Files
agentic-pd-hybrid/scripts/snapshot_link_receiver.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

124 lines
3.8 KiB
Python

#!/usr/bin/env python3
"""Receiver-side child process for the snapshot_link smoke test.
Reads CLI args, brings up a SnapshotPeer with a registered recv buffer,
writes endpoint metadata to a control file, then loops: wait for size
signal, verify recv buffer, write ack.
Status events are printed as single-line JSON to stdout for parent to
parse.
"""
from __future__ import annotations
import argparse
import ctypes
import hashlib
import json
import sys
import time
from pathlib import Path
sys.path.insert(0, str(Path(__file__).resolve().parent.parent / "src"))
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 _emit(d: dict) -> None:
print(json.dumps(d), flush=True)
def main():
ap = argparse.ArgumentParser()
ap.add_argument("--host", required=True)
ap.add_argument("--port", type=int, required=True)
ap.add_argument("--ib", required=True)
ap.add_argument("--max-bytes", type=int, required=True)
ap.add_argument("--control-path", required=True)
ap.add_argument("--sizes", required=True, help="comma-separated bytes")
args = ap.parse_args()
sizes = [int(s) for s in args.sizes.split(",")]
from agentic_pd_hybrid.snapshot_link import SnapshotPeer
try:
peer = SnapshotPeer(
host=args.host,
port=args.port,
ib_device=args.ib,
receive_capacity_bytes=args.max_bytes,
)
except Exception as e:
import traceback
_emit({"event": "init-failed", "error": repr(e), "tb": traceback.format_exc()})
sys.exit(2)
endpoint = peer.endpoint
Path(args.control_path).write_text(json.dumps({
"session_id": endpoint.session_id,
"base_ptr": endpoint.base_ptr,
"capacity_bytes": endpoint.capacity_bytes,
"ready": True,
}))
_emit({"event": "endpoint-ready", "session_id": endpoint.session_id,
"base_ptr": endpoint.base_ptr, "capacity": endpoint.capacity_bytes})
cp = Path(args.control_path)
for size in sizes:
if size > args.max_bytes:
continue
signal_path = cp.with_suffix(f".do{size}")
ack_path = cp.with_suffix(f".ack{size}")
deadline = time.time() + 120.0
while time.time() < deadline:
if signal_path.exists():
break
time.sleep(0.05)
else:
_emit({"event": "no-signal-timeout", "size": size})
continue
try:
seed = int(signal_path.read_text().strip())
except Exception as e:
_emit({"event": "signal-parse-error", "size": size, "err": repr(e)})
continue
expected_arr = (ctypes.c_ubyte * size)()
_fill_pattern(expected_arr, size, seed)
expected_hash = hashlib.sha256(bytes(expected_arr)).hexdigest()
recv_bytes = peer.read_bytes(0, size)
recv_hash = hashlib.sha256(recv_bytes).hexdigest()
ok = recv_hash == expected_hash
_emit({
"event": "verify",
"size": size,
"ok": ok,
"expected_sha": expected_hash[:16],
"got_sha": recv_hash[:16],
"first8_recv": recv_bytes[:8].hex(),
"last8_recv": recv_bytes[-8:].hex(),
})
ack_path.write_text("done")
peer.close()
_emit({"event": "receiver-done"})
if __name__ == "__main__":
main()