self):
+    def loop_for_forward(self):
         while True:
-            next_step_input = list(self.recv_reqs)
-            self.recv_reqs = []
-            out_pyobjs = await self.model_client.step(next_step_input)
+            recv_reqs = self.recv_requests()
+
+            if self.server_args.tp_size > 1:
+                broadcast_recv_input(recv_reqs, 0, self.tp_cpu_group)
+
+            out_pyobjs = self.tp_server.exposed_step(recv_reqs)
 
             for obj in out_pyobjs:
                 self.send_to_detokenizer.send_pyobj(obj)
 
-            # async sleep for receiving the subsequent request and avoiding cache miss
-            slept = False
-            if len(out_pyobjs) != 0:
-                has_finished = any(
-                    [obj.finished_reason is not None for obj in out_pyobjs]
-                )
-                if has_finished:
-                    if self.request_dependency_delay > 0:
-                        slept = True
-                        await asyncio.sleep(self.request_dependency_delay)
-
-            if not slept:
-                await asyncio.sleep(global_config.wait_for_new_request_delay)
-
-    async def loop_for_recv_requests(self):
+    def recv_requests(self):
+        recv_reqs = []
         while True:
-            recv_req = await self.recv_from_tokenizer.recv_pyobj()
-            self.recv_reqs.append(recv_req)
+            try:
+                recv_req = self.recv_from_tokenizer.recv_pyobj(zmq.NOBLOCK)
+                recv_reqs.append(recv_req)
+            except zmq.ZMQError:
+                break
+        return recv_reqs
 
 
 def start_controller_process(
-    server_args: ServerArgs, port_args: PortArgs, pipe_writer, model_overide_args
+    server_args: ServerArgs, port_args: PortArgs, pipe_writer, model_overide_args: dict
 ):
     logging.basicConfig(
         level=getattr(logging, server_args.log_level.upper()),
@@ -76,27 +160,18 @@ def start_controller_process(
     )
 
     try:
-        tp_size_local = server_args.tp_size // server_args.nnodes
-        model_client = ModelTpClient(
-            [i for _ in range(server_args.nnodes) for i in range(tp_size_local)],
-            server_args,
-            port_args.model_port_args[0],
-            model_overide_args,
-        )
-        controller = ControllerSingle(model_client, port_args)
+        controller = ControllerSingle(server_args, port_args, model_overide_args)
     except Exception:
         pipe_writer.send(get_exception_traceback())
         raise
 
     pipe_writer.send("init ok")
 
-    loop = asyncio.new_event_loop()
-    loop.set_default_executor(ThreadPoolExecutor(max_workers=256))
-    asyncio.set_event_loop(loop)
-    loop.create_task(controller.loop_for_recv_requests())
     try:
-        loop.run_until_complete(controller.loop_for_forward())
+        controller.loop_for_forward()
     except Exception:
         logger.error("Exception in ControllerSingle:\n" + get_exception_traceback())
     finally:
+        for t in controller.tp_procs:
+            os.kill(t.pid, 9)
         kill_parent_process()

python/sglang/srt/managers/controller/model_runner.py

@@ -11,7 +11,7 @@ import torch
 import torch.nn as nn
 from vllm.config import DeviceConfig, LoadConfig
 from vllm.config import ModelConfig as VllmModelConfig
-from vllm.distributed import init_distributed_environment, initialize_model_parallel
+from vllm.distributed import init_distributed_environment, initialize_model_parallel, get_tp_group
 from vllm.model_executor.model_loader import get_model
 from vllm.model_executor.models import ModelRegistry
 
@@ -75,6 +75,7 @@ class ModelRunner:
             distributed_init_method=nccl_init_method,
         )
         initialize_model_parallel(tensor_model_parallel_size=self.tp_size)
+        self.tp_group = get_tp_group()
         total_gpu_memory = get_available_gpu_memory(
             self.gpu_id, distributed=self.tp_size > 1
         )

python/sglang/srt/managers/controller/tp_worker.py

@@ -53,7 +53,7 @@ class ModelTpServer:
         tp_rank: int,
         server_args: ServerArgs,
         model_port_args: ModelPortArgs,
-        model_overide_args,
+        model_overide_args: dict,
     ):
         server_args, model_port_args = obtain(server_args), obtain(model_port_args)
         suppress_other_loggers()
@@ -178,7 +178,7 @@ class ModelTpServer:
         self.new_token_ratio_recovery = global_config.new_token_ratio_recovery
 
     def exposed_step(self, recv_reqs):
-        if self.tp_size * self.dp_size != 1:
+        if not isinstance(recv_reqs, list):
             recv_reqs = obtain(recv_reqs)
 
         try:
@@ -206,11 +206,11 @@ class ModelTpServer:
 
     @torch.inference_mode()
     def forward_step(self):
-        new_batch = self.get_new_fill_batch()
+        new_batch = self.get_new_prefill_batch()
 
         if new_batch is not None:
-            # Run a new fill batch
-            self.forward_fill_batch(new_batch)
+            # Run a new prefill batch
+            self.forward_prefill_batch(new_batch)
             self.cache_filled_batch(new_batch)
 
             if not new_batch.is_empty():
@@ -219,7 +219,7 @@ class ModelTpServer:
                 else:
                     self.running_batch.merge(new_batch)
         else:
-            # Run decode batch
+            # Run a decode batch
             if self.running_batch is not None:
                 # Run a few decode batches continuously for reducing overhead
                 for _ in range(global_config.num_continue_decode_steps):
@@ -312,7 +312,7 @@ class ModelTpServer:
         )
         self.forward_queue.append(req)
 
-    def get_new_fill_batch(self) -> Optional[Batch]:
+    def get_new_prefill_batch(self) -> Optional[Batch]:
         running_bs = (
             len(self.running_batch.reqs) if self.running_batch is not None else 0
         )
@@ -436,7 +436,7 @@ class ModelTpServer:
         self.forward_queue = [x for x in self.forward_queue if x not in can_run_list]
         return new_batch
 
-    def forward_fill_batch(self, batch: Batch):
+    def forward_prefill_batch(self, batch: Batch):
         # Build batch tensors
         batch.prepare_for_extend(
             self.model_config.vocab_size, self.int_token_logit_bias
@@ -746,8 +746,8 @@ class ModelTpClient:
             # Init model
             assert len(gpu_ids) == 1
             self.model_server = ModelTpService().exposed_ModelTpServer(
-                0,
                 gpu_ids[0],
+                0,
                 server_args,
                 model_port_args,
                 model_overide_args,

python/sglang/srt/server.py

@@ -33,9 +33,9 @@ from sglang.srt.managers.controller.manager_multi import (
     start_controller_process as start_controller_process_multi,
 )
 from sglang.srt.managers.controller.manager_single import (
+    launch_tp_servers,
     start_controller_process as start_controller_process_single,
 )
-from sglang.srt.managers.controller.tp_worker import ModelTpService
 from sglang.srt.managers.detokenizer_manager import start_detokenizer_process
 from sglang.srt.managers.io_struct import GenerateReqInput
 from sglang.srt.managers.tokenizer_manager import TokenizerManager
@@ -53,7 +53,6 @@ from sglang.srt.utils import (
     enable_show_time_cost,
     receive_addrs,
     send_addrs_to_rank_0,
-    start_rpyc_service_process,
 )
 from sglang.utils import get_exception_traceback
 
@@ -192,21 +191,17 @@ def launch_server(server_args: ServerArgs, pipe_finish_writer, model_overide_arg
         model_port_args=model_port_args,
     )
 
-    # TODO multi-node dp is not supported
-    assert not (server_args.dp_size > 1 and server_args.node_rank is not None)
+    # Handle multi-node tp
     if server_args.nnodes > 1:
+        assert server_args.dp_size == 1, "Multi-node dp is not supported."
+
         if server_args.node_rank != 0:
-            send_addrs_to_rank_0(model_port_args[0], server_args)
-        else:
-            receive_addrs(model_port_args[0], server_args)
-        for i in range(tp_size_local):
-            start_rpyc_service_process(
-                ModelTpService, model_port_args[0].model_tp_ports[i]
-            )
-        if server_args.node_rank != 0:
-            logger.info(
-                f"[node_rank={server_args.node_rank}]: Listen for connections..."
-            )
+            tp_size_local = server_args.tp_size // server_args.nnodes
+            gpu_ids = [i for _ in range(server_args.nnodes) for i in range(tp_size_local)]
+            tp_rank_range = list(range(server_args.node_rank * tp_size_local,
+                                  (server_args.node_rank + 1) * tp_size_local))
+            procs = launch_tp_servers(gpu_ids, tp_rank_range, server_args,
+                                      port_args.model_port_args[0], model_overide_args)
             while True:
                 pass
 

python/sglang/srt/server_args.py

@@ -67,10 +67,12 @@ class ServerArgs:
         if self.tokenizer_path is None:
             self.tokenizer_path = self.model_path
         if self.mem_fraction_static is None:
-            if self.tp_size >= 8:
+            if self.tp_size >= 16:
+                self.mem_fraction_static = 0.74
+            elif self.tp_size >= 8:
                 self.mem_fraction_static = 0.78
             elif self.tp_size >= 4:
-                self.mem_fraction_static = 0.80
+                self.mem_fraction_static = 0.82
             elif self.tp_size >= 2:
                 self.mem_fraction_static = 0.85
             else: