327 lines
13 KiB
Python
327 lines
13 KiB
Python
#!/usr/bin/env python3
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"""Profile the vLLM 0.20 TP all-reduce path under a frozen runtime contract."""
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from __future__ import annotations
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import argparse
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import json
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import os
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import statistics
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import subprocess
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from pathlib import Path
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from typing import Any
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import torch
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import torch.distributed as dist
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import vllm
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VLLM_VERSION = "0.20.0"
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VLLM_COMMIT = "88d34c6409e9fb3c7b8ca0c04756f061d2099eb1"
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def parse_args() -> argparse.Namespace:
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parser = argparse.ArgumentParser()
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parser.add_argument("--vllm-source", type=Path, required=True)
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parser.add_argument("--model", type=Path, required=True)
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parser.add_argument("--output", type=Path, required=True)
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parser.add_argument("--num-tokens", type=int, nargs="+", default=[8])
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parser.add_argument("--hidden-dim", type=int, default=2048)
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parser.add_argument(
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"--collective-contract",
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choices=("flashinfer-trtllm", "qwen235-serving-projected"),
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default="flashinfer-trtllm",
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)
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parser.add_argument("--warmup-iters", type=int, default=3)
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parser.add_argument("--repeats", type=int, default=10)
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parser.add_argument("--trials", type=int, default=1)
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return parser.parse_args()
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def git_head(repo: Path) -> str:
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return subprocess.check_output(
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["git", "-C", str(repo), "rev-parse", "HEAD"], text=True
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).strip()
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def stats_ms(samples: list[float]) -> dict[str, float]:
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return {
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"min": min(samples),
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"max": max(samples),
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"mean": statistics.fmean(samples),
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"median": statistics.median(samples),
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"std": statistics.pstdev(samples),
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}
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def main() -> None:
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args = parse_args()
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if vllm.__version__ != VLLM_VERSION:
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raise SystemExit(f"expected vLLM {VLLM_VERSION}, got {vllm.__version__}")
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source_head = git_head(args.vllm_source)
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if source_head != VLLM_COMMIT:
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raise SystemExit(f"expected vLLM source {VLLM_COMMIT}, got {source_head}")
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if args.repeats <= 0 or args.trials <= 0 or args.warmup_iters < 0:
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raise SystemExit("warmup/repeats/trials must be non-negative/positive")
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if os.getenv("VLLM_ALLREDUCE_USE_FLASHINFER") != "1":
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raise SystemExit("VLLM_ALLREDUCE_USE_FLASHINFER must equal 1")
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if os.getenv("VLLM_FLASHINFER_ALLREDUCE_BACKEND") != "trtllm":
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raise SystemExit("VLLM_FLASHINFER_ALLREDUCE_BACKEND must equal trtllm")
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expected_symm_mem = (
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"1" if args.collective_contract == "qwen235-serving-projected" else "0"
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)
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if os.getenv("VLLM_ALLREDUCE_USE_SYMM_MEM") != expected_symm_mem:
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raise SystemExit(
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f"VLLM_ALLREDUCE_USE_SYMM_MEM must equal {expected_symm_mem}"
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)
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if "RANK" not in os.environ or "WORLD_SIZE" not in os.environ:
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raise SystemExit("launch with torchrun")
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from vllm.distributed import (
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destroy_distributed_environment,
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destroy_model_parallel,
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init_distributed_environment,
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initialize_model_parallel,
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set_custom_all_reduce,
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tensor_model_parallel_all_reduce,
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)
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from vllm.distributed.parallel_state import get_tp_group
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from vllm.config import (
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ModelConfig,
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ParallelConfig,
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VllmConfig,
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set_current_vllm_config,
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)
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rank = int(os.environ["RANK"])
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local_rank = int(os.environ["LOCAL_RANK"])
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world_size = int(os.environ["WORLD_SIZE"])
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if world_size not in (2, 4, 8):
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raise SystemExit(f"expected TP world size 2, 4, or 8, got {world_size}")
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device = torch.device(f"cuda:{local_rank}")
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torch.accelerator.set_device_index(device)
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torch.set_default_device(device)
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disable_custom_all_reduce = (
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args.collective_contract == "qwen235-serving-projected"
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)
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set_custom_all_reduce(not disable_custom_all_reduce)
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init_distributed_environment()
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model_config = ModelConfig(
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model=str(args.model),
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dtype="bfloat16",
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max_model_len=8192,
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skip_tokenizer_init=True,
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generation_config="vllm",
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)
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vllm_config = VllmConfig(
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model_config=model_config,
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parallel_config=ParallelConfig(
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tensor_parallel_size=world_size,
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disable_custom_all_reduce=disable_custom_all_reduce,
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)
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)
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with set_current_vllm_config(vllm_config):
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initialize_model_parallel(tensor_model_parallel_size=world_size)
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from vllm.distributed.device_communicators.all_reduce_utils import (
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should_nccl_symm_mem_allreduce,
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)
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def resolve_profile_operation(input_tensor: torch.Tensor):
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communicator = get_tp_group().device_communicator
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if args.collective_contract == "qwen235-serving-projected":
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from vllm.compilation.passes.fusion.allreduce_rms_fusion import (
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FI_ALLREDUCE_FUSION_MAX_SIZE_MB,
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)
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major, minor = torch.cuda.get_device_capability(device)
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capability = major * 10 + minor
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try:
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fusion_limit_bytes = int(
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FI_ALLREDUCE_FUSION_MAX_SIZE_MB[capability][world_size]
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* 1024
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* 1024
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)
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except KeyError as error:
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raise SystemExit(
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f"no FlashInfer fusion limit for SM{capability}, TP{world_size}"
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) from error
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if input_tensor.nbytes <= fusion_limit_bytes:
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fi_comm = communicator.fi_ar_comm
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if fi_comm is None or fi_comm.disabled:
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raise SystemExit("FlashInfer all-reduce communicator is unavailable")
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if not fi_comm.should_use_fi_ar(input_tensor):
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raise SystemExit("FlashInfer rejected a fusion-eligible payload")
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return (
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"flashinfer_trtllm_fused_projection",
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fi_comm.all_reduce,
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fusion_limit_bytes,
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)
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if (
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communicator.pynccl_comm is not None
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and should_nccl_symm_mem_allreduce(world_size, input_tensor)
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):
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return (
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"pynccl_symmetric_with_copy",
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torch.ops.vllm.all_reduce_symmetric_with_copy,
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fusion_limit_bytes,
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)
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if (
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communicator.symm_mem_comm is not None
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and communicator.symm_mem_comm.should_use_symm_mem(input_tensor)
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):
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return (
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"torch_symmetric_memory",
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communicator.symm_mem_comm.all_reduce,
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fusion_limit_bytes,
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)
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if communicator.pynccl_comm is not None:
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return "pynccl", communicator.pynccl_comm.all_reduce, fusion_limit_bytes
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return "torch_distributed", tensor_model_parallel_all_reduce, fusion_limit_bytes
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fi_comm = communicator.fi_ar_comm
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selected_backend = (
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"flashinfer_trtllm"
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if fi_comm is not None
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and not fi_comm.disabled
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and fi_comm.should_use_fi_ar(input_tensor)
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else "non_flashinfer_fallback"
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)
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return selected_backend, tensor_model_parallel_all_reduce, None
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rows: list[dict[str, Any]] = []
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expected_sum = world_size * (world_size + 1) / 2
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try:
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for num_tokens in args.num_tokens:
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input_tensor = torch.full(
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(num_tokens, args.hidden_dim),
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float(rank + 1),
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dtype=torch.bfloat16,
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device=device,
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)
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selected_backend, profile_operation, fusion_limit_bytes = (
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resolve_profile_operation(input_tensor)
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)
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for _ in range(args.warmup_iters):
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output = profile_operation(input_tensor)
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torch.accelerator.synchronize()
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torch.testing.assert_close(
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output,
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torch.full_like(output, expected_sum),
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atol=0.0,
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rtol=0.0,
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)
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if args.collective_contract == "flashinfer-trtllm":
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if selected_backend != "flashinfer_trtllm":
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raise SystemExit(
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f"expected FlashInfer TRTLLM, got {selected_backend} at "
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f"TP={world_size}, tokens={num_tokens}"
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)
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elif selected_backend not in {
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"flashinfer_trtllm_fused_projection",
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"pynccl_symmetric_with_copy",
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"torch_symmetric_memory",
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"pynccl",
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}:
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raise SystemExit(
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f"unexpected Qwen235 serving backend: {selected_backend}"
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)
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all_trial_rank_samples: list[list[list[float]]] = []
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critical_path_samples: list[float] = []
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for _ in range(args.trials):
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samples: list[float] = []
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for _ in range(args.repeats):
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dist.barrier()
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start = torch.cuda.Event(enable_timing=True)
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end = torch.cuda.Event(enable_timing=True)
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start.record()
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output = profile_operation(input_tensor)
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end.record()
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torch.accelerator.synchronize()
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samples.append(float(start.elapsed_time(end)))
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gathered: list[list[float] | None] = [None] * world_size
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dist.all_gather_object(gathered, samples)
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if rank == 0:
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rank_samples = [item for item in gathered if item is not None]
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all_trial_rank_samples.append(rank_samples)
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critical_path_samples.extend(
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max(per_rank[index] for per_rank in rank_samples)
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for index in range(args.repeats)
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)
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if rank == 0:
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flattened_by_rank = [
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[
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sample
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for trial in all_trial_rank_samples
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for sample in trial[rank_index]
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]
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for rank_index in range(world_size)
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]
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per_rank = [stats_ms(samples) for samples in flattened_by_rank]
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row = {
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"tensor_parallel_size": world_size,
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"num_tokens": num_tokens,
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"hidden_dim": args.hidden_dim,
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"payload_bytes": num_tokens
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* args.hidden_dim
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* torch.tensor([], dtype=torch.bfloat16).element_size(),
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"dtype": "bfloat16",
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"communicator": "vllm.tensor_model_parallel_all_reduce",
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"collective_contract": args.collective_contract,
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"selected_backend": selected_backend,
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"real_fusion_limit_bytes": fusion_limit_bytes,
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"trials": args.trials,
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"repeats_per_trial": args.repeats,
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"per_trial_rank_samples_ms": all_trial_rank_samples,
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"per_rank_time_ms": per_rank,
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"critical_path_time_ms": stats_ms(critical_path_samples),
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"critical_path_median_ms": statistics.median(
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critical_path_samples
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),
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}
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rows.append(row)
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print(json.dumps(row, sort_keys=True), flush=True)
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finally:
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destroy_model_parallel()
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destroy_distributed_environment()
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if rank == 0:
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payload = {
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"schema_version": (
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"qwen30_vllm020_allreduce_raw.v1"
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if args.collective_contract == "flashinfer-trtllm"
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else "vllm020_allreduce_raw.v2"
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),
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"environment": {
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"vllm_version": vllm.__version__,
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"vllm_source_commit": source_head,
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"torch_version": torch.__version__,
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"torch_cuda": torch.version.cuda,
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"gpu": torch.cuda.get_device_name(device),
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"model": str(args.model),
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"backend_env": {
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"VLLM_ALLREDUCE_USE_FLASHINFER": os.getenv(
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"VLLM_ALLREDUCE_USE_FLASHINFER", "0"
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),
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"VLLM_FLASHINFER_ALLREDUCE_BACKEND": os.getenv(
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"VLLM_FLASHINFER_ALLREDUCE_BACKEND"
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),
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"VLLM_ALLREDUCE_USE_SYMM_MEM": os.getenv(
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"VLLM_ALLREDUCE_USE_SYMM_MEM", "1"
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),
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},
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"collective_contract": args.collective_contract,
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"disable_custom_all_reduce": disable_custom_all_reduce,
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},
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"rows": rows,
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}
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args.output.parent.mkdir(parents=True, exist_ok=True)
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args.output.write_text(json.dumps(payload, indent=2, sort_keys=True) + "\n")
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if __name__ == "__main__":
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main()
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