Files
agentic-pd-hybrid/scripts/smoke_snapshot_link.py
Claude Code Agent dc4867c270 feat(snapshot): D→P RDMA link Phase 1 — minimal byte transport
A thin wrapper around mooncake.engine.TransferEngine that does
one-sided RDMA writes between two SnapshotPeer endpoints. Bypasses
SGLang's MooncakeKVManager (which is hard-gated to PREFILL/DECODE
roles via add_transfer_request assertion at conn.py:1563) so the
D→P direction doesn't require invasive role-axis changes upstream.

Smoke test (two subprocess.Popen processes, mlx5_60, 127.0.0.1):
  1 KB    9.0 ms   (one-time openSegment handshake)
  16 KB   0.04 ms  3.5 Gbps
  1 MB    0.10 ms  82 Gbps
  16 MB   0.58 ms  232 Gbps
  64 MB   1.70 ms  316 Gbps   (~80% of NDR 400G line rate)

All 5 sizes pass SHA256 verification end-to-end.

Files:
  src/agentic_pd_hybrid/snapshot_link.py — SnapshotPeer, SnapshotEndpoint
  scripts/snapshot_link_receiver.py      — child-process receiver
  scripts/smoke_snapshot_link.py         — sender + verifier
  docs/D_TO_P_PHASE1_LINK_ZH.md          — phase 1 acceptance doc

Next: Phase 2 (D-side scheduler commit hook), Phase 3 (P-side prefill
bypass with snapshot KV). See docs/D_TO_P_SYNC_DESIGN_ZH.md §5.
2026-05-13 00:55:55 +08:00

245 lines
8.2 KiB
Python
Executable File

#!/usr/bin/env python3
"""Two-process smoke test for snapshot_link D→P RDMA byte transfer.
Spawns scripts/snapshot_link_receiver.py via subprocess.Popen with stderr
piped to ``<tmpdir>/recv.stderr.log`` for post-mortem if something dies.
Sender (this process):
1. Spawns receiver child, waits for endpoint.json
2. Brings up own SnapshotPeer (no recv buffer), registers a send buffer
3. For each size: fill pattern, batch_transfer_sync_write, signal child,
wait for child's ack
4. Reads child's stdout (one JSON event per line) for verification
Pass = every size yields a child "verify" event with ok=true.
Usage:
bash scripts/setup_env.sh && uv run --no-sync python scripts/smoke_snapshot_link.py
Env (optional):
SNAPSHOT_LINK_HOST default 127.0.0.1
SNAPSHOT_LINK_IB default mlx5_60
SNAPSHOT_LINK_RECV_PORT default 17777
SNAPSHOT_LINK_SEND_PORT default 17778
"""
from __future__ import annotations
import argparse
import ctypes
import hashlib
import json
import os
import subprocess
import sys
import tempfile
import time
from pathlib import Path
_HERE = Path(__file__).resolve().parent
sys.path.insert(0, str(_HERE.parent / "src"))
SIZES_BYTES_DEFAULT = [
1 << 10, # 1 KB
1 << 14, # 16 KB
1 << 18, # 256 KB
1 << 20, # 1 MB
1 << 22, # 4 MB
1 << 24, # 16 MB
1 << 26, # 64 MB
]
def _pattern_byte(i: int, seed: int) -> int:
return (i * 2654435761 + seed) & 0xFF
def _fill_pattern(buf, length: int, seed: int) -> None:
tile_size = 4096
tile = bytes(_pattern_byte(i, seed) for i in range(tile_size))
tile_arr = (ctypes.c_ubyte * tile_size).from_buffer_copy(tile)
n_full = length // tile_size
rem = length - n_full * tile_size
base = ctypes.addressof(buf)
src_addr = ctypes.addressof(tile_arr)
for k in range(n_full):
ctypes.memmove(base + k * tile_size, src_addr, tile_size)
if rem:
ctypes.memmove(base + n_full * tile_size, src_addr, rem)
def main():
ap = argparse.ArgumentParser()
ap.add_argument("--host", default=os.environ.get("SNAPSHOT_LINK_HOST", "127.0.0.1"))
ap.add_argument("--ib", default=os.environ.get("SNAPSHOT_LINK_IB", "mlx5_60"))
ap.add_argument("--recv-port", type=int,
default=int(os.environ.get("SNAPSHOT_LINK_RECV_PORT", "17777")))
ap.add_argument("--send-port", type=int,
default=int(os.environ.get("SNAPSHOT_LINK_SEND_PORT", "17778")))
ap.add_argument("--max-bytes", type=int, default=128 * 1024 * 1024)
ap.add_argument("--sizes", default=",".join(str(s) for s in SIZES_BYTES_DEFAULT))
args = ap.parse_args()
sizes = [int(s) for s in args.sizes.split(",")]
tmpdir = Path(tempfile.mkdtemp(prefix="snapshot_link_smoke_"))
control_path = tmpdir / "endpoint.json"
recv_stderr_log = tmpdir / "recv.stderr.log"
recv_cmd = [
sys.executable,
str(_HERE / "snapshot_link_receiver.py"),
"--host", args.host,
"--port", str(args.recv_port),
"--ib", args.ib,
"--max-bytes", str(args.max_bytes),
"--control-path", str(control_path),
"--sizes", args.sizes,
]
recv_stderr = open(recv_stderr_log, "w")
print(f"[sender] launching receiver: {' '.join(recv_cmd)}", flush=True)
print(f"[sender] receiver stderr → {recv_stderr_log}", flush=True)
recv_proc = subprocess.Popen(
recv_cmd,
stdout=subprocess.PIPE,
stderr=recv_stderr,
bufsize=1,
universal_newlines=True,
)
try:
# Wait for endpoint metadata
deadline = time.time() + 60.0
while time.time() < deadline:
if control_path.exists():
try:
meta = json.loads(control_path.read_text())
if meta.get("ready"):
break
except Exception:
pass
if recv_proc.poll() is not None:
_dump_recv_stderr(recv_stderr_log)
print(f"[sender] FAIL: receiver exited early (rc={recv_proc.returncode})")
return 1
time.sleep(0.1)
else:
print("[sender] FAIL: timed out waiting for receiver endpoint", flush=True)
return 1
print(f"[sender] receiver endpoint: {meta}", flush=True)
from agentic_pd_hybrid.snapshot_link import SnapshotPeer, SnapshotEndpoint
endpoint = SnapshotEndpoint(
session_id=meta["session_id"],
base_ptr=int(meta["base_ptr"]),
capacity_bytes=int(meta["capacity_bytes"]),
)
peer = SnapshotPeer(
host=args.host,
port=args.send_port,
ib_device=args.ib,
receive_capacity_bytes=0,
)
send_buf = (ctypes.c_byte * args.max_bytes)()
send_addr = ctypes.addressof(send_buf)
peer.register_send_buffer(send_addr, args.max_bytes)
print(f"[sender] own session_id={peer.session_id}, send_buf @ {hex(send_addr)} ({args.max_bytes} B)", flush=True)
transfers = []
for size in sizes:
if size > args.max_bytes:
continue
seed = int(time.time() * 1e6) & 0xFFFFFFFF
_fill_pattern(send_buf, size, seed)
t0 = time.perf_counter()
ret = peer.push(endpoint, send_addr, 0, size, remote_offset=0)
t1 = time.perf_counter()
dt_ms = (t1 - t0) * 1000.0
gbps = (size * 8.0 / 1e9) / max(t1 - t0, 1e-9)
print(f"[sender] push size={size:>10d} ret={ret} "
f"dur={dt_ms:>9.3f} ms thru={gbps:>6.3f} Gbps",
flush=True)
signal_path = control_path.with_suffix(f".do{size}")
ack_path = control_path.with_suffix(f".ack{size}")
signal_path.write_text(str(seed))
ack_deadline = time.time() + 60.0
while time.time() < ack_deadline:
if ack_path.exists():
break
if recv_proc.poll() is not None:
print(f"[sender] FAIL: receiver died after size={size}", flush=True)
_dump_recv_stderr(recv_stderr_log)
return 1
time.sleep(0.05)
transfers.append({
"size": size, "ret": ret, "dur_ms": round(dt_ms, 3),
"thru_Gbps": round(gbps, 3),
"ack": ack_path.exists(),
})
peer.close()
# Drain child stdout — each line is a JSON event
try:
recv_proc.wait(timeout=10)
except subprocess.TimeoutExpired:
recv_proc.terminate()
recv_proc.wait(timeout=5)
events = []
if recv_proc.stdout is not None:
for raw in recv_proc.stdout:
raw = raw.strip()
if not raw:
continue
try:
events.append(json.loads(raw))
except json.JSONDecodeError:
events.append({"event": "non-json", "raw": raw})
print("=" * 78)
print("[receiver] events:")
verify_ok = 0
verify_fail = 0
for ev in events:
print(f" {ev}")
if ev.get("event") == "verify":
if ev.get("ok"):
verify_ok += 1
else:
verify_fail += 1
recv_stderr.close()
_dump_recv_stderr(recv_stderr_log, header="--- receiver stderr ---")
overall = "PASS" if verify_fail == 0 and verify_ok == len(transfers) else "FAIL"
print("=" * 78)
print(f"OVERALL: {overall} verify_ok={verify_ok} verify_fail={verify_fail} "
f"transfers={len(transfers)}")
return 0 if overall == "PASS" else 1
finally:
try:
recv_proc.terminate()
recv_proc.wait(timeout=5)
except Exception:
try:
recv_proc.kill()
except Exception:
pass
def _dump_recv_stderr(path: Path, header: str = "--- receiver stderr (last 40) ---") -> None:
try:
text = path.read_text()
except FileNotFoundError:
return
print(header, flush=True)
for line in text.splitlines()[-40:]:
print(f" {line}", flush=True)
if __name__ == "__main__":
sys.exit(main())