[VLM] Optimize get_rope_index for GLM4v (#17420)

Co-authored-by: luoyuan.luo <luoyuan.luo@antgroup.com>
This commit is contained in:
Yuan Luo
2026-02-01 18:59:15 +08:00
committed by GitHub
parent 0fe282543f
commit 4ea4f2a20c
2 changed files with 527 additions and 87 deletions

View File

@@ -0,0 +1,425 @@
# This script benchmarks MRotaryEmbedding.get_rope_index_glm4v (GLM4V mrope index builder).
# It generates synthetic multimodal input_ids + attention_mask (+ optional image/video grids),
# runs benchmarks.
#
# == Usage Examples ==
#
# python3 benchmark_rope_index.py --device cuda --num-tokens 1024 2048 --benchmark-iter 200
import argparse
import math
import time
from dataclasses import dataclass, field
from typing import Any
import numpy as np
import torch
from sglang.srt.layers.rotary_embedding import MRotaryEmbedding
# -----------------------------
# Minimal config objects
# -----------------------------
@dataclass
class DummyVisionConfig:
spatial_merge_size: int = 2
@dataclass
class DummyHFConfig:
image_token_id: int = 32000
video_start_token_id: int = 32001
video_end_token_id: int = 32002
vision_config: DummyVisionConfig = field(
default_factory=lambda: DummyVisionConfig(spatial_merge_size=2)
)
# -----------------------------
# Helpers
# -----------------------------
def calculate_stats(times: list[float]) -> dict[str, float]:
"""Calculate statistics from a list of times."""
times_array = np.array(times, dtype=np.float64)
return {
"mean": float(np.mean(times_array)),
"median": float(np.median(times_array)),
"p99": float(np.percentile(times_array, 99)),
"min": float(np.min(times_array)),
"max": float(np.max(times_array)),
}
def _sync(device: torch.device):
if device.type == "cuda":
torch.cuda.synchronize()
def _approx_hw(patches: int, merge: int) -> tuple[int, int]:
# want (h/merge)*(w/merge) ~= patches
gh = int(math.sqrt(max(1, patches)))
gw = max(1, patches // max(1, gh))
return gh * merge, gw * merge
def generate_test_data(
num_tokens: int,
batch_size: int,
hf_config: DummyHFConfig,
dtype: torch.dtype,
device: torch.device,
pad_ratio: float,
num_images_per_sample: int,
image_patch_tokens: int,
num_videos_per_sample: int,
video_patch_tokens: int,
seed: int,
):
"""
Generate synthetic (input_ids, attention_mask, image_grid_thw, video_grid_thw).
NOTE:
- image_grid_thw / video_grid_thw are global lists across the entire batch in encounter order,
matching the function's image_index/video_index behavior.
- image patches are represented by repeated image_token_id.
- video patches are represented by image_token_id wrapped with start/end tokens.
"""
torch.manual_seed(seed)
forbidden = {
0,
hf_config.image_token_id,
hf_config.video_start_token_id,
hf_config.video_end_token_id,
}
vocab_size = 50000
def rand_text(n: int) -> torch.Tensor:
# generate random ids not in forbidden
out = torch.randint(1, vocab_size, (n,), device=device, dtype=torch.long)
# fix forbidden by +1 until ok (cheap, deterministic enough for benchmark data)
for bad in forbidden:
out = torch.where(out == bad, out + 1, out)
return out
image_grids: list[list[int]] = []
video_grids: list[list[int]] = []
input_ids = torch.zeros((batch_size, num_tokens), device=device, dtype=torch.long)
attention_mask = torch.zeros(
(batch_size, num_tokens), device=device, dtype=torch.long
)
eff_len = int(round(num_tokens * (1.0 - pad_ratio)))
eff_len = max(1, min(num_tokens, eff_len))
min_needed = 1
min_needed += num_images_per_sample * image_patch_tokens
min_needed += num_videos_per_sample * (2 + video_patch_tokens)
if eff_len < min_needed:
num_images_per_sample = 0
num_videos_per_sample = 0
for b in range(batch_size):
blocks: list[torch.Tensor] = []
reserved = (
num_images_per_sample * image_patch_tokens
+ num_videos_per_sample * (2 + video_patch_tokens)
)
reserved = min(reserved, max(0, eff_len - 1))
text_budget = max(1, eff_len - reserved)
n_text_chunks = num_images_per_sample + num_videos_per_sample + 1
base = text_budget // n_text_chunks
rem = text_budget % n_text_chunks
text_chunks = [base + (1 if i < rem else 0) for i in range(n_text_chunks)]
tci = 0
for _ in range(num_images_per_sample):
blocks.append(rand_text(text_chunks[tci]))
tci += 1
blocks.append(
torch.full(
(image_patch_tokens,),
hf_config.image_token_id,
device=device,
dtype=torch.long,
)
)
h, w = _approx_hw(
image_patch_tokens, hf_config.vision_config.spatial_merge_size
)
image_grids.append([1, h, w])
for _ in range(num_videos_per_sample):
blocks.append(rand_text(text_chunks[tci]))
tci += 1
blocks.append(
torch.tensor(
[hf_config.video_start_token_id], device=device, dtype=torch.long
)
)
blocks.append(
torch.full(
(video_patch_tokens,),
hf_config.image_token_id,
device=device,
dtype=torch.long,
)
)
blocks.append(
torch.tensor(
[hf_config.video_end_token_id], device=device, dtype=torch.long
)
)
h, w = _approx_hw(
video_patch_tokens, hf_config.vision_config.spatial_merge_size
)
# first field = group count used by code; set to 1
video_grids.append([1, h, w])
blocks.append(rand_text(text_chunks[tci]))
tokens = torch.cat(blocks, dim=0)[:eff_len]
pad = torch.zeros(
(num_tokens - tokens.numel(),), device=device, dtype=torch.long
)
ids = torch.cat([tokens, pad], dim=0)
mask = torch.cat(
[
torch.ones((tokens.numel(),), device=device, dtype=torch.long),
torch.zeros(
(num_tokens - tokens.numel(),), device=device, dtype=torch.long
),
],
dim=0,
)
input_ids[b] = ids
attention_mask[b] = mask
image_grid_thw = (
torch.tensor(image_grids, device=device, dtype=torch.long)
if len(image_grids)
else None
)
video_grid_thw = (
torch.tensor(video_grids, device=device, dtype=torch.long)
if len(video_grids)
else None
)
return (
input_ids.to(dtype=torch.long),
attention_mask.to(dtype=torch.long),
image_grid_thw,
video_grid_thw,
)
def benchmark_rope_index(
model_name: str,
tp_size: int,
num_tokens: int,
batch_size: int,
pad_ratio: float,
spatial_merge_size: int,
num_images: int,
image_patch_tokens: int,
num_videos: int,
video_patch_tokens: int,
dtype: torch.dtype,
seed: int,
warmup_iter: int,
benchmark_iter: int,
device: torch.device,
):
torch.manual_seed(seed)
hf_config = DummyHFConfig(
image_token_id=32000,
video_start_token_id=32001,
video_end_token_id=32002,
vision_config=DummyVisionConfig(spatial_merge_size=spatial_merge_size),
)
print(80 * "=")
print(
f"Evaluating: {model_name} tp_size={tp_size} "
f"num_tokens={num_tokens} batch={batch_size} pad_ratio={pad_ratio} "
f"images/sample={num_images} image_patch_tokens={image_patch_tokens} "
f"videos/sample={num_videos} video_patch_tokens={video_patch_tokens} "
f"dtype={dtype} device={device}"
)
input_ids, attention_mask, image_grid_thw, video_grid_thw = generate_test_data(
num_tokens=num_tokens,
batch_size=batch_size,
hf_config=hf_config,
dtype=dtype,
device=device,
pad_ratio=pad_ratio,
num_images_per_sample=num_images,
image_patch_tokens=image_patch_tokens,
num_videos_per_sample=num_videos,
video_patch_tokens=video_patch_tokens,
seed=seed,
)
# Smoke test
has_mm = (image_grid_thw is not None) or (video_grid_thw is not None)
if has_mm:
pos, delta = MRotaryEmbedding.get_rope_index_glm4v(
input_ids=input_ids,
hf_config=hf_config,
image_grid_thw=image_grid_thw,
video_grid_thw=video_grid_thw,
attention_mask=attention_mask,
)
assert pos.shape == (3, batch_size, num_tokens)
assert delta.shape == (batch_size, 1)
# Warm up
for _ in range(warmup_iter):
if has_mm:
MRotaryEmbedding.get_rope_index_glm4v(
input_ids=input_ids,
hf_config=hf_config,
image_grid_thw=image_grid_thw,
video_grid_thw=video_grid_thw,
attention_mask=attention_mask,
)
MRotaryEmbedding.get_rope_index_glm4v(
input_ids=input_ids,
hf_config=hf_config,
image_grid_thw=None,
video_grid_thw=None,
attention_mask=attention_mask,
)
_sync(device)
# Time multimodal branch
multimodal_times = []
for _ in range(benchmark_iter):
_sync(device)
start = time.time()
MRotaryEmbedding.get_rope_index_glm4v(
input_ids=input_ids,
hf_config=hf_config,
image_grid_thw=image_grid_thw,
video_grid_thw=video_grid_thw,
attention_mask=attention_mask,
)
_sync(device)
multimodal_times.append(time.time() - start)
# Time fallback branch
fallback_times = []
for _ in range(benchmark_iter):
_sync(device)
start = time.time()
MRotaryEmbedding.get_rope_index_glm4v(
input_ids=input_ids,
hf_config=hf_config,
image_grid_thw=None,
video_grid_thw=None,
attention_mask=attention_mask,
)
_sync(device)
fallback_times.append(time.time() - start)
multimodal_stats = calculate_stats(multimodal_times)
fallback_stats = calculate_stats(fallback_times)
print(f"\nPerformance for config (B={batch_size}, T={num_tokens}):")
print(
f"Multimodal: mean={multimodal_stats['mean']:.8f}s, "
f"median={multimodal_stats['median']:.8f}s, "
f"p99={multimodal_stats['p99']:.8f}s"
)
print(
f"Fallback: mean={fallback_stats['mean']:.8f}s, "
f"median={fallback_stats['median']:.8f}s, "
f"p99={fallback_stats['p99']:.8f}s"
)
if has_mm:
speedup = (
multimodal_stats["mean"] / fallback_stats["mean"]
if fallback_stats["mean"] > 0
else float("inf")
)
print(f"Fallback Speedup over Multimodal: {speedup:.8f}x")
else:
speedup = float("nan")
print(
"[INFO] num_tokens too small for multimodal segments; skip multimodal benchmark."
)
print(f"Fallback Speedup over Multimodal: {speedup:.8f}x")
return multimodal_stats, fallback_stats, speedup
if __name__ == "__main__":
parser = argparse.ArgumentParser(
description="Benchmark GLM4V get_rope_index_glm4v."
)
parser.add_argument("--model-name", type=str, default="GLM4V")
parser.add_argument("--tp-size", type=int, default=1)
parser.add_argument(
"--device", type=str, default="cuda" if torch.cuda.is_available() else "cpu"
)
parser.add_argument("--warmup-iter", type=int, default=10)
parser.add_argument("--benchmark-iter", type=int, default=100)
parser.add_argument("--dtype", type=str, choices=["int64"], default="int64")
parser.add_argument("--seed", type=int, default=0)
# token length sweep
parser.add_argument("--num-tokens", type=int, nargs="+", required=False)
# data shape knobs
parser.add_argument("--batch-size", type=int, default=1)
parser.add_argument("--pad-ratio", type=float, default=0.0)
parser.add_argument("--spatial-merge-size", type=int, default=2)
parser.add_argument("--num-images", type=int, default=1)
parser.add_argument("--image-patch-tokens", type=int, default=256)
parser.add_argument("--num-videos", type=int, default=1)
parser.add_argument("--video-patch-tokens", type=int, default=256)
# output
parser.add_argument("--out-dir", type=str, default=".")
args = parser.parse_args()
print(args)
device = torch.device(args.device)
if args.num_tokens is None:
num_tokens_list = [2**i for i in range(0, 18)]
else:
num_tokens_list = args.num_tokens
rows: list[dict[str, Any]] = []
for num_tokens in num_tokens_list:
multimodal_stats, fallback_stats, speedup = benchmark_rope_index(
model_name=args.model_name,
tp_size=args.tp_size,
num_tokens=num_tokens,
batch_size=args.batch_size,
pad_ratio=args.pad_ratio,
spatial_merge_size=args.spatial_merge_size,
num_images=args.num_images,
image_patch_tokens=args.image_patch_tokens,
num_videos=args.num_videos,
video_patch_tokens=args.video_patch_tokens,
dtype=getattr(torch, args.dtype),
seed=args.seed,
warmup_iter=args.warmup_iter,
benchmark_iter=args.benchmark_iter,
device=device,
)

View File

@@ -1700,11 +1700,12 @@ class MRotaryEmbedding(RotaryEmbedding):
video_index += 1
remain_videos -= 1
ed = ed_video
llm_grid_t, llm_grid_h, llm_grid_w = (
t.item(),
h.item() // spatial_merge_size,
w.item() // spatial_merge_size,
)
# Avoid .item() lookups in repeated context
t_int, h_int, w_int = int(t), int(h), int(w)
llm_grid_t = t_int
llm_grid_h = h_int // spatial_merge_size
llm_grid_w = w_int // spatial_merge_size
text_len = ed - st
st_idx = (
@@ -1737,24 +1738,24 @@ class MRotaryEmbedding(RotaryEmbedding):
"qwen3_vl_moe",
):
t_index = (
torch.arange(llm_grid_t)
torch.arange(llm_grid_t, device=position_ids.device)
.view(-1, 1)
.expand(-1, llm_grid_h * llm_grid_w)
.flatten()
.expand(llm_grid_t, llm_grid_h * llm_grid_w)
.reshape(-1)
)
else:
raise RuntimeError(f"Unimplemented model type: {model_type}")
h_index = (
torch.arange(llm_grid_h)
torch.arange(llm_grid_h, device=position_ids.device)
.view(1, -1, 1)
.expand(llm_grid_t, -1, llm_grid_w)
.flatten()
.expand(llm_grid_t, llm_grid_h, llm_grid_w)
.reshape(-1)
)
w_index = (
torch.arange(llm_grid_w)
torch.arange(llm_grid_w, device=position_ids.device)
.view(1, 1, -1)
.expand(llm_grid_t, llm_grid_h, -1)
.flatten()
.expand(llm_grid_t, llm_grid_h, llm_grid_w)
.reshape(-1)
)
llm_pos_ids_list.append(
torch.stack([t_index, h_index, w_index]) + text_len + st_idx
@@ -1787,10 +1788,9 @@ class MRotaryEmbedding(RotaryEmbedding):
position_ids = (
position_ids.unsqueeze(0).expand(3, -1, -1).to(input_ids.device)
)
max_position_ids = position_ids.max(0, keepdim=False)[0].max(
-1, keepdim=True
)[0]
mrope_position_deltas = max_position_ids + 1 - s
max_position_ids = position_ids.amax(dim=0, keepdim=False)
mrope_position_deltas = max_position_ids.amax(-1, keepdim=True) + 1 - s
return position_ids, mrope_position_deltas
@staticmethod
@@ -2107,13 +2107,17 @@ class MRotaryEmbedding(RotaryEmbedding):
video_end_token_id = hf_config.video_end_token_id
spatial_merge_size = hf_config.vision_config.spatial_merge_size
# Preallocate lists for efficiency
mrope_position_deltas = []
if input_ids is not None and (
image_grid_thw is not None or video_grid_thw is not None
):
total_input_ids = input_ids
if attention_mask is None:
attention_mask = torch.ones_like(total_input_ids)
position_ids = torch.ones(
3,
input_ids.shape[0],
@@ -2121,28 +2125,36 @@ class MRotaryEmbedding(RotaryEmbedding):
dtype=input_ids.dtype,
device=input_ids.device,
)
image_index, video_index = 0, 0
video_group_index = 0
# Move attention mask to device once to avoid repeated transfers
attention_mask = attention_mask.to(total_input_ids.device)
for i, input_ids in enumerate(total_input_ids):
input_ids = input_ids[attention_mask[i] == 1]
input_tokens = input_ids.tolist()
input_token_type = []
for i, ids in enumerate(total_input_ids):
curr_mask = attention_mask[i]
ids_masked = ids[curr_mask == 1]
# Preallocate input_token_type for maximum speed
input_tokens = ids_masked.tolist()
input_token_type = [""] * len(input_tokens)
# Single pass through tokens for type assignment, using explicit indices for performance
video_check_flg = False
for token in input_tokens:
for j, token in enumerate(input_tokens):
if token == video_start_token_id:
video_check_flg = True
elif token == video_end_token_id:
video_check_flg = False
if token == image_token_id and not video_check_flg:
input_token_type.append("image")
input_token_type[j] = "image"
elif token == image_token_id and video_check_flg:
input_token_type.append("video")
input_token_type[j] = "video"
else:
input_token_type.append("text")
input_token_type[j] = "text"
# Use itertools.groupby for consecutive token type groups (unchanged logic)
input_type_group = []
for key, group in itertools.groupby(
enumerate(input_token_type), lambda x: x[1]
@@ -2154,12 +2166,13 @@ class MRotaryEmbedding(RotaryEmbedding):
llm_pos_ids_list = []
video_frame_num = 1
for modality_type, start_idx, end_idx in input_type_group:
st_idx = (
llm_pos_ids_list[-1].max() + 1
if len(llm_pos_ids_list) > 0
else 0
)
# st_idx can be computed by torch directly for speed
if llm_pos_ids_list:
st_idx = llm_pos_ids_list[-1].max().item() + 1
else:
st_idx = 0
if modality_type == "image":
t, h, w = (
@@ -2167,103 +2180,102 @@ class MRotaryEmbedding(RotaryEmbedding):
image_grid_thw[image_index][1],
image_grid_thw[image_index][2],
)
llm_grid_t, llm_grid_h, llm_grid_w = (
t.item(),
h.item() // spatial_merge_size,
w.item() // spatial_merge_size,
)
# Avoid .item() lookups in repeated context
t_int, h_int, w_int = int(t), int(h), int(w)
llm_grid_t = t_int
llm_grid_h = h_int // spatial_merge_size
llm_grid_w = w_int // spatial_merge_size
# Avoid unnecessary views/expands for speed, always flatten at the end
t_index = (
torch.arange(llm_grid_t)
torch.arange(llm_grid_t, device=position_ids.device)
.view(-1, 1)
.expand(-1, llm_grid_h * llm_grid_w)
.flatten()
.expand(llm_grid_t, llm_grid_h * llm_grid_w)
.reshape(-1)
)
h_index = (
torch.arange(llm_grid_h)
torch.arange(llm_grid_h, device=position_ids.device)
.view(1, -1, 1)
.expand(llm_grid_t, -1, llm_grid_w)
.flatten()
.expand(llm_grid_t, llm_grid_h, llm_grid_w)
.reshape(-1)
)
w_index = (
torch.arange(llm_grid_w)
torch.arange(llm_grid_w, device=position_ids.device)
.view(1, 1, -1)
.expand(llm_grid_t, llm_grid_h, -1)
.flatten()
.expand(llm_grid_t, llm_grid_h, llm_grid_w)
.reshape(-1)
)
llm_pos_ids_list.append(
torch.stack([t_index, h_index, w_index]) + st_idx
)
image_index += 1
video_frame_num = 1
elif modality_type == "video":
t, h, w = (
video_frame_num,
video_grid_thw[video_index][1],
video_grid_thw[video_index][2],
)
t = video_frame_num
h = video_grid_thw[video_index][1]
w = video_grid_thw[video_index][2]
llm_grid_t, llm_grid_h, llm_grid_w = (
t,
h.item() // spatial_merge_size,
w.item() // spatial_merge_size,
)
h_int, w_int = int(h), int(w)
llm_grid_h = h_int // spatial_merge_size
llm_grid_w = w_int // spatial_merge_size
for t_idx in range(llm_grid_t):
# Only one video frame at a time
for t_idx in range(t):
t_index = (
torch.tensor(t_idx)
torch.tensor(t_idx, device=position_ids.device)
.view(-1, 1)
.expand(-1, llm_grid_h * llm_grid_w)
.flatten()
.expand(1, llm_grid_h * llm_grid_w)
.reshape(-1)
)
h_index = (
torch.arange(llm_grid_h)
torch.arange(llm_grid_h, device=position_ids.device)
.view(1, -1, 1)
.expand(1, -1, llm_grid_w)
.flatten()
.expand(1, llm_grid_h, llm_grid_w)
.reshape(-1)
)
w_index = (
torch.arange(llm_grid_w)
torch.arange(llm_grid_w, device=position_ids.device)
.view(1, 1, -1)
.expand(1, llm_grid_h, -1)
.flatten()
.expand(1, llm_grid_h, llm_grid_w)
.reshape(-1)
)
llm_pos_ids_list.append(
torch.stack([t_index, h_index, w_index]) + st_idx
)
video_group_index += 1
if video_group_index >= video_grid_thw[video_index][0]:
video_index += 1
video_group_index = 0
video_frame_num += 1
else:
else: # text
text_len = end_idx - start_idx
llm_pos_ids_list.append(
torch.arange(text_len).view(1, -1).expand(3, -1) + st_idx
)
# Use in-place expand for improved performance
text_range = torch.arange(text_len, device=position_ids.device)
text_pos = text_range.view(1, -1).expand(3, text_len) + st_idx
llm_pos_ids_list.append(text_pos)
video_frame_num = 1
# Concatenate once outside for speed
llm_positions = torch.cat(llm_pos_ids_list, dim=1).reshape(3, -1)
position_ids[..., i, attention_mask[i] == 1] = llm_positions.to(
position_ids.device
)
# Use advanced indexing for assignment
idx_mask = curr_mask == 1
position_ids[..., i, idx_mask] = llm_positions.to(position_ids.device)
mrope_position_deltas.append(
llm_positions.max() + 1 - len(total_input_ids[i])
)
# Build tensor in one call at the end
mrope_position_deltas = torch.tensor(
mrope_position_deltas, device=input_ids.device
).unsqueeze(1)
return position_ids, mrope_position_deltas
else:
if attention_mask is not None:
# Use in-place operations whenever possible
position_ids = attention_mask.long().cumsum(-1) - 1
position_ids.masked_fill_(attention_mask == 0, 1)
position_ids = (
@@ -2271,22 +2283,25 @@ class MRotaryEmbedding(RotaryEmbedding):
.expand(3, -1, -1)
.to(attention_mask.device)
)
max_position_ids = position_ids.max(0, keepdim=False)[0].max(
-1, keepdim=True
)[0]
mrope_position_deltas = max_position_ids + 1 - attention_mask.shape[-1]
else:
position_ids = (
torch.arange(input_ids.shape[1], device=input_ids.device)
.view(1, 1, -1)
.expand(3, input_ids.shape[0], -1)
max_position_ids = position_ids.amax(dim=0, keepdim=False)
mrope_position_deltas = (
max_position_ids.amax(-1, keepdim=True)
+ 1
- attention_mask.shape[-1]
)
else:
length = input_ids.shape[1]
batch_size = input_ids.shape[0]
# Use torch.arange with in-place expansion
arange_ids = torch.arange(length, device=input_ids.device).view(
1, 1, -1
)
position_ids = arange_ids.expand(3, batch_size, length)
mrope_position_deltas = torch.zeros(
[input_ids.shape[0], 1],
[batch_size, 1],
device=input_ids.device,
dtype=input_ids.dtype,
)
return position_ids, mrope_position_deltas
@staticmethod