Files
agentic-kvc/microbench/fresh_setup/mb2_kv_transfer.py
Gahow Wang 50f72d8875 MB2 inter-node scaffolding: per-host single-instance launcher + client host args
Adds the pieces needed to run the producer on dash1 and the consumer on
dash2 with the same shared cpfs venv:

start_vllm_single.sh
  INSTANCE / GPU / PORT / BP / MASTER / ROLE env vars; brings up ONE
  vLLM instance + applies the mooncake instrumentation patch (idempotent
  since the venv is cpfs-shared, so the first invocation applies and the
  second is a no-op). Per-instance MB2_LOG_DIR keeps producer/consumer
  events separate even though both directories live on the same cpfs
  path visible to both hosts.

mb2_kv_transfer.py
  New --src-host / --dst-host args. Defaults stay 127.0.0.1 for
  backward-compat with the intra-node sweep. /v1/completions URLs and
  /query URLs now use the supplied hosts. remote_bootstrap_addr is
  built as http://<src_host>:<src_bp> so the consumer's
  do_remote_prefill request carries a routable address.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-27 20:26:54 +08:00

262 lines
9.6 KiB
Python
Executable File

#!/usr/bin/env python3
"""MB2: measure KV transfer time between two vLLM instances over Mooncake.
Pattern (adapted from microbench/connector_tax/cache_sweep/smoke_test_migrate_cache.py):
1. Prefill on A: do_remote_decode with max_tokens=1 (A computes & caches KV)
2. Pull to B: do_remote_prefill on B with kv_transfer_params from step 1
(this is the operation that performs the KV transfer)
3. Verify: send a follow-up to B; cached_tokens should equal the
prompt length (confirms the KV landed on B)
We time step 2 — that gives us E2E "transfer + B's prefill check" latency.
By sweeping input_length we trace T_transfer(KV_size).
The follow-up step gives us a sanity check (correctness) but isn't timed.
"""
from __future__ import annotations
import argparse
import asyncio
import json
import statistics
import time
import uuid
from pathlib import Path
import httpx
MODEL_PATH = "/home/admin/cpfs/wjh/models/Qwen/Qwen3-Coder-30B-A3B-Instruct"
async def get_engine_id(client: httpx.AsyncClient, host: str, bootstrap_port: int) -> str:
"""The /query endpoint lives on the mooncake bootstrap port, not the
vLLM HTTP serving port."""
r = await client.get(f"http://{host}:{bootstrap_port}/query")
r.raise_for_status()
data = r.json()
return data["0"]["engine_id"]
async def completion(
client: httpx.AsyncClient,
host: str,
port: int,
prompt_token_ids: list[int],
max_tokens: int,
kv_transfer_params: dict | None = None,
) -> tuple[float, dict]:
payload = {
"model": MODEL_PATH,
"prompt": prompt_token_ids,
"max_tokens": max_tokens,
"min_tokens": max_tokens if max_tokens == 1 else 1,
"temperature": 0.0,
"stream": False,
}
if kv_transfer_params:
payload["kv_transfer_params"] = kv_transfer_params
t0 = time.perf_counter()
r = await client.post(
f"http://{host}:{port}/v1/completions",
json=payload, timeout=600.0,
)
elapsed_s = time.perf_counter() - t0
r.raise_for_status()
return elapsed_s, r.json()
def synth_prompt(rng_seed: int, n_tokens: int) -> list[int]:
"""Deterministic token-id sequence, far enough from special tokens."""
import random
rng = random.Random(rng_seed)
return [rng.randint(100, 150000) for _ in range(n_tokens)]
async def measure_one(
client: httpx.AsyncClient,
src_host: str, src_port: int,
dst_host: str, dst_port: int,
src_eid: str, dst_eid: str,
src_bootstrap_addr: str,
input_tokens: int,
rng_seed: int,
skip_verify: bool = False,
) -> dict:
"""Three-step measurement (step 3 is sanity, optional for strict PD-disagg
where the dst is a kv_consumer-only instance that cannot serve a plain
request).
vLLM-shipped MooncakeConnector kv_transfer_params schema
(vllm/distributed/.../v1/mooncake/mooncake_connector.py:385):
do_remote_decode : {transfer_id}
do_remote_prefill : {transfer_id, remote_engine_id, remote_bootstrap_addr}
"""
prompt = synth_prompt(rng_seed, input_tokens)
session = uuid.uuid4().hex
transfer_id = uuid.uuid4().hex
t_step1_client = time.time()
t_prefill_s, prefill_resp = await completion(
client, src_host, src_port, prompt, max_tokens=1,
kv_transfer_params={
"do_remote_decode": True,
"transfer_id": transfer_id,
},
)
t_step2_client = time.time()
t_transfer_s, pull_resp = await completion(
client, dst_host, dst_port, prompt, max_tokens=1,
kv_transfer_params={
"do_remote_prefill": True,
"transfer_id": transfer_id,
"remote_engine_id": src_eid,
"remote_bootstrap_addr": src_bootstrap_addr,
},
)
t_step2_end_client = time.time()
cached_followup = None
t_followup_s = None
if not skip_verify:
t_followup_s, follow_resp = await completion(
client, dst_host, dst_port, prompt, max_tokens=1,
)
usage = (follow_resp.get("usage") or {})
details = usage.get("prompt_tokens_details") or {}
cached_followup = details.get("cached_tokens", 0) or usage.get("cached_tokens", 0)
pull_usage = (pull_resp.get("usage") or {})
pull_completion_tokens = pull_usage.get("completion_tokens", 0)
ok = pull_completion_tokens >= 1
if not skip_verify and cached_followup is not None:
ok = ok and (cached_followup >= input_tokens * 0.9)
return {
"input_tokens": input_tokens,
"session": session,
"t_step1_client_unix": t_step1_client,
"t_step2_client_unix": t_step2_client,
"t_step2_end_unix": t_step2_end_client,
"t_prefill_s": t_prefill_s,
"t_transfer_s": t_transfer_s,
"t_followup_s": t_followup_s,
"cached_followup": cached_followup,
"pull_completion_tokens": pull_completion_tokens,
"ok": ok,
}
async def main_async(args: argparse.Namespace) -> None:
sizes_str = args.sizes
sizes = [int(s) for s in sizes_str.split(",")]
repeats = args.repeats
src_host, dst_host = args.src_host, args.dst_host
src_port, dst_port = args.src_port, args.dst_port
src_bp, dst_bp = args.src_bp, args.dst_bp
limits = httpx.Limits(max_connections=10, max_keepalive_connections=10)
async with httpx.AsyncClient(limits=limits, trust_env=False) as client:
src_eid = await get_engine_id(client, src_host, src_bp)
try:
dst_eid = await get_engine_id(client, dst_host, dst_bp)
except Exception as exc:
print(f"[mb2] dst bootstrap ({dst_host}:{dst_bp}) unreachable ({exc.__class__.__name__}); "
f"running in strict-PD mode (dst is kv_consumer, no bootstrap).")
dst_eid = None
print(f"[mb2] src={src_host}:{src_port} bp={src_bp} eid={src_eid[:16]}...")
print(f"[mb2] dst={dst_host}:{dst_port} bp={dst_bp} eid="
f"{(dst_eid[:16] + '...') if dst_eid else 'N/A (kv_consumer)'}")
src_bootstrap_addr = f"http://{src_host}:{src_bp}"
results = []
for sz in sizes:
for r in range(repeats):
row = await measure_one(
client,
src_host, src_port, dst_host, dst_port,
src_eid, dst_eid,
src_bootstrap_addr=src_bootstrap_addr,
input_tokens=sz, rng_seed=sz * 1000 + r,
skip_verify=args.skip_verify,
)
cached = row.get("cached_followup")
cached_str = f"{cached}/{sz}" if cached is not None else "skip"
print(f" size={sz:>6} rep={r} "
f"transfer={row['t_transfer_s']*1000:7.1f}ms "
f"followup_cached={cached_str} "
f"ok={row['ok']}")
results.append(row)
# Summarise per-size
summary = []
for sz in sizes:
ts = [r["t_transfer_s"] for r in results if r["input_tokens"] == sz and r["ok"]]
if not ts:
continue
summary.append({
"input_tokens": sz,
"n_ok": len(ts),
"transfer_s_mean": statistics.mean(ts),
"transfer_s_p50": statistics.median(ts),
"transfer_s_p90": statistics.quantiles(ts, n=10)[-1] if len(ts) >= 10 else max(ts),
"transfer_s_min": min(ts),
"transfer_s_max": max(ts),
})
out = {
"model": MODEL_PATH,
"kv_bytes_per_token": 98304,
"src_host": src_host,
"src_port": src_port,
"dst_host": dst_host,
"dst_port": dst_port,
"config_label": args.label,
"raw": results,
"summary": summary,
}
Path(args.out).write_text(json.dumps(out, indent=2))
print(f"[mb2] wrote {args.out}")
for s in summary:
sz = s["input_tokens"]
kv_mib = sz * 98304 / 1024 / 1024
print(f" {sz:>6} tok ({kv_mib:>7.1f} MiB KV): "
f"mean {s['transfer_s_mean']*1000:7.1f} ms · "
f"p50 {s['transfer_s_p50']*1000:7.1f} · "
f"p90 {s['transfer_s_p90']*1000:7.1f} "
f"(n_ok={s['n_ok']})")
def main() -> None:
p = argparse.ArgumentParser()
p.add_argument("--src-host", default="127.0.0.1",
help="hostname/IP of the producer (A); use a routable "
"address for inter-node tests")
p.add_argument("--dst-host", default="127.0.0.1",
help="hostname/IP of the consumer (B)")
p.add_argument("--src-port", type=int, default=8000,
help="vLLM HTTP port on the producer side (A)")
p.add_argument("--dst-port", type=int, default=8001,
help="vLLM HTTP port on the consumer side (B)")
p.add_argument("--src-bp", type=int, default=8998,
help="Mooncake bootstrap port on A (serves /query)")
p.add_argument("--dst-bp", type=int, default=8999,
help="Mooncake bootstrap port on B (serves /query)")
p.add_argument(
"--sizes",
default="512,1024,2048,4096,8192,16384,32768,65536",
help="Comma-separated input_token sizes to sweep",
)
p.add_argument("--repeats", type=int, default=5)
p.add_argument("--label", default="intra-node",
help="Label written into the output (e.g. intra-node / inter-node)")
p.add_argument("--out", default="mb2_result.json")
p.add_argument("--skip-verify", action="store_true",
help="Skip the step-3 verify completion (required for "
"strict PD-disagg where dst is kv_consumer-only).")
args = p.parse_args()
asyncio.run(main_async(args))
if __name__ == "__main__":
main()