onnx_benchy

onnx_benchy measures how fast an ONNX text-embedding model runs

onnx_benchy model.onnx --tokenizer BAAI/bge-small-en-v1.5
onnx_benchy model.onnx --tokenizer ./my-tokenizer/ --cuda --cpu \
  --batch-size 16 --context-size 512 --tokens 500000 --minutes 2

Install

pip install onnx-benchy            # CPU build
pip install "onnx-benchy[cuda]"    # GPU build, in a separate venv

From source, for development:

git clone https://github.com/electroglyph/onnx_benchy
cd onnx_benchy
pip install -e .          # CPU build
pip install -e ".[cuda]"  # GPU build, in a separate venv

Options

Model and tokenizer

• model — path to the .onnx file.
• --tokenizer (required) — local directory or Hugging Face id, e.g. ./tok/ or BAAI/bge-small-en-v1.5. An ONNX file doesn't include a tokenizer, so there is no default here.
• --config-dir — directory with modules.json and *Pooling/config.json, used to detect pooling and normalization settings. Default: the folder the model file is in.
• --list-outputs — print the model's output names, shapes, and dtypes, then exit. Handy for figuring out what --output should point at.

Backends

One flag per backend: --cpu, --cuda, --tensorrt, --rocm, --migraphx, --openvino, --coreml, --directml, --qnn.

• If you pass none of them, every supported backend available on the machine is benchmarked.

Batch shape

• --batch-size (default 16) — sequences per inference request. Latency is reported per document (batch time divided by batch size), so it's comparable across batch sizes.
• --context-size (default 512, also spelled --seq-len or --max-length) — tokens per sequence. Long documents are split, short ones padded. If it's larger than the tokenizer's own limit, it's clamped down with a warning.
• --output (default auto) — which model output to embed. auto prefers sentence_embedding, then last_hidden_state, then token_embeddings, then the first output. You can also pass an index (--output 1) or an exact name.
• --pooling (default auto) — cls, mean, max, lasttoken (last works too), or none.
• --normalize (default auto) — true or false, whether to L2-normalize the embeddings. auto turns it on when the config has a Normalize module, off otherwise.
• --warmup-batches (default 2) — untimed batches run before measuring.

How long to run

• --tokens — stop after this many input tokens.
• --minutes — stop after this many minutes, warmup and tokenization aren't included.

Whichever limit hits first stops the run, and it's checked after every batch.

Data and misc

• --data (default data/fineweb-10mb.txt) — text file to benchmark on.
• --seed (default 23) — bleh.
• --no-shuffle — keep the file's line order instead.
• --no-pack — by default, all text is concatenated and sliced into full context-size blocks, so every batch is dense and the tok/s numbers are honest. --no-pack goes back to one document per sequence with truncate-and-pad, which keeps document boundaries intact at the cost of some padding.
• --offline — self-explanatory.
• --trust-remote-code — pass trust_remote_code=True when loading the tokenizer. Off by default; only enable it for tokenizers you trust.
• --output-format (default table) — table, json, or csv.
• --output-file — also write the report to this file.
• --no-progress — hide the progress bars. -q/--quiet does the same but also quiets per-batch chatter; the config block, results, and version line always print either way. -v/--verbose adds extra detail.

Results

• Mean latency (per doc) — average time per document/sequence: each timed batch's wall time divided by --batch-size, then averaged over batches (std, and p50/p95 in json, come from the same per-doc samples).
• Mean ingest — tokens/sec, averaged over batches from non-pad tokens (attention-mask sum) only.
• Batches / Tokens / Elapsed — totals for the timed loop (warmup and tokenization excluded).

With default packing, a "document" is one dense context-size chunk sliced from the concatenated corpus; with --no-pack it's one source line per sequence (truncate-and-pad).

Benchmark text

data/fineweb-10mb.txt is ~10 MB of data taken from HuggingFaceFW/fineweb, config sample-10BT (license: ODC-By). To regenerate it:

python scripts/fetch_fineweb.py

Provenance (source revision, sizes, hash) lives in data/fineweb-10mb.meta.json.