vllm/examples/offline_inference/cpu_offload_lmcache.py
Chauncey 7a4a5de729
[Misc] Update outdated note: LMCache now supports chunked prefill (#16697)
Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>
2025-04-18 05:12:42 +00:00

101 lines
3.0 KiB
Python

# SPDX-License-Identifier: Apache-2.0
"""
This file demonstrates the example usage of cpu offloading
with LMCache.
Note that `lmcache` is needed to run this example.
Requirements: Linux, Python: 3.10 or higher, CUDA: 12.1
Learn more about LMCache environment setup, please refer to:
https://docs.lmcache.ai/getting_started/installation.html
"""
import contextlib
import os
import time
from lmcache.experimental.cache_engine import LMCacheEngineBuilder
from lmcache.integration.vllm.utils import ENGINE_NAME
from vllm import LLM, SamplingParams
from vllm.config import KVTransferConfig
def setup_environment_variables():
# LMCache-related environment variables
# Use experimental features in LMCache
os.environ["LMCACHE_USE_EXPERIMENTAL"] = "True"
# LMCache is set to use 256 tokens per chunk
os.environ["LMCACHE_CHUNK_SIZE"] = "256"
# Enable local CPU backend in LMCache
os.environ["LMCACHE_LOCAL_CPU"] = "True"
# Set local CPU memory limit to 5.0 GB
os.environ["LMCACHE_MAX_LOCAL_CPU_SIZE"] = "5.0"
@contextlib.contextmanager
def build_llm_with_lmcache():
ktc = KVTransferConfig.from_cli(
'{"kv_connector":"LMCacheConnector", "kv_role":"kv_both"}')
# Set GPU memory utilization to 0.8 for an A40 GPU with 40GB
# memory. Reduce the value if your GPU has less memory.
# Note: LMCache supports chunked prefill (see vLLM#14505, LMCache#392).
llm = LLM(model="mistralai/Mistral-7B-Instruct-v0.2",
kv_transfer_config=ktc,
max_model_len=8000,
enable_chunked_prefill=True,
gpu_memory_utilization=0.8)
try:
yield llm
finally:
# Clean up lmcache backend
LMCacheEngineBuilder.destroy(ENGINE_NAME)
def print_output(
llm: LLM,
prompt: list[str],
sampling_params: SamplingParams,
req_str: str,
):
start = time.time()
outputs = llm.generate(prompt, sampling_params)
print("-" * 50)
for output in outputs:
generated_text = output.outputs[0].text
print(f"Generated text: {generated_text!r}")
print(f"Generation took {time.time() - start:.2f} seconds, "
f"{req_str} request done.")
print("-" * 50)
def main():
setup_environment_variables()
with build_llm_with_lmcache() as llm:
# This example script runs two requests with a shared prefix.
# Define the shared prompt and specific prompts
shared_prompt = "Hello, how are you?" * 1000
first_prompt = [
shared_prompt + "Hello, my name is",
]
second_prompt = [
shared_prompt + "Tell me a very long story",
]
sampling_params = SamplingParams(temperature=0,
top_p=0.95,
max_tokens=10)
# Print the first output
print_output(llm, first_prompt, sampling_params, "first")
time.sleep(1)
# print the second output
print_output(llm, second_prompt, sampling_params, "second")
if __name__ == "__main__":
main()