[Doc] cleanup TPU documentation and remove outdated examples (#29048)

Signed-off-by: Rob Mulla <rob.mulla@gmail.com>
Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>
Co-authored-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>
This commit is contained in:
Rob Mulla
2025-11-20 19:05:59 -05:00
committed by GitHub
parent c7a29d2c8d
commit dd39f91edb
8 changed files with 40 additions and 415 deletions

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# vLLM TPU Profiling
This script is used to profile the TPU performance of vLLM for specific prefill or decode token shapes.
Note: an actual running server is a mix of both prefill of many shapes and decode of many shapes.
We assume you are on a TPU already (this was tested on TPU v6e) and have installed vLLM according to the [Google TPU installation guide](https://docs.vllm.ai/en/latest/getting_started/installation/google_tpu.html).
> In all examples below, we run several warmups before (so `--enforce-eager` is okay)
## Profile Examples
### Generate Prefill Trace
This example runs Qwen/Qwen2.5-7B-Instruct with a single request of 1024 input tokens. This is set up in attempt to profile just the prefill time and operations.
```bash
export XLA_HLO_DEBUG=1
export MODEL=Qwen/Qwen2.5-7B-Instruct
export VLLM_TPU_PROFILE_DURATION_MS=3000
export VLLM_TPU_PROFILE_DELAY_MS=0
python3 profiling.py \
--model $MODEL \
--input-len 1024 --output-len 1 \
--batch-size 1 --enforce-eager \
--max-model-len 2048 \
--tensor-parallel-size 1 \
--profile-result-dir profiles
```
### Generate Decode Trace
This example runs Llama 3.1 70B with a batch of 32 requests where each has 1 input token and 128 output tokens. This is set up in attempt to profile just the 32 decodes running in parallel by having an extremely small prefill of 1 token and setting `VLLM_TPU_PROFILE_DELAY_MS=1000` to skip the first second of inference (hopefully prefill).
```bash
export XLA_HLO_DEBUG=1
export MODEL=meta-llama/Llama-3.1-70B-Instruct
export VLLM_TPU_PROFILE_DURATION_MS=2000
export VLLM_TPU_PROFILE_DELAY_MS=1000
rm -rf ~/.cache/vllm/xla_cache
python3 profiling.py \
--model $MODEL \
--input-len 1 \
--output-len 128 \
--batch-size 32 \
--enforce-eager \
--profile-result-dir profiles \
--max-model-len 2048 --tensor-parallel-size 8
```
## Visualizing the profiles
Once you have collected your profiles with this script, you can visualize them using [TensorBoard](https://cloud.google.com/tpu/docs/pytorch-xla-performance-profiling-tpu-vm).
Here are most likely the dependencies you need to install:
```bash
pip install tensorflow-cpu \
tensorboard-plugin-profile \
etils \
importlib_resources
```
Then you just need to point TensorBoard to the directory where you saved the profiles and visit `http://localhost:6006/` in your browser:
```bash
tensorboard --logdir profiles/ --port 6006
```

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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import argparse
import dataclasses
import os
import time
import numpy as np
import torch_xla.debug.profiler as xp
from tqdm import tqdm
from vllm import LLM, SamplingParams
from vllm.engine.arg_utils import EngineArgs
from vllm.inputs import PromptType
from vllm.utils.argparse_utils import FlexibleArgumentParser
DURATION_MS = int(os.getenv("VLLM_TPU_PROFILE_DURATION_MS", 3000))
DELAY_MS = int(os.getenv("VLLM_TPU_PROFILE_DELAY_MS", 0))
def main(args: argparse.Namespace):
print(args)
engine_args = EngineArgs.from_cli_args(args)
llm = LLM(**dataclasses.asdict(engine_args))
server = xp.start_server(9012) # noqa: F841
sampling_params = SamplingParams(
temperature=0.0,
ignore_eos=True,
max_tokens=args.output_len,
)
print(sampling_params)
dummy_prompt_token_ids = np.random.randint(
10000, size=(args.batch_size, args.input_len)
)
dummy_prompts: list[PromptType] = [
{"prompt_token_ids": batch} for batch in dummy_prompt_token_ids.tolist()
]
def run_to_completion():
start_time = time.perf_counter()
llm.generate(dummy_prompts, sampling_params=sampling_params, use_tqdm=False)
end_time = time.perf_counter()
latency = end_time - start_time
return latency
# Warmup
print("Warming up...")
warmup_latencies = []
for _ in tqdm(range(args.num_iters_warmup), desc="Warmup iterations"):
warmup_latencies.append(run_to_completion())
print(f"Average warmup latency: {np.mean(warmup_latencies):.4f}s")
# Profile
profile_dir = args.profile_result_dir
print(f"Profiling (results will be saved to '{profile_dir}')...")
# Enable tracing on server
xp.trace_detached(
"localhost:9012", profile_dir, delay_ms=DELAY_MS, duration_ms=DURATION_MS
)
if DELAY_MS == 0:
time.sleep(1.0)
profile_latencies = []
for _ in tqdm(range(args.num_iters), desc="Profile iterations"):
profile_latencies.append(run_to_completion())
print(f"Average profile latency: {np.mean(profile_latencies):.4f}s")
return
def parse_args():
parser = FlexibleArgumentParser(
description="Benchmark the latency of processing a single batch of "
"requests till completion."
)
parser.add_argument("--input-len", type=int, default=32)
parser.add_argument("--output-len", type=int, default=128)
parser.add_argument("--batch-size", type=int, default=8)
parser.add_argument(
"--num-iters-warmup",
type=int,
default=5,
help="Number of iterations to run for warmup.",
)
parser.add_argument(
"--num-iters",
type=int,
default=1,
help="Number of iterations to run for profiling.",
)
parser.add_argument(
"--profile-result-dir",
type=str,
default="profiles",
help=(
"path to save the pytorch profiler output. Can be visualized "
"with ui.perfetto.dev or Tensorboard "
"(https://cloud.google.com/tpu/docs/pytorch-xla-performance-profiling-tpu-vm)."
),
)
parser = EngineArgs.add_cli_args(parser)
return parser.parse_args()
if __name__ == "__main__":
args = parse_args()
main(args)

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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import argparse
import os
from vllm import LLM, SamplingParams
prompts = [
"A robot may not injure a human being",
"It is only with the heart that one can see rightly;",
"The greatest glory in living lies not in never falling,",
]
answers = [
" or, through inaction, allow a human being to come to harm.",
" what is essential is invisible to the eye.",
" but in rising every time we fall.",
]
N = 1
# Currently, top-p sampling is disabled. `top_p` should be 1.0.
sampling_params = SamplingParams(temperature=0, top_p=1.0, n=N, max_tokens=16)
def main():
parser = argparse.ArgumentParser(description="TPU offline inference example")
parser.add_argument("--use-spmd", action="store_true", help="Enable SPMD mode")
args = parser.parse_args()
llm_args = {
"model": "Qwen/Qwen2-1.5B-Instruct",
"max_num_batched_tokens": 64,
"max_num_seqs": 4,
"max_model_len": 128,
}
if args.use_spmd:
os.environ["VLLM_XLA_USE_SPMD"] = "1"
# Can only hardcode the number of chips for now.
# calling xr.global_runtime_device_count() beforeing init SPMD env in
# torch_xla will mess up the distributed env.
llm_args["tensor_parallel_size"] = 8
# Use Llama, for num_kv_heads = 8.
llm_args["model"] = "meta-llama/Llama-3.1-8B-Instruct"
# Set `enforce_eager=True` to avoid ahead-of-time compilation.
# In real workloads, `enforce_eager` should be `False`.
llm = LLM(**llm_args)
outputs = llm.generate(prompts, sampling_params)
print("-" * 50)
for output, answer in zip(outputs, answers):
prompt = output.prompt
generated_text = output.outputs[0].text
print(f"Prompt: {prompt!r}\nGenerated text: {generated_text!r}")
assert generated_text.startswith(answer)
print("-" * 50)
if __name__ == "__main__":
main()