Files
agentic-kvc/scripts/b3_isolated_policy.sh
Gahow Wang 19f69a9d2e unified_v2: selective per-request PD-sep via Mooncake (E3+E4)
Adds a sixth routing policy --policy unified_v2 that wraps the
existing unified hybrid picker with a selective PD-sep branch.
When all of the following hold, a request is split prefill-on-src,
decode-on-chosen via Mooncake kv_role=kv_both transfer:

  1. new_local = input_length - chosen.cache_hit > 16k
     (B2 microbench shows same-worker TTFT idx >= 3x from this size up)
  2. chosen has live decodes worth protecting (>= 2 in-flight)
  3. some other instance holds materially more cache for this prefix
     (>= 8k tokens, and >= 4k more than chosen)
  4. cost(src_interference + RDMA xfer) + 0.2s margin < cost(chosen_interference)

The cost model is the audit-blessed shape from E1's post-mortem:
- gate on new_tokens (post-cache), NOT input_length (the old PUSH gate)
- bind to a single transfer mechanism (kv_both peer-to-peer pull)
- realistic RDMA cost as a function of bytes: 0.3s base +
  bytes / 2.7 GB/s (calibrated against contention_16s_elastic p50)
- both source and target decode counts considered

E2 mechanism-level patches not yet applied (this commit is policy-only).
Patches 6.2 / 6.3 / 6.5 remain on the table. Patch 6.6 (per-request
xfer timeout, 60s default) is implemented on the proxy side as an
httpx per-chunk read timeout on the dst streaming call, so a stuck
KV transfer fails the request instead of hanging for 600s.

cache_aware_proxy.py:
- Settings: kv_bytes_per_token, prefill_throughput_kv_both,
  rdma_base_overhead_s, rdma_effective_gb_per_s, pd_sep_* gating knobs
- estimate_transfer_cost(bytes) replaces the constant rdma_overhead_s
- estimate_same_worker_interference_s(new_tokens, num_decodes) reads off
  the B2 penalty curve in 4 bins
- pick_instance_unified_v2: inherits unified, returns extra
  (src_inst, src_idx) tuple when PD-sep wins the cost compare
- _handle_combined_pd_sep_v2: prefill on src (do_remote_decode=True,
  max_tokens=1), Mooncake xfer, decode-stream on dst with httpx
  Timeout(read=pd_sep_xfer_timeout_s)
- --policy unified_v2 added to argparse choices
- lifespan auto-runs init_prefill_bootstrap when policy is unified_v2

b3_isolated_policy.sh:
- ENABLE_KV_BOTH env var, auto-set when POLICY=unified_v2, threads
  kv_role=kv_both + VLLM_MOONCAKE_BOOTSTRAP_PORT to vllm and
  --bootstrap-ports to the proxy

Tests: 8 new unit tests cover the gating predicates and the cost
estimators; all 32 proxy tests still pass.

Refs: E1 (PUSH post-mortem) + E2 (Mooncake audit) reports.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-26 09:25:45 +08:00

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#!/usr/bin/env bash
# Run a single B3 policy with a cold-start vLLM (clean APC).
#
# Usage:
# bash scripts/b3_isolated_policy.sh <policy> <trace> <rundir>
#
# Launches 8 fresh vLLM instances, captures their engine_state into
# <rundir>/engine_state/, runs the policy through the proxy on
# <trace>, then kills everything. Distinct from b3_sweep.sh which
# shares one vLLM-set across all five policies (faster but warm-cache).
set -euo pipefail
ROOT="${ROOT:-/home/admin/cpfs/wjh/agentic-kv}"
VENV="$ROOT/.venv/bin"
MODEL="${MODEL:-/home/admin/cpfs/wjh/models/Qwen/Qwen3-Coder-30B-A3B-Instruct}"
PROXY_PORT="${PROXY_PORT:-9300}"
BASE_PORT="${BASE_PORT:-8000}"
GPU_INDICES="${GPU_INDICES:-0 1 2 3 4 5 6 7}"
EXTRA_VLLM_ARGS="${EXTRA_VLLM_ARGS:---enable-prompt-tokens-details}"
N_INSTANCES=$(echo $GPU_INDICES | wc -w)
# When ENABLE_KV_BOTH=1, vLLM launches with the Mooncake KV connector in
# kv_both role and the proxy is given bootstrap ports. This is required
# for --policy unified_v2 (per-request PD-sep) but disabled by default
# because it adds always-on KV-transfer overhead even when not triggered.
ENABLE_KV_BOTH="${ENABLE_KV_BOTH:-0}"
BOOTSTRAP_BASE_PORT="${BOOTSTRAP_BASE_PORT:-8998}"
POLICY="${1:?usage: $0 <policy> <trace> <rundir>}"
TRACE="${2:?usage: $0 <policy> <trace> <rundir>}"
RUNDIR="${3:?usage: $0 <policy> <trace> <rundir>}"
# Auto-enable kv_both when the policy requires it.
if [ "$POLICY" = "unified_v2" ]; then
ENABLE_KV_BOTH=1
fi
mkdir -p "$RUNDIR/engine_state" "$RUNDIR/logs"
echo "[isolated] policy=$POLICY trace=$(basename $TRACE) rundir=$RUNDIR"
cleanup() {
pkill -9 -f cache_aware_proxy 2>/dev/null || true
pkill -9 -f "vllm serve" 2>/dev/null || true
pkill -9 -f "EngineCore" 2>/dev/null || true
sleep 3
}
trap cleanup EXIT
# Hard reset first
cleanup
echo "[isolated] launching $N_INSTANCES vLLM on GPUs $GPU_INDICES ENABLE_KV_BOTH=$ENABLE_KV_BOTH ..."
i=0
kv_both_extra=""
if [ "$ENABLE_KV_BOTH" = "1" ]; then
kv_both_extra="--kv-transfer-config {\"kv_connector\":\"MooncakeConnector\",\"kv_role\":\"kv_both\"}"
fi
for gpu in $GPU_INDICES; do
port=$((BASE_PORT + i))
master=$((29500 + i))
bp=$((BOOTSTRAP_BASE_PORT + i))
if [ "$ENABLE_KV_BOTH" = "1" ]; then
PYTHONHASHSEED=42 \
VLLM_MOONCAKE_BOOTSTRAP_PORT=$bp \
AGENTIC_STEP_LOG_PATH="$RUNDIR/engine_state/engine_${i}.jsonl" \
AGENTIC_WORKER_ID="engine_${i}" \
CUDA_VISIBLE_DEVICES=$gpu \
MASTER_PORT=$master \
nohup "$VENV/vllm" serve "$MODEL" \
--host 0.0.0.0 --port "$port" \
--tensor-parallel-size 1 \
--trust-remote-code --enable-prefix-caching \
--dtype auto --gpu-memory-utilization 0.9 \
--max-model-len 200000 \
--kv-transfer-config '{"kv_connector":"MooncakeConnector","kv_role":"kv_both"}' \
$EXTRA_VLLM_ARGS \
> "$RUNDIR/logs/vllm_inst_${i}_gpu${gpu}.log" 2>&1 &
else
AGENTIC_STEP_LOG_PATH="$RUNDIR/engine_state/engine_${i}.jsonl" \
AGENTIC_WORKER_ID="engine_${i}" \
CUDA_VISIBLE_DEVICES=$gpu \
MASTER_PORT=$master \
nohup "$VENV/vllm" serve "$MODEL" \
--host 0.0.0.0 --port "$port" \
--tensor-parallel-size 1 \
--trust-remote-code --enable-prefix-caching \
--dtype auto --gpu-memory-utilization 0.9 \
--max-model-len 200000 \
$EXTRA_VLLM_ARGS \
> "$RUNDIR/logs/vllm_inst_${i}_gpu${gpu}.log" 2>&1 &
fi
disown
sleep 2
i=$((i + 1))
done
echo "[isolated] waiting for vLLM health ..."
for i in $(seq 0 $((N_INSTANCES - 1))); do
port=$((BASE_PORT + i))
tries=0
while ! curl -sf "http://127.0.0.1:$port/health" >/dev/null 2>&1; do
tries=$((tries + 1))
if [ $tries -gt 90 ]; then
echo "[isolated] FATAL: inst_$i not healthy after 180s"
exit 1
fi
sleep 2
done
echo " inst_$i ready"
done
echo "[isolated] launching proxy with --policy $POLICY ..."
combined_args=""
for i in $(seq 0 $((N_INSTANCES - 1))); do
combined_args="$combined_args http://127.0.0.1:$((BASE_PORT + i))"
done
proxy_extra=""
if [ "$ENABLE_KV_BOTH" = "1" ]; then
bp_list=""
for i in $(seq 0 $((N_INSTANCES - 1))); do
if [ -z "$bp_list" ]; then
bp_list="$((BOOTSTRAP_BASE_PORT + i))"
else
bp_list="$bp_list,$((BOOTSTRAP_BASE_PORT + i))"
fi
done
proxy_extra="--bootstrap-ports $bp_list"
fi
nohup "$VENV/python" "$ROOT/scripts/cache_aware_proxy.py" \
--port "$PROXY_PORT" \
--combined $combined_args \
--policy "$POLICY" \
$proxy_extra \
> "$RUNDIR/proxy.log" 2>&1 &
disown
tries=0
until curl -sf "http://127.0.0.1:$PROXY_PORT/stats" >/dev/null 2>&1; do
tries=$((tries + 1))
if [ $tries -gt 30 ]; then
echo "[isolated] FATAL: proxy did not come up in 60s"
tail -30 "$RUNDIR/proxy.log"
exit 1
fi
sleep 2
done
t_start=$(date +%s.%N)
echo "[isolated] running replayer ..."
PYTHONPATH="$ROOT" "$VENV/python" -m replayer \
--trace "$TRACE" \
--output "$RUNDIR/metrics.jsonl" \
--endpoint "http://127.0.0.1:$PROXY_PORT" \
--model "$MODEL" \
2>&1 | tee "$RUNDIR/replayer.log" | tail -3
t_end=$(date +%s.%N)
python3 - "$RUNDIR" "$POLICY" "$TRACE" "$t_start" "$t_end" <<'PY'
import json, sys
rundir, policy, trace, t_start, t_end = sys.argv[1:]
with open(f"{rundir}/run_window.json", "w") as f:
json.dump({
"policy": policy, "trace": trace,
"t_start_unix": float(t_start),
"t_end_unix": float(t_end),
"isolated": True,
}, f, indent=2)
PY
curl -s "http://127.0.0.1:$PROXY_PORT/breakdown" > "$RUNDIR/breakdown.json"
curl -s "http://127.0.0.1:$PROXY_PORT/worker_state" > "$RUNDIR/worker_state.json"
curl -s "http://127.0.0.1:$PROXY_PORT/stats" > "$RUNDIR/stats.json"
echo "[isolated] $POLICY done: $(wc -l < "$RUNDIR/metrics.jsonl") metric rows"