Files
vllm-omni/baselines/llama_cpp/cmp_llamacpp.py
T
tzhouamandClaude Opus 5 9264ff81ab Include the baselines, comparisons and study documents, not just the fork
The packaging commit shipped the code and a summary of the numbers. It left out
everything the numbers are measured *against*, which is most of what makes them
checkable.

Added:

  baselines/                 llama.cpp runs (thread sweeps, NUMA sweeps, the
                             interleaved A/B passes behind the headline decode
                             figure) and the quality references: each build
                             against its own bf16 over 12 greedy prompts.
  benchmarks/.../results/    102 artifacts backing the published figures, each
                             with a provenance block naming the model,
                             quantization, thread set and build SHAs.
  docs/engines/              the engine analyses -- llama.cpp, ExecuTorch, MNN,
                             ncnn, vLLM, vLLM-Omni -- and the cross-engine and
                             device-simulation comparisons.
  docs/analysis/             the full study documents the summaries distil.
  docs/edge/comparisons.md   where this fork sits against llama.cpp and why:
                             decode is llama.cpp's, prefill is ours by ~2x, and
                             since neither engine exceeds 39% of the measured
                             222 GB/s ceiling the decode gap is the execution
                             model rather than the kernels.
  docs/edge/environment.md   pins and machine, and the correction below.

On "the modified vllm": there isn't one, and the doc says so plainly because it
is the obvious assumption. The vLLM checkout is clean upstream (0 commits
ahead, 0 uncommitted) and the installed wheel is stock 0.28.0+cpu. This fork
changes vLLM's CPU *behaviour* through vLLM's own extension points at import
time -- three CPU patches in vllm_omni/patch.py, the quantization-config
registry, the IR op registry, platform hooks -- specifically so the changes
survive a wheel upgrade rather than being lost on it. One of those patches is
why "KV sizing is not a memory lever" looked true for months: CpuPlatform
overwrote kv_cache_memory_bytes unconditionally, so the setting had no effect.
There is no patch series to apply; pin the version and let patch.py do the rest.

.gitignore gains explicit exceptions: upstream's blanket `*.json` and `results/`
rules were silently eating the measurement artifacts, which in this fork are the
substance rather than build output. Binary captures stay ignored.

No vLLM or llama.cpp source is redistributed -- only output produced with them.
NOTICE records both.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L1ax5wYLA6XbqEL1i8L9gZ
2026-09-14 14:01:12 +08:00

107 lines
4.1 KiB
Python

"""Greedy-decode parity for llama.cpp against the same fp32 reference vLLM is
scored on.
The point of the comparison is that "4-bit" is not one thing: llama.cpp's
Q4_K_M and our `cpu_int4` spend a similar number of bits per weight but pick
different grids, so the speed comparison is only meaningful next to a quality
comparison run on identical prompts. llama-server takes a prompt as raw token
ids, so both engines see exactly the token sequence the reference did.
"""
import argparse, json, subprocess, time, urllib.request
import numpy as np
def post(url, payload, timeout=600):
req = urllib.request.Request(
url, data=json.dumps(payload).encode(),
headers={"Content-Type": "application/json"})
with urllib.request.urlopen(req, timeout=timeout) as r:
return json.loads(r.read())
def main():
ap = argparse.ArgumentParser()
ap.add_argument("--gguf", required=True)
ap.add_argument("--ref", default="ref.json")
ap.add_argument("--ref-logits", default="ref_logits.npy")
ap.add_argument("--bin", default="/data/zhoutaichang/embedding_infer/llama.cpp/build/bin/llama-server")
ap.add_argument("--cores", default="56-87")
ap.add_argument("--threads", type=int, default=32)
ap.add_argument("--port", type=int, default=18099)
ap.add_argument("--ctx", type=int, default=4096)
ap.add_argument("--out", default="parity_llamacpp.json")
a = ap.parse_args()
ref = json.load(open(a.ref))
ref_logits = np.load(a.ref_logits)
n_new = len(ref["new_ids"])
proc = subprocess.Popen(
["taskset", "-c", a.cores, a.bin, "-m", a.gguf, "--port", str(a.port),
"-t", str(a.threads), "-c", str(a.ctx), "--no-warmup", "--host", "127.0.0.1"],
stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
url = f"http://127.0.0.1:{a.port}"
try:
for _ in range(180):
try:
urllib.request.urlopen(url + "/health", timeout=2)
break
except Exception:
time.sleep(1)
else:
raise RuntimeError("llama-server did not become healthy")
res = post(url + "/completion", {
"prompt": ref["prompt_ids"], "n_predict": n_new,
"temperature": 0.0, "top_k": 1, "n_probs": 20,
"cache_prompt": False, "post_sampling_probs": False,
})
finally:
proc.terminate()
try:
proc.wait(timeout=30)
except subprocess.TimeoutExpired:
proc.kill()
probs = res.get("completion_probabilities") or []
ids = [p["id"] for p in probs] if probs and "id" in probs[0] else []
n = min(n_new, len(ids)) if ids else 0
match = sum(int(x == y) for x, y in zip(ref["new_ids"][:n], ids[:n]))
rep = {
"engine": "llama.cpp", "gguf": a.gguf.split("/")[-1],
"ref_text": ref["text"], "llamacpp_text": res.get("content", ""),
"greedy_token_match": f"{match}/{n}" if n else "n/a",
"exact_match": bool(n) and ref["new_ids"][:n] == ids[:n],
"ref_top1": ref["top1"],
"llamacpp_first_token": ids[0] if ids else None,
"first_token_agree": bool(ids) and ids[0] == ref["top1"],
}
if probs:
import math
top = (probs[0].get("top_logprobs") or probs[0].get("top_probs")
or probs[0].get("probs") or [])
first = {}
for e in top:
if "id" not in e:
continue
first[int(e["id"])] = (float(e["prob"]) if "prob" in e
else math.exp(float(e["logprob"])))
ref_top = np.argsort(-ref_logits)[:20]
ref_p = np.exp(ref_logits - ref_logits.max())
ref_p /= ref_p.sum()
pairs = [(int(t), float(ref_p[t]), first[int(t)]) for t in ref_top if int(t) in first]
rep["top20_prob_overlap"] = f"{len(pairs)}/20"
if pairs:
d = [abs(r - v) for _, r, v in pairs]
rep["top20_prob_max_abs_diff"] = max(d)
rep["top20_prob_mean_abs_diff"] = sum(d) / len(d)
print(json.dumps(rep, indent=2, ensure_ascii=False))
with open(a.out, "w") as f:
json.dump(rep, f, indent=2, ensure_ascii=False)
if __name__ == "__main__":
main()