Sync from v0.13

benchmarks/benchmark_prefix_block_hash.py

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+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+"""
+Simple benchmark to compare prefix-cache block hashing algorithms.
+
+Example:
+    python benchmark_prefix_block_hash.py --num-blocks 20000 --block-size 32
+"""
+
+from __future__ import annotations
+
+import argparse
+import random
+import statistics
+import sys
+import time
+from collections.abc import Callable, Iterable, Sequence
+
+from vllm.utils.hashing import get_hash_fn_by_name
+from vllm.v1.core.kv_cache_utils import BlockHash, hash_block_tokens, init_none_hash
+
+SUPPORTED_ALGOS = ("sha256", "sha256_cbor", "xxhash", "xxhash_cbor")
+
+
+def _generate_blocks(
+    num_blocks: int, block_size: int, vocab_size: int, seed: int
+) -> list[list[int]]:
+    rng = random.Random(seed)
+    return [
+        [rng.randrange(vocab_size) for _ in range(block_size)]
+        for _ in range(num_blocks)
+    ]
+
+
+def _hash_all_blocks(
+    hash_fn: Callable[[object], bytes],
+    blocks: Iterable[Sequence[int]],
+) -> float:
+    parent_hash: BlockHash | None = None
+    start = time.perf_counter()
+    for block in blocks:
+        parent_hash = hash_block_tokens(hash_fn, parent_hash, block, extra_keys=None)
+    end = time.perf_counter()
+    return end - start
+
+
+def _benchmark(
+    hash_algo: str,
+    blocks: list[list[int]],
+    trials: int,
+) -> tuple[float, float, float] | None:
+    try:
+        hash_fn = get_hash_fn_by_name(hash_algo)
+        init_none_hash(hash_fn)
+        timings = [_hash_all_blocks(hash_fn, blocks) for _ in range(trials)]
+    except ModuleNotFoundError as exc:
+        print(f"Skipping {hash_algo}: {exc}", file=sys.stderr)
+        return None
+
+    avg = statistics.mean(timings)
+    best = min(timings)
+    # throughput: tokens / second
+    tokens_hashed = len(blocks) * len(blocks[0])
+    throughput = tokens_hashed / best
+    return avg, best, throughput
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--num-blocks", type=int, default=10000, help="Block count.")
+    parser.add_argument("--block-size", type=int, default=32, help="Tokens per block.")
+    parser.add_argument(
+        "--vocab-size", type=int, default=32000, help="Token id range [0, vocab_size)."
+    )
+    parser.add_argument("--seed", type=int, default=0, help="Random seed.")
+    parser.add_argument(
+        "--trials", type=int, default=5, help="Number of timed trials per algorithm."
+    )
+    parser.add_argument(
+        "--algorithms",
+        nargs="+",
+        default=SUPPORTED_ALGOS,
+        choices=SUPPORTED_ALGOS,
+        help="Hash algorithms to benchmark.",
+    )
+    args = parser.parse_args()
+
+    blocks = _generate_blocks(
+        args.num_blocks, args.block_size, args.vocab_size, args.seed
+    )
+    print(
+        f"Benchmarking {len(args.algorithms)} algorithms on "
+        f"{args.num_blocks} blocks (block size={args.block_size})."
+    )
+
+    for algo in args.algorithms:
+        result = _benchmark(algo, blocks, args.trials)
+        if result is None:
+            continue
+
+        avg, best, throughput = result
+        print(
+            f"{algo:14s} avg: {avg:.6f}s  best: {best:.6f}s  "
+            f"throughput: {throughput / 1e6:.2f}M tokens/s"
+        )
+
+
+if __name__ == "__main__":
+    main()