"""Deep profile: why fire-and-forget TTFT is 5x worse than await.""" import json, statistics await_rows = [json.loads(l) for l in open("outputs/gpu_ab_6p2d/metrics.jsonl")] fnf_rows = [json.loads(l) for l in open("outputs/gpu_ab_6p2d_fnf/metrics.jsonl")] await_ok = [r for r in await_rows if not r.get("error")] fnf_ok = [r for r in fnf_rows if not r.get("error")] # Match by request_id await_by_id = {r["request_id"]: r for r in await_ok} fnf_by_id = {r["request_id"]: r for r in fnf_ok} common = set(await_by_id.keys()) & set(fnf_by_id.keys()) print("=" * 75) print(" PROFILE: Fire-and-Forget vs Await-Prefill (same 6P+2D instances)") print("=" * 75) print(f" Common requests: {len(common)}") # Per-request comparison diffs = [] for rid in common: a = await_by_id[rid] f = fnf_by_id[rid] if a.get("ttft_s") and f.get("ttft_s") and a["ttft_s"] > 0: diffs.append({ "id": rid, "input": a["input_length"], "a_ttft": a["ttft_s"], "f_ttft": f["ttft_s"], "ratio": f["ttft_s"] / a["ttft_s"], "a_e2e": a["latency_s"], "f_e2e": f["latency_s"], "a_tpot": a.get("tpot_s", 0), "f_tpot": f.get("tpot_s", 0), "a_out": a.get("actual_output_tokens", 0) or 0, "f_out": f.get("actual_output_tokens", 0) or 0, }) diffs.sort(key=lambda x: x["input"]) print("\n Per-request (sorted by input_length):") hdr = "%8s %10s %10s %7s %10s %10s %8s %8s" % ( "input", "await_TTFT", "fnf_TTFT", "ratio", "await_E2E", "fnf_E2E", "a_TPOT", "f_TPOT") print(" " + hdr) print(" " + "-" * len(hdr)) for d in diffs[:25]: print(" %8d %10.3f %10.3f %6.1fx %10.3f %10.3f %8.4f %8.4f" % ( d["input"], d["a_ttft"], d["f_ttft"], d["ratio"], d["a_e2e"], d["f_e2e"], d["a_tpot"], d["f_tpot"])) # Statistics if diffs: ratios = [d["ratio"] for d in diffs] ratios.sort() p = lambda v, q: v[min(int(q*len(v)), len(v)-1)] print("\n TTFT ratio (FnF / Await):") print(" p10=%.2fx p50=%.2fx p90=%.2fx mean=%.2fx" % ( p(ratios,.1), p(ratios,.5), p(ratios,.9), statistics.fmean(ratios))) faster = sum(1 for r in ratios if r < 1.0) print(" FnF faster: %d/%d (%.0f%%)" % (faster, len(ratios), faster*100/len(ratios))) # Bucket by input size print("\n TTFT ratio by input size bucket:") buckets = [(0, 5000, "<5k"), (5000, 20000, "5-20k"), (20000, 50000, "20-50k"), (50000, 999999, ">50k")] for lo, hi, label in buckets: subset = [d for d in diffs if lo <= d["input"] < hi] if subset: rs = [d["ratio"] for d in subset] a_ttfts = [d["a_ttft"] for d in subset] f_ttfts = [d["f_ttft"] for d in subset] print(" %6s: n=%3d await_TTFT=%.3f fnf_TTFT=%.3f ratio=%.2fx" % ( label, len(subset), statistics.fmean(a_ttfts), statistics.fmean(f_ttfts), statistics.fmean(rs))) # TPOT comparison a_tpots = [d["a_tpot"] for d in diffs if d["a_tpot"] > 0] f_tpots = [d["f_tpot"] for d in diffs if d["f_tpot"] > 0] if a_tpots and f_tpots: print("\n TPOT comparison:") print(" Await: mean=%.4f p50=%.4f" % (statistics.fmean(a_tpots), sorted(a_tpots)[len(a_tpots)//2])) print(" FnF: mean=%.4f p50=%.4f" % (statistics.fmean(f_tpots), sorted(f_tpots)[len(f_tpots)//2])) # Also look at non-common requests (FnF only failures) fnf_err = [r for r in fnf_rows if r.get("error")] await_err_ids = {r["request_id"] for r in await_rows if r.get("error")} fnf_only_err = [r for r in fnf_err if r["request_id"] not in await_err_ids] print("\n Errors unique to FnF: %d" % len(fnf_only_err)) for r in fnf_only_err[:5]: print(" input=%d err=%s" % (r["input_length"], r["error"][:60]))