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vllm-omni/.claude/skills/diffusion-perf-opt/scripts/trace_analyzer.py
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2026-05-18 00:59:46 +08:00

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Python
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#!/usr/bin/env python3
"""Summarize torch profiler Chrome traces for vLLM Omni diffusion optimization."""
from __future__ import annotations
import argparse
import collections
import gzip
import json
from pathlib import Path
from typing import Any
GPU_CATS = {"kernel", "gpu_memcpy", "gpu_memset"}
CPU_CATS = {"python_function", "user_annotation", "cpu_op", "cuda_runtime", "cuda_driver"}
def open_trace(path: Path):
if path.suffix == ".gz":
return gzip.open(path, "rt")
return path.open("rt")
def event_name(event: dict[str, Any]) -> str:
return str(event.get("name", ""))
def summarize_trace(path: Path, min_gap_us: float, topn: int) -> None:
with open_trace(path) as f:
data = json.load(f)
events = data if isinstance(data, list) else data.get("traceEvents", [])
gpu: list[tuple[float, float, float, str, str, Any, Any]] = []
cpu: list[tuple[float, float, float, str, str, Any, Any]] = []
by_gpu_name: dict[str, list[float]] = collections.defaultdict(lambda: [0, 0.0, 0.0])
by_name: dict[str, list[float]] = collections.defaultdict(lambda: [0, 0.0, 0.0])
nccl: dict[tuple[str, str], list[float]] = collections.defaultdict(lambda: [0, 0.0, 0.0])
for event in events:
dur = event.get("dur")
ts = event.get("ts")
if dur is None or ts is None or dur <= 0:
continue
cat = str(event.get("cat", ""))
name = event_name(event)
row = (float(ts), float(ts + dur), float(dur), name, cat, event.get("pid"), event.get("tid"))
stat = by_name[name]
stat[0] += 1
stat[1] += dur
stat[2] = max(stat[2], dur)
if cat in GPU_CATS:
gpu.append(row)
gstat = by_gpu_name[name]
gstat[0] += 1
gstat[1] += dur
gstat[2] = max(gstat[2], dur)
elif cat in CPU_CATS:
cpu.append(row)
if "nccl" in name.lower():
nstat = nccl[(cat, name)]
nstat[0] += 1
nstat[1] += dur
nstat[2] = max(nstat[2], dur)
print(f"\n== {path}")
print(f"events={len(events)} gpu_events={len(gpu)} cpu_events={len(cpu)}")
if not gpu:
print("No GPU events found.")
return
gpu.sort()
merged: list[list[Any]] = []
for start, end, dur, name, cat, pid, tid in gpu:
if not merged or start > merged[-1][1]:
merged.append([start, end, [(start, end, dur, name, cat, pid, tid)]])
else:
merged[-1][1] = max(merged[-1][1], end)
merged[-1][2].append((start, end, dur, name, cat, pid, tid))
span = max(end for _, end, *_ in gpu) - min(start for start, *_ in gpu)
busy = sum(end - start for start, end, _ in merged)
idle = span - busy
print(
f"gpu_span_s={span / 1e6:.3f} "
f"busy_union_s={busy / 1e6:.3f} "
f"idle_union_s={idle / 1e6:.3f} "
f"idle_pct={idle / span * 100:.2f}"
)
interesting_cpu = [
row
for row in cpu
if row[2] >= 1000
and (
row[4] in {"python_function", "user_annotation"}
or "cudaStreamSynchronize" in row[3]
or "cudaDeviceSynchronize" in row[3]
or "cudaLaunch" in row[3]
or "cudaMemcpy" in row[3]
)
]
gaps = []
for idx in range(1, len(merged)):
gap_start = merged[idx - 1][1]
gap_end = merged[idx][0]
gap_dur = gap_end - gap_start
if gap_dur >= min_gap_us:
prev_event = max(merged[idx - 1][2], key=lambda x: x[1])
next_event = min(merged[idx][2], key=lambda x: x[0])
mid = (gap_start + gap_end) / 2
containers = [row for row in interesting_cpu if row[0] <= mid <= row[1]]
containers = sorted(containers, key=lambda x: x[2])[:8]
gaps.append((gap_dur, gap_start, gap_end, prev_event, next_event, containers))
print(f"gaps_ge_{min_gap_us / 1000:.3f}ms count={len(gaps)} sum_s={sum(g[0] for g in gaps) / 1e6:.3f}")
for gap_dur, gap_start, gap_end, prev_event, next_event, containers in sorted(gaps, reverse=True)[:topn]:
print(f"\nGAP {gap_dur / 1000:.3f} ms ts={gap_start:.0f}->{gap_end:.0f}")
print(f" prev {prev_event[4]} {prev_event[2] / 1000:.3f} ms {prev_event[3][:160]}")
print(f" next {next_event[4]} {next_event[2] / 1000:.3f} ms {next_event[3][:160]}")
for row in containers:
print(f" in {row[4]} {row[2] / 1000:.3f} ms {row[3][:180]}")
print("\nTop GPU/operator events by total duration:")
for name, (count, total, max_dur) in sorted(by_gpu_name.items(), key=lambda kv: kv[1][1], reverse=True)[:topn]:
print(f" {int(count):8d} total={total / 1e6:9.3f}s max={max_dur / 1000:9.3f}ms {name[:180]}")
print("\nTop NCCL-like events by category:")
for (cat, name), (count, total, max_dur) in sorted(nccl.items(), key=lambda kv: kv[1][1], reverse=True)[:topn]:
print(f" {int(count):8d} total={total / 1e6:9.3f}s max={max_dur / 1000:9.3f}ms cat={cat} {name[:160]}")
def main() -> None:
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument("traces", nargs="+", type=Path, help="trace.json or trace.json.gz files")
parser.add_argument("--min-gap-ms", type=float, default=5.0, help="minimum GPU idle gap to print")
parser.add_argument("--topn", type=int, default=20, help="number of gaps/hotspots to print")
args = parser.parse_args()
for trace in args.traces:
summarize_trace(trace, args.min_gap_ms * 1000.0, args.topn)
if __name__ == "__main__":
main()