Add attention benchmarking tools (#26835)

Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>
Co-authored-by: Claude <noreply@anthropic.com>

benchmarks/attention_benchmarks/README.md

+# vLLM Attention Benchmarking Suite
+
+Fast, flexible benchmarking for vLLM attention and MLA backends with an extended batch specification grammar.
+
+## Quick Start
+
+```bash
+cd benchmarks/attention_benchmarks
+
+# Run a pre-configured benchmark
+python benchmark.py --config configs/mla_decode.yaml
+python benchmark.py --config configs/mla_mixed_batch.yaml
+python benchmark.py --config configs/speculative_decode.yaml
+python benchmark.py --config configs/standard_attention.yaml
+python benchmark.py --config configs/reorder_threshold.yaml
+
+# Or run custom benchmarks
+python benchmark.py \
+    --backends flash flashinfer \
+    --batch-specs "q2k" "8q1s1k" "2q2k_32q1s1k" \
+    --output-csv results.csv
+```
+
+## Simplified Batch Specification Grammar
+
+Express workloads concisely using query length and sequence length:
+
+```python
+"q2k"              # 2048-token prefill (q_len=2048, seq_len=2048)
+"q1s1k"            # Decode: 1 token with 1K sequence
+"8q1s1k"           # 8 decode requests
+"q4s1k"            # 4-token extend (e.g., spec decode)
+"2q2k_32q1s1k"     # Mixed: 2 prefills + 32 decodes
+"16q4s1k"          # 16 spec decode (4 tokens each)
+```
+
+### Grammar Rule
+
+```text
+Format: (<count>?) q<q_len>(k?) (s<seq_len>(k?))?
+
+- count:   Number of identical requests (optional, default=1)
+- q_len:   Query length (number of new tokens)
+- seq_len: Total sequence length (optional, defaults to q_len for prefill)
+- 'k':     Multiplies value by 1024
+
+Mixed batches: Use _ to combine (e.g., "2q2k_32q1s1k")
+```
+
+**Note**: Decode, prefill, and spec decode are just different query lengths - no special syntax needed!
+
+## Pre-configured Benchmarks
+
+The suite includes several pre-configured YAML benchmark configurations:
+
+### MLA Decode Benchmark
+
+Tests pure decode performance across MLA backends with varying batch sizes and sequence lengths.
+
+```bash
+python benchmark.py --config configs/mla_decode.yaml
+```
+
+### MLA Mixed Batch Benchmark
+
+Tests chunked prefill performance with mixed prefill + decode batches.
+
+```bash
+python benchmark.py --config configs/mla_mixed_batch.yaml
+```
+
+### Speculative Decoding Benchmark
+
+Tests speculative decode scenarios (K-token verification) and reorder_batch_threshold optimization.
+
+```bash
+python benchmark.py --config configs/speculative_decode.yaml
+```
+
+### Standard Attention Benchmark
+
+Tests standard attention backends (Flash/Triton/FlashInfer) with pure prefill, decode, and mixed batches.
+
+```bash
+python benchmark.py --config configs/standard_attention.yaml
+```
+
+### Reorder Threshold Study
+
+**Question:** At what query length does the prefill pipeline become faster than the decode pipeline?
+
+Tests query lengths from 1-1024 across 9 batch sizes to find the crossover point. Uses `decode_vs_prefill` mode to compare both pipelines for each query length.
+
+```bash
+python benchmark.py --config configs/reorder_threshold.yaml
+```
+
+---
+
+## Universal Benchmark
+
+The `benchmark.py` script handles **all** backends - both standard attention and MLA.
+
+### Standard Attention (Flash/Triton/FlashInfer)
+
+```bash
+python benchmark.py \
+    --backends flash triton flashinfer \
+    --batch-specs "q2k" "8q1s1k" "2q2k_32q1s1k" \
+    --num-layers 10 \
+    --repeats 5 \
+    --output-csv results.csv
+```
+
+### MLA Backends
+
+```bash
+# Compare all MLA backends
+python benchmark.py \
+    --backends cutlass_mla flashinfer_mla flashattn_mla flashmla \
+    --batch-specs "64q1s1k" "64q1s4k" \
+    --output-csv mla_results.csv
+```
+
+### Parameter Sweeps
+
+Use `--sweep-param` and `--sweep-values` to run parameter sweeps from the CLI:
+
+#### CUTLASS MLA num-splits Optimization
+
+**Question:** What is the optimal `num_kv_splits` for CUTLASS MLA?
+
+```bash
+python benchmark.py \
+    --backend cutlass_mla \
+    --batch-specs "64q1s1k" "64q1s4k" "64q1s16k" \
+    --sweep-param num_kv_splits \
+    --sweep-values 1 2 4 8 16 \
+    --output-json optimal_splits.json
+```
+
+#### Reorder Batch Threshold Optimization
+
+**Question:** What's the optimal `reorder_batch_threshold` for speculative decoding?
+
+```bash
+python benchmark.py \
+    --backend flashmla \
+    --batch-specs "q4s1k" "q8s2k" \
+    --sweep-param reorder_batch_threshold \
+    --sweep-values 1 4 16 64 256 512 \
+    --output-csv threshold_sweep.csv
+```
+
+### All Command-Line Options
+
+```text
+--config CONFIG                     # Path to YAML config file (overrides other args)
+--backends BACKEND [BACKEND ...]    # flash, triton, flashinfer, cutlass_mla,
+                                    # flashinfer_mla, flashattn_mla, flashmla
+--backend BACKEND                   # Single backend (alternative to --backends)
+--batch-specs SPEC [SPEC ...]       # Batch specifications using extended grammar
+
+# Model configuration
+--num-layers N                      # Number of layers
+--head-dim N                        # Head dimension
+--num-q-heads N                     # Query heads
+--num-kv-heads N                    # KV heads
+--block-size N                      # Block size
+
+# Benchmark settings
+--device DEVICE                     # Device (default: cuda:0)
+--repeats N                         # Repetitions
+--warmup-iters N                    # Warmup iterations
+--profile-memory                    # Profile memory usage
+
+# Parameter sweeps
+--sweep-param PARAM                 # Parameter name to sweep (e.g., num_kv_splits,
+                                    # reorder_batch_threshold)
+--sweep-values N [N ...]            # Values to sweep for the parameter
+
+# Output
+--output-csv FILE                   # Save to CSV
+--output-json FILE                  # Save to JSON
+```
+
+## Hardware Requirements
+
+| Backend | Hardware |
+|---------|----------|
+| Flash/Triton/FlashInfer | Any CUDA GPU |
+| CUTLASS MLA | Blackwell (SM100+) |
+| FlashAttn MLA | Hopper (SM90+) |
+| FlashMLA | Hopper (SM90+) |
+| FlashInfer-MLA | Any CUDA GPU |
+
+## Using MLA Runner Directly
+
+All MLA backends are available through `mla_runner.run_mla_benchmark()`:
+
+```python
+from mla_runner import run_mla_benchmark
+from common import BenchmarkConfig
+
+config = BenchmarkConfig(
+    backend="cutlass_mla",
+    batch_spec="64q1s4k",
+    num_layers=10,
+    head_dim=576,
+    num_q_heads=128,
+    num_kv_heads=1,
+    block_size=128,
+    device="cuda:0",
+    repeats=5,
+    warmup_iters=3,
+)
+
+# CUTLASS MLA with specific num_kv_splits
+result = run_mla_benchmark("cutlass_mla", config, num_kv_splits=4)
+print(f"Time: {result.mean_time:.6f}s")
+
+# FlashInfer-MLA
+result = run_mla_benchmark("flashinfer_mla", config)
+
+# FlashAttn MLA (Hopper SM90+)
+result = run_mla_benchmark("flashattn_mla", config, reorder_batch_threshold=64)
+
+# FlashMLA (Hopper SM90+)
+result = run_mla_benchmark("flashmla", config, reorder_batch_threshold=64)
+```
+
+## Python API
+
+```python
+from batch_spec import parse_batch_spec, format_batch_spec, get_batch_stats
+from common import BenchmarkConfig, BenchmarkResult, ResultsFormatter
+
+# Parse batch specs
+requests = parse_batch_spec("2q2k_q4s1k_32q1s1k")
+print(format_batch_spec(requests))
+# "2 prefill (2x2k), 1 extend (1xq4kv1k), 32 decode (32x1k)"
+
+# Get batch statistics
+stats = get_batch_stats(requests)
+print(f"Total tokens: {stats['total_tokens']}")
+print(f"Num decode: {stats['num_decode']}, Num prefill: {stats['num_prefill']}")
+
+# Format results
+formatter = ResultsFormatter()
+formatter.save_csv(results, "output.csv")
+formatter.save_json(results, "output.json")
+```
+
+## Tips
+
+**1. Warmup matters** - Use `--warmup-iters 10` for stable results
+
+**2. Multiple repeats** - Use `--repeats 20` for low variance
+
+**3. Save results** - Always use `--output-csv` or `--output-json`
+
+**4. Test incrementally** - Start with `--num-layers 1 --repeats 1`
+
+**5. Extended grammar** - Leverage spec decode, chunked prefill patterns
+
+**6. Parameter sweeps** - Use `--sweep-param` and `--sweep-values` to find optimal values

benchmarks/attention_benchmarks/__init__.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+"""vLLM Attention Benchmarking Suite."""
+
+from .batch_spec import (
+    BatchRequest,
+    format_batch_spec,
+    get_batch_stats,
+    parse_batch_spec,
+    reorder_for_flashinfer,
+    split_by_type,
+)
+from .common import (
+    BenchmarkConfig,
+    BenchmarkResult,
+    MockLayer,
+    MockModelConfig,
+    ResultsFormatter,
+    get_attention_scale,
+    is_mla_backend,
+    setup_mla_dims,
+)
+
+__all__ = [
+    # Batch specification
+    "BatchRequest",
+    "parse_batch_spec",
+    "format_batch_spec",
+    "reorder_for_flashinfer",
+    "split_by_type",
+    "get_batch_stats",
+    # Benchmarking infrastructure
+    "BenchmarkConfig",
+    "BenchmarkResult",
+    "ResultsFormatter",
+    # Mock objects
+    "MockLayer",
+    "MockModelConfig",
+    # Utilities
+    "setup_mla_dims",
+    "get_attention_scale",
+    "is_mla_backend",
+]

benchmarks/attention_benchmarks/batch_spec.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+"""
+Simplified batch specification grammar for attention benchmarks.
+
+Grammar (underscore-separated segments):
+  Format: (<count>?) q<q_len>(k?) (s<seq_len>(k?))?
+
+  - count: Number of identical requests (optional, default=1)
+  - q_len: Query length (number of new tokens)
+  - seq_len: Total sequence length (optional, defaults to q_len for prefill)
+  - 'k' suffix: Multiplies value by 1024
+
+Common patterns:
+  - Prefill:  q_len == seq_len  (e.g., "q2k" → 2048 new tokens, 2048 seq)
+  - Decode:   q_len == 1        (e.g., "q1s1k" → 1 token, 1024 seq length)
+  - Extend:   q_len < seq_len   (e.g., "q4s1k" → 4 tokens, 1024 seq length)
+
+Examples:
+  q2k              -> [(2048, 2048)]           # Prefill: 2048 tokens
+  q1s1k            -> [(1, 1024)]              # Decode: 1 token, 1K sequence
+  8q1s1k           -> [(1, 1024)] * 8          # 8 decode requests
+  q4s1k            -> [(4, 1024)]              # 4-token extend (spec decode)
+  2q1k_32q1s1k     -> [(1024, 1024)] * 2 + [(1, 1024)] * 32  # Mixed batch
+  16q4s1k          -> [(4, 1024)] * 16         # 16 spec decode requests
+"""
+
+from collections import Counter
+from dataclasses import dataclass
+
+import regex as re
+
+
+@dataclass
+class BatchRequest:
+    """Represents a single request in a batch."""
+
+    q_len: int  # Query length (number of new tokens)
+    kv_len: int  # Total KV cache length
+
+    @property
+    def is_decode(self) -> bool:
+        """True if this is a decode request (q_len == 1)."""
+        return self.q_len == 1
+
+    @property
+    def is_prefill(self) -> bool:
+        """True if this is a pure prefill (q_len == kv_len)."""
+        return self.q_len == self.kv_len
+
+    @property
+    def is_extend(self) -> bool:
+        """True if this is context extension (q_len > 1, kv_len > q_len)."""
+        return self.q_len > 1 and self.kv_len > self.q_len
+
+    @property
+    def context_len(self) -> int:
+        """Context length (KV cache - query)."""
+        return self.kv_len - self.q_len
+
+    def as_tuple(self) -> tuple[int, int]:
+        """Return as (q_len, kv_len) tuple for compatibility."""
+        return (self.q_len, self.kv_len)
+
+
+def _parse_size(size_str: str, k_suffix: str) -> int:
+    """Parse size string with optional 'k' suffix."""
+    size = int(size_str)
+    return size * 1024 if k_suffix == "k" else size
+
+
+def parse_batch_spec(spec: str) -> list[BatchRequest]:
+    """
+    Parse batch specification string into list of BatchRequest objects.
+
+    Grammar: (<count>?) q<q_len>(k?) (s<seq_len>(k?))?
+
+    Args:
+        spec: Batch specification string (see module docstring for grammar)
+
+    Returns:
+        List of BatchRequest objects
+
+    Raises:
+        ValueError: If spec format is invalid
+    """
+    requests = []
+
+    for seg in spec.split("_"):
+        # Unified pattern: (<count>?) q<q_len>(k?) (s<seq_len>(k?))?
+        m = re.match(r"^(?:(\d+))?q(\d+)(k?)(?:s(\d+)(k?))?$", seg)
+        if m:
+            cnt = int(m.group(1)) if m.group(1) else 1
+            q_len = _parse_size(m.group(2), m.group(3))
+            kv_len = _parse_size(m.group(4), m.group(5)) if m.group(4) else q_len
+            requests.extend([BatchRequest(q_len=q_len, kv_len=kv_len)] * cnt)
+            continue
+
+        raise ValueError(f"Invalid batch spec segment: '{seg}'")
+
+    return requests
+
+
+def format_batch_spec(requests: list[BatchRequest]) -> str:
+    """
+    Format list of BatchRequest into human-readable string.
+
+    Groups requests by type and provides counts and sizes.
+
+    Args:
+        requests: List of BatchRequest objects
+
+    Returns:
+        Formatted string describing the batch
+    """
+    kinds = {
+        "prefill": [],
+        "extend": [],
+        "decode": [],
+    }
+
+    for req in requests:
+        tup = (req.q_len, req.kv_len)
+        if req.is_prefill:
+            kinds["prefill"].append(tup)
+        elif req.is_extend:
+            kinds["extend"].append(tup)
+        elif req.is_decode:
+            kinds["decode"].append(tup)
+
+    parts = []
+    for kind in ["prefill", "extend", "decode"]:
+        lst = kinds[kind]
+        if not lst:
+            continue
+
+        cnt_total = len(lst)
+        ctr = Counter(lst)
+        inner = []
+
+        for (q, kv), cnt in ctr.items():
+            if kind == "prefill":
+                size = f"{q // 1024}k" if q % 1024 == 0 else str(q)
+                inner.append(f"{cnt}x{size}")
+            elif kind == "decode":
+                size = f"{kv // 1024}k" if kv % 1024 == 0 else str(kv)
+                inner.append(f"{cnt}x{size}")
+            else:  # extend
+                qstr = f"{q // 1024}k" if q % 1024 == 0 else str(q)
+                kstr = f"{kv // 1024}k" if kv % 1024 == 0 else str(kv)
+                inner.append(f"{cnt}xq{qstr}kv{kstr}")
+
+        parts.append(f"{cnt_total} {kind} ({', '.join(inner)})")
+
+    return ", ".join(parts)
+
+
+def reorder_for_flashinfer(requests: list[BatchRequest]) -> list[BatchRequest]:
+    """
+    Reorder requests for FlashInfer: decode first, then prefill.
+
+    FlashInfer expects decode requests before prefill requests for
+    optimal performance.
+
+    Args:
+        requests: Original list of BatchRequest
+
+    Returns:
+        Reordered list with decode requests first
+    """
+    decodes = [r for r in requests if r.is_decode]
+    non_decodes = [r for r in requests if not r.is_decode]
+    return decodes + non_decodes
+
+
+def split_by_type(
+    requests: list[BatchRequest],
+) -> dict[str, list[BatchRequest]]:
+    """
+    Split requests by type for analysis.
+
+    Args:
+        requests: List of BatchRequest
+
+    Returns:
+        Dict with keys: 'decode', 'prefill', 'extend'
+    """
+    result = {
+        "decode": [],
+        "prefill": [],
+        "extend": [],
+    }
+
+    for req in requests:
+        if req.is_decode:
+            result["decode"].append(req)
+        elif req.is_prefill:
+            result["prefill"].append(req)
+        elif req.is_extend:
+            result["extend"].append(req)
+
+    return result
+
+
+def get_batch_stats(requests: list[BatchRequest]) -> dict:
+    """
+    Compute statistics about a batch.
+
+    Args:
+        requests: List of BatchRequest
+
+    Returns:
+        Dict with batch statistics
+    """
+    by_type = split_by_type(requests)
+
+    return {
+        "total_requests": len(requests),
+        "num_decode": len(by_type["decode"]),
+        "num_prefill": len(by_type["prefill"]),
+        "num_extend": len(by_type["extend"]),
+        "total_tokens": sum(r.q_len for r in requests),
+        "total_kv_cache": sum(r.kv_len for r in requests),
+        "max_q_len": max((r.q_len for r in requests), default=0),
+        "max_kv_len": max((r.kv_len for r in requests), default=0),
+        "avg_q_len": sum(r.q_len for r in requests) / len(requests) if requests else 0,
+        "avg_kv_len": (
+            sum(r.kv_len for r in requests) / len(requests) if requests else 0
+        ),
+    }

benchmarks/attention_benchmarks/common.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+"""Common utilities for attention benchmarking."""
+
+import csv
+import json
+import math
+from dataclasses import asdict, dataclass
+from pathlib import Path
+from typing import Any
+
+import numpy as np
+import torch
+from rich.console import Console
+from rich.table import Table
+
+# Mock classes for vLLM attention infrastructure
+
+
+class MockHfConfig:
+    """Mock HuggingFace config that satisfies vLLM's requirements."""
+
+    def __init__(self, mla_dims: dict):
+        self.num_attention_heads = mla_dims["num_q_heads"]
+        self.num_key_value_heads = mla_dims["num_kv_heads"]
+        self.hidden_size = mla_dims["head_dim"] * mla_dims["num_q_heads"]
+        self.model_type = "deepseek_v2"
+        self.is_encoder_decoder = False
+        self.kv_lora_rank = mla_dims["kv_lora_rank"]
+        self.qk_nope_head_dim = mla_dims["qk_nope_head_dim"]
+        self.qk_rope_head_dim = mla_dims["qk_rope_head_dim"]
+        self.v_head_dim = mla_dims["v_head_dim"]
+        self.qk_head_dim = mla_dims["qk_nope_head_dim"] + mla_dims["qk_rope_head_dim"]
+
+    def get_text_config(self):
+        return self
+
+
+# Import AttentionLayerBase at module level to avoid circular dependencies
+try:
+    from vllm.model_executor.layers.attention_layer_base import AttentionLayerBase
+
+    _HAS_ATTENTION_LAYER_BASE = True
+except ImportError:
+    _HAS_ATTENTION_LAYER_BASE = False
+    AttentionLayerBase = object  # Fallback
+
+
+class MockKVBProj:
+    """Mock KV projection layer for MLA prefill mode.
+
+    Mimics ColumnParallelLinear behavior for kv_b_proj in MLA backends.
+    Projects kv_c_normed to [qk_nope_head_dim + v_head_dim] per head.
+    """
+
+    def __init__(self, num_heads: int, qk_nope_head_dim: int, v_head_dim: int):
+        self.num_heads = num_heads
+        self.qk_nope_head_dim = qk_nope_head_dim
+        self.v_head_dim = v_head_dim
+        self.out_dim = qk_nope_head_dim + v_head_dim
+
+    def __call__(self, x: torch.Tensor) -> tuple[torch.Tensor]:
+        """
+        Project kv_c_normed to output space.
+
+        Args:
+            x: Input tensor [num_tokens, kv_lora_rank]
+
+        Returns:
+            Tuple containing output tensor
+                [num_tokens, num_heads, qk_nope_head_dim + v_head_dim]
+        """
+        num_tokens = x.shape[0]
+        result = torch.randn(
+            num_tokens,
+            self.num_heads,
+            self.out_dim,
+            device=x.device,
+            dtype=x.dtype,
+        )
+        return (result,)  # Return as tuple to match ColumnParallelLinear API
+
+
+class MockLayer(AttentionLayerBase):
+    """Mock attention layer with scale parameters and impl.
+
+    Inherits from AttentionLayerBase so it passes isinstance checks
+    in get_layers_from_vllm_config when FlashInfer prefill is enabled.
+    """
+
+    def __init__(self, device: torch.device, impl=None, kv_cache_spec=None):
+        # Don't call super().__init__() as AttentionLayerBase doesn't have __init__
+        self._k_scale = torch.tensor(1.0, device=device)
+        self._v_scale = torch.tensor(1.0, device=device)
+        self._q_scale = torch.tensor(1.0, device=device)
+        # Scalar floats for kernels that need them
+        self._k_scale_float = float(self._k_scale.item())
+        self._v_scale_float = float(self._v_scale.item())
+        self._q_scale_float = float(self._q_scale.item())
+        # AttentionImpl for metadata builders to query
+        self.impl = impl
+        # KV cache spec for get_kv_cache_spec
+        self._kv_cache_spec = kv_cache_spec
+
+    def get_attn_backend(self):
+        """Get the attention backend class (required by AttentionLayerBase)."""
+        # Return None as this is just a mock layer for benchmarking
+        return None
+
+    def get_kv_cache_spec(self):
+        """Get the KV cache spec (required by AttentionLayerBase)."""
+        return self._kv_cache_spec
+
+
+class MockModelConfig:
+    """Mock model configuration."""
+
+    def __init__(
+        self,
+        num_q_heads: int,
+        num_kv_heads: int,
+        head_dim: int,
+        dtype: torch.dtype = torch.float16,
+        max_model_len: int = 32768,
+    ):
+        self._n_q = num_q_heads
+        self._n_kv = num_kv_heads
+        self._d = head_dim
+        self.dtype = dtype
+        self.max_model_len = max_model_len
+
+    def get_num_attention_heads(self, _=None) -> int:
+        return self._n_q
+
+    def get_num_kv_heads(self, _=None) -> int:
+        return self._n_kv
+
+    def get_head_size(self) -> int:
+        return self._d
+
+    def get_num_layers(self) -> int:
+        """Mock method for layer count queries."""
+        return 1
+
+    def get_sliding_window_for_layer(self, _layer_idx: int):
+        """Mock method for sliding window queries."""
+        return None
+
+    def get_logits_soft_cap_for_layer(self, _layer_idx: int):
+        """Mock method for logits soft cap queries."""
+        return None
+
+    def get_sm_scale_for_layer(self, _layer_idx: int) -> float:
+        """Mock method for SM scale queries."""
+        return 1.0 / (self.get_head_size() ** 0.5)
+
+
+class MockParallelConfig:
+    """Mock parallel configuration."""
+
+    pass
+
+
+class MockCompilationConfig:
+    """Mock compilation configuration."""
+
+    def __init__(self):
+        self.full_cuda_graph = False
+        self.static_forward_context = {}
+
+
+class MockVLLMConfig:
+    """Mock VLLM configuration."""
+
+    def __init__(self):
+        self.compilation_config = MockCompilationConfig()
+
+
+class MockRunner:
+    """Mock GPU runner for metadata builders."""
+
+    def __init__(
+        self,
+        seq_lens: np.ndarray,
+        query_start_locs: np.ndarray,
+        device: torch.device,
+        num_q_heads: int,
+        num_kv_heads: int,
+        head_dim: int,
+        dtype: torch.dtype,
+    ):
+        self.model_config = MockModelConfig(num_q_heads, num_kv_heads, head_dim, dtype)
+        self.parallel_config = MockParallelConfig()
+        self.vllm_config = MockVLLMConfig()
+        self.seq_lens_np = seq_lens
+        self.query_start_loc_np = query_start_locs
+        self.device = device
+        self.attention_chunk_size = None
+        self.num_query_heads = num_q_heads
+        self.num_kv_heads = num_kv_heads
+        self.dtype = dtype
+
+
+@dataclass
+class ParameterSweep:
+    """Configuration for sweeping a backend parameter."""
+
+    param_name: str  # Name of the backend parameter to sweep
+    values: list[Any]  # List of values to test
+    include_auto: bool = False  # Also test with param unset (auto mode)
+    label_format: str = "{backend}_{param_name}_{value}"  # Result label template
+
+    def get_label(self, backend: str, value: Any) -> str:
+        """Generate a label for a specific parameter value."""
+        return self.label_format.format(
+            backend=backend, param_name=self.param_name, value=value
+        )
+
+
+@dataclass
+class ModelParameterSweep:
+    """Configuration for sweeping a model configuration parameter."""
+
+    param_name: str  # Name of the model config parameter to sweep (e.g., "num_q_heads")
+    values: list[Any]  # List of values to test
+    label_format: str = "{backend}_{param_name}_{value}"  # Result label template
+
+    def get_label(self, backend: str, value: Any) -> str:
+        """Generate a label for a specific parameter value."""
+        return self.label_format.format(
+            backend=backend, param_name=self.param_name, value=value
+        )
+
+
+@dataclass
+class BenchmarkConfig:
+    """Configuration for a single benchmark run."""
+
+    backend: str
+    batch_spec: str
+    num_layers: int
+    head_dim: int
+    num_q_heads: int
+    num_kv_heads: int
+    block_size: int
+    device: str
+    dtype: torch.dtype = torch.float16
+    repeats: int = 1
+    warmup_iters: int = 3
+    profile_memory: bool = False
+    use_cuda_graphs: bool = False
+
+    # MLA-specific
+    kv_lora_rank: int | None = None
+    qk_nope_head_dim: int | None = None
+    qk_rope_head_dim: int | None = None
+    v_head_dim: int | None = None
+
+    # Backend-specific tuning
+    num_kv_splits: int | None = None  # CUTLASS MLA
+    reorder_batch_threshold: int | None = None  # FlashAttn MLA, FlashMLA
+
+
+@dataclass
+class BenchmarkResult:
+    """Results from a single benchmark run."""
+
+    config: BenchmarkConfig
+    mean_time: float  # seconds
+    std_time: float  # seconds
+    min_time: float  # seconds
+    max_time: float  # seconds
+    throughput_tokens_per_sec: float | None = None
+    memory_allocated_mb: float | None = None
+    memory_reserved_mb: float | None = None
+    error: str | None = None
+
+    @property
+    def success(self) -> bool:
+        """Whether benchmark completed successfully."""
+        return self.error is None
+
+    def to_dict(self) -> dict[str, Any]:
+        """Convert to dictionary for serialization."""
+        return {
+            "config": asdict(self.config),
+            "mean_time": self.mean_time,
+            "std_time": self.std_time,
+            "min_time": self.min_time,
+            "max_time": self.max_time,
+            "throughput_tokens_per_sec": self.throughput_tokens_per_sec,
+            "memory_allocated_mb": self.memory_allocated_mb,
+            "memory_reserved_mb": self.memory_reserved_mb,
+            "error": self.error,
+        }
+
+
+class ResultsFormatter:
+    """Format and display benchmark results."""
+
+    def __init__(self, console: Console | None = None):
+        self.console = console or Console()
+
+    def print_table(
+        self,
+        results: list[BenchmarkResult],
+        backends: list[str],
+        compare_to_fastest: bool = True,
+    ):
+        """
+        Print results as a rich table.
+
+        Args:
+            results: List of BenchmarkResult
+            backends: List of backend names being compared
+            compare_to_fastest: Show percentage comparison to fastest
+        """
+        # Group by batch spec
+        by_spec = {}
+        for r in results:
+            spec = r.config.batch_spec
+            if spec not in by_spec:
+                by_spec[spec] = {}
+            by_spec[spec][r.config.backend] = r
+
+        # Create shortened backend names for display
+        def shorten_backend_name(name: str) -> str:
+            """Shorten long backend names for table display."""
+            # Remove common prefixes
+            name = name.replace("flashattn_mla", "famla")
+            name = name.replace("flashinfer_mla", "fimla")
+            name = name.replace("flashmla", "fmla")
+            name = name.replace("cutlass_mla", "cmla")
+            name = name.replace("numsplits", "ns")
+            return name
+
+        table = Table(title="Attention Benchmark Results")
+        table.add_column("Batch\nSpec", no_wrap=True)
+
+        multi = len(backends) > 1
+        for backend in backends:
+            short_name = shorten_backend_name(backend)
+            # Time column
+            col_time = f"{short_name}\nTime (s)"
+            table.add_column(col_time, justify="right", no_wrap=False)
+            if multi and compare_to_fastest:
+                # Relative performance column
+                col_rel = f"{short_name}\nvs Best"
+                table.add_column(col_rel, justify="right", no_wrap=False)
+
+        # Add rows
+        for spec in sorted(by_spec.keys()):
+            spec_results = by_spec[spec]
+            times = {b: r.mean_time for b, r in spec_results.items() if r.success}
+            best_time = min(times.values()) if times else 0.0
+
+            row = [spec]
+            for backend in backends:
+                if backend in spec_results:
+                    r = spec_results[backend]
+                    if r.success:
+                        row.append(f"{r.mean_time:.6f}")
+                        if multi and compare_to_fastest:
+                            pct = (
+                                (r.mean_time / best_time * 100) if best_time > 0 else 0
+                            )
+                            pct_str = f"{pct:.1f}%"
+                            if r.mean_time == best_time:
+                                pct_str = f"[bold green]{pct_str}[/]"
+                            row.append(pct_str)
+                    else:
+                        row.append("[red]ERROR[/]")
+                        if multi and compare_to_fastest:
+                            row.append("-")
+                else:
+                    row.append("-")
+                    if multi and compare_to_fastest:
+                        row.append("-")
+
+            table.add_row(*row)
+
+        self.console.print(table)
+
+    def save_csv(self, results: list[BenchmarkResult], path: str):
+        """Save results to CSV file."""
+        if not results:
+            return
+
+        path_obj = Path(path)
+        path_obj.parent.mkdir(parents=True, exist_ok=True)
+
+        with open(path, "w", newline="") as f:
+            writer = csv.DictWriter(
+                f,
+                fieldnames=[
+                    "backend",
+                    "batch_spec",
+                    "num_layers",
+                    "mean_time",
+                    "std_time",
+                    "throughput",
+                    "memory_mb",
+                ],
+            )
+            writer.writeheader()
+            for r in results:
+                writer.writerow(
+                    {
+                        "backend": r.config.backend,
+                        "batch_spec": r.config.batch_spec,
+                        "num_layers": r.config.num_layers,
+                        "mean_time": r.mean_time,
+                        "std_time": r.std_time,
+                        "throughput": r.throughput_tokens_per_sec or 0,
+                        "memory_mb": r.memory_allocated_mb or 0,
+                    }
+                )
+
+        self.console.print(f"[green]Saved CSV results to {path}[/]")
+
+    def save_json(self, results: list[BenchmarkResult], path: str):
+        """Save results to JSON file."""
+        path_obj = Path(path)
+        path_obj.parent.mkdir(parents=True, exist_ok=True)
+
+        data = [r.to_dict() for r in results]
+        with open(path, "w") as f:
+            json.dump(data, f, indent=2, default=str)
+
+        self.console.print(f"[green]Saved JSON results to {path}[/]")
+
+
+def setup_mla_dims(model_name: str = "deepseek-v3") -> dict:
+    """
+    Get MLA dimensions for known models.
+
+    Args:
+        model_name: Model identifier
+
+    Returns:
+        Dict with MLA dimension configuration
+    """
+    configs = {
+        "deepseek-v2": {
+            "kv_lora_rank": 512,
+            "qk_nope_head_dim": 128,
+            "qk_rope_head_dim": 64,
+            "v_head_dim": 128,
+            "num_q_heads": 128,
+            "num_kv_heads": 1,
+            "head_dim": 576,
+        },
+        "deepseek-v3": {
+            "kv_lora_rank": 512,
+            "qk_nope_head_dim": 128,
+            "qk_rope_head_dim": 64,
+            "v_head_dim": 128,
+            "num_q_heads": 128,
+            "num_kv_heads": 1,
+            "head_dim": 576,
+        },
+        "deepseek-v2-lite": {
+            "kv_lora_rank": 512,
+            "qk_nope_head_dim": 128,
+            "qk_rope_head_dim": 64,
+            "v_head_dim": 128,
+            "num_q_heads": 16,
+            "num_kv_heads": 1,
+            "head_dim": 576,
+        },
+    }
+
+    if model_name not in configs:
+        raise ValueError(
+            f"Unknown model '{model_name}'. Known models: {list(configs.keys())}"
+        )
+
+    return configs[model_name]
+
+
+def get_attention_scale(head_dim: int) -> float:
+    """Compute attention scale factor (1/sqrt(d))."""
+    return 1.0 / math.sqrt(head_dim)
+
+
+def is_mla_backend(backend: str) -> bool:
+    """
+    Check if backend is an MLA backend using the backend's is_mla() property.
+
+    Args:
+        backend: Backend name (e.g., "CUTLASS_MLA", "FLASHINFER_MLA")
+
+    Returns:
+        True if the backend is an MLA backend, False otherwise
+    """
+    from vllm.v1.attention.backends.registry import AttentionBackendEnum
+
+    try:
+        backend_class = AttentionBackendEnum[backend.upper()].get_class()
+        return backend_class.is_mla()
+    except (KeyError, ValueError, ImportError):
+        return False

benchmarks/attention_benchmarks/configs/mla_decode.yaml

+# MLA decode-only benchmark configuration
+
+model:
+  name: "deepseek-v3"
+  num_layers: 60
+  num_q_heads: 128
+  num_kv_heads: 1  # MLA uses single latent KV
+  head_dim: 576
+  kv_lora_rank: 512
+  qk_nope_head_dim: 128
+  qk_rope_head_dim: 64
+  v_head_dim: 128
+  block_size: 128  # CUTLASS MLA and FlashAttn MLA use 128
+
+batch_specs:
+  # Small batches, varying sequence lengths
+  - "16q1s512"     # 16 requests, 512 KV cache
+  - "16q1s1k"      # 16 requests, 1k KV cache
+  - "16q1s2k"      # 16 requests, 2k KV cache
+  - "16q1s4k"      # 16 requests, 4k KV cache
+
+  # Medium batches
+  - "32q1s1k"      # 32 requests, 1k KV cache
+  - "32q1s2k"      # 32 requests, 2k KV cache
+  - "32q1s4k"      # 32 requests, 4k KV cache
+  - "32q1s8k"      # 32 requests, 8k KV cache
+
+  # Large batches
+  - "64q1s1k"      # 64 requests, 1k KV cache
+  - "64q1s2k"      # 64 requests, 2k KV cache
+  - "64q1s4k"      # 64 requests, 4k KV cache
+  - "64q1s8k"      # 64 requests, 8k KV cache
+
+  # Very large batches
+  - "128q1s1k"     # 128 requests, 1k KV cache
+  - "128q1s2k"     # 128 requests, 2k KV cache
+
+  # Long context
+  - "32q1s16k"     # 32 requests, 16k KV cache
+  - "32q1s32k"     # 32 requests, 32k KV cache
+
+backends:
+  - cutlass_mla
+  - flashinfer_mla
+  - flashattn_mla  # Hopper only
+  - flashmla        # Hopper only
+
+device: "cuda:0"
+repeats: 5
+warmup_iters: 3
+profile_memory: true
+
+# Backend-specific tuning
+cutlass_mla:
+  num_kv_splits: auto  # or specific value like 4, 8, 16
+
+flashattn_mla:
+  reorder_batch_threshold: 512
+
+flashmla:
+  reorder_batch_threshold: 1

benchmarks/attention_benchmarks/configs/mla_mixed_batch.yaml

+# MLA mixed batch benchmark (prefill + decode)
+# Tests chunked prefill performance
+
+model:
+  name: "deepseek-v3"
+  num_layers: 60
+  num_q_heads: 128
+  num_kv_heads: 1
+  head_dim: 576
+  kv_lora_rank: 512
+  qk_nope_head_dim: 128
+  qk_rope_head_dim: 64
+  v_head_dim: 128
+  block_size: 128
+
+batch_specs:
+  # Small prefill + decode
+  - "1q1k_8q1s1k"           # 1 prefill + 8 decode
+  - "2q2k_16q1s1k"          # 2 prefill + 16 decode
+  - "4q1k_32q1s2k"          # 4 prefill + 32 decode
+
+  # Medium prefill + decode
+  - "2q4k_32q1s2k"          # 2 medium prefill + 32 decode
+  - "4q4k_64q1s2k"          # 4 medium prefill + 64 decode
+  - "8q2k_64q1s4k"          # 8 prefill + 64 decode
+
+  # Large prefill + decode (chunked prefill stress test)
+  - "2q8k_32q1s1k"          # 2 large prefill + 32 decode
+  - "1q16k_16q1s2k"         # 1 very large prefill + 16 decode
+  - "2q16k_32q1s4k"         # 2 very large prefill + 32 decode
+
+  # Context extension + decode
+  - "2q1kkv2k_16q1s1k"       # 2 extend + 16 decode
+  - "4q2kkv4k_32q1s2k"       # 4 extend + 32 decode
+  - "2q1kkv8k_32q1s2k"       # 2 large extend + 32 decode
+
+  # Explicitly chunked prefill
+  - "q8k"           # 8k prefill with chunking hint
+  - "q16k"          # 16k prefill with chunking hint
+  - "2q8k_32q1s2k"    # 2 chunked prefill + 32 decode
+
+  # High decode ratio (realistic serving)
+  - "1q2k_63q1s1k"          # 1 prefill + 63 decode
+  - "2q2k_62q1s2k"          # 2 prefill + 62 decode
+  - "4q4k_60q1s4k"          # 4 prefill + 60 decode
+
+backends:
+  - cutlass_mla
+  - flashinfer_mla
+  - flashattn_mla   # Hopper only
+  - flashmla        # Hopper only
+
+device: "cuda:0"
+repeats: 5
+warmup_iters: 3
+profile_memory: true
+
+# Analyze chunked prefill workspace size impact
+chunked_prefill:
+  test_workspace_sizes: [4096, 8192, 16384, 32768, 65536]

benchmarks/attention_benchmarks/configs/reorder_threshold.yaml

+# Study 4: What is optimal reorder_batch_threshold for MLA backends supporting query length > 1?
+# Question: At what query length does prefill pipeline become faster than decode pipeline?
+# Methodology: For each query length, compare decode vs prefill performance to find crossover point
+# Applies to: FlashAttn MLA, FlashMLA
+
+description: "Decode vs Prefill pipeline crossover analysis"
+
+# Test FlashAttn MLA
+backend: flashattn_mla
+
+# Mode: decode_vs_prefill comparison (special sweep mode)
+# For each batch spec, we'll test both decode and prefill pipelines
+mode: "decode_vs_prefill"
+
+# Query lengths to test (from old benchmark_mla_threshold.py methodology)
+# Each query length will be tested with BOTH decode and prefill pipelines:
+#   - decode: threshold >= query_length (forces decode pipeline)
+#   - prefill: threshold < query_length (forces prefill pipeline)
+#
+# We use q<N>s1k format which creates q_len=N, seq_len=1024 requests
+# This tests different query lengths with fixed sequence length context
+#
+# Using batch_spec_ranges for automatic generation:
+batch_spec_ranges:
+  - template: "q{q_len}s1k"
+    q_len:
+      start: 1
+      stop: 16
+      step: 1
+      end_inclusive: false
+  - template: "q{q_len}s1k"
+    q_len:
+      start: 16
+      stop: 64
+      step: 2
+      end_inclusive: false
+  - template: "q{q_len}s1k"
+    q_len:
+      start: 64
+      stop: 1024
+      step: 4
+      end_inclusive: true
+
+# Batch sizes to test (from old script)
+batch_sizes:
+  - 1
+  - 2
+  - 4
+  - 8
+  - 16
+  - 32
+  - 64
+  - 128
+  - 256
+
+# Model configuration (DeepSeek V2/V3 defaults)
+model:
+  num_layers: 10
+  head_dim: 576
+  num_q_heads: 128
+  num_kv_heads: 1
+  block_size: 128
+
+# Benchmark settings
+benchmark:
+  device: "cuda:0"
+  repeats: 15          # More repeats for spec decode variance
+  warmup_iters: 5
+  profile_memory: false
+
+# Output
+output:
+  csv: "reorder_threshold_results.csv"
+  json: "reorder_threshold_results.json"
+
+# Expected outcome (reproduces old benchmark_mla_threshold.py study):
+# - For each batch size, find the crossover point where prefill becomes faster than decode
+# - Show decode vs prefill performance across all query lengths
+# - Determine optimal reorder_batch_threshold based on last query length where decode is faster
+# - Understand how crossover point varies with batch size
+# - Provide data-driven guidance for default threshold value
+#
+# Methodology (from old script):
+# - Each query length tested with BOTH pipelines:
+#     * decode: threshold >= query_length (forces decode pipeline)
+#     * prefill: threshold < query_length (forces prefill pipeline)
+# - Compare which is faster to find crossover point
+#

benchmarks/attention_benchmarks/configs/speculative_decode.yaml

+# Speculative decoding benchmark configuration
+# Tests reorder_batch_threshold optimization
+
+model:
+  name: "deepseek-v3"
+  num_layers: 60
+  num_q_heads: 128
+  num_kv_heads: 1
+  head_dim: 576
+  kv_lora_rank: 512
+  qk_nope_head_dim: 128
+  qk_rope_head_dim: 64
+  v_head_dim: 128
+
+batch_specs:
+  # Pure speculative decode (K-token verification)
+  - "q2s1k"      # 2-token spec, 1k KV
+  - "q4s1k"      # 4-token spec, 1k KV
+  - "q8s1k"      # 8-token spec, 1k KV
+  - "q16s1k"     # 16-token spec, 1k KV
+
+  # Speculative with different context lengths
+  - "q4s2k"      # 4-token spec, 2k KV
+  - "q4s4k"      # 4-token spec, 4k KV
+  - "q8s2k"      # 8-token spec, 2k KV
+  - "q8s4k"      # 8-token spec, 4k KV
+
+  # Mixed: speculative + regular decode
+  - "32q4s1k"                    # 32 spec requests
+  - "16q4s1k_16q1s1k"              # 16 spec + 16 regular
+  - "8q8s2k_24q1s2k"               # 8 spec (8-tok) + 24 regular
+
+  # Mixed: speculative + prefill + decode
+  - "2q1k_16q4s1k_16q1s1k"         # 2 prefill + 16 spec + 16 decode
+  - "4q2k_32q4s2k_32q1s2k"         # 4 prefill + 32 spec + 32 decode
+
+  # Large batches with speculation
+  - "64q4s1k"                    # 64 spec requests
+  - "32q8s2k"                    # 32 spec (8-token)
+  - "16q16s4k"                   # 16 spec (16-token)
+
+# Backends that support query length > 1
+backends:
+  - flashattn_mla    # reorder_batch_threshold = 512
+  - flashmla          # reorder_batch_threshold = 1 (tunable)
+
+# FlashInfer-MLA also supports uniform spec-as-decode but with different mechanism
+# - flashinfer_mla
+
+# Benchmark settings
+benchmark:
+  device: "cuda:0"
+  repeats: 10  # More repeats for statistical significance
+  warmup_iters: 5
+  profile_memory: false
+
+# Test these threshold values for optimization
+parameter_sweep:
+  param_name: "reorder_batch_threshold"
+  values: [1, 2, 4, 8, 16, 32, 64, 128, 256, 512]
+  include_auto: false
+  label_format: "{backend}_threshold_{value}"

benchmarks/attention_benchmarks/configs/standard_attention.yaml

+# Standard attention backend benchmark configuration
+
+model:
+  num_layers: 32
+  num_q_heads: 32
+  num_kv_heads: 8  # GQA with 4:1 ratio
+  head_dim: 128
+  block_size: 16
+
+batch_specs:
+  # Pure prefill
+  - "q512"      # Small prefill (512 tokens)
+  - "q2k"       # Medium prefill (2048 tokens)
+  - "q4k"       # Large prefill (4096 tokens)
+  - "q8k"       # Very large prefill (8192 tokens)
+
+  # Pure decode
+  - "8q1s1k"      # 8 requests, 1k KV cache each
+  - "16q1s2k"     # 16 requests, 2k KV cache each
+  - "32q1s1k"     # 32 requests, 1k KV cache each
+  - "64q1s4k"     # 64 requests, 4k KV cache each
+
+  # Mixed prefill/decode
+  - "2q2k_8q1s1k"      # 2 prefill + 8 decode
+  - "4q1k_16q1s2k"     # 4 prefill + 16 decode
+  - "2q4k_32q1s1k"     # 2 large prefill + 32 decode
+
+  # Context extension
+  - "q1ks2k"          # 1k query, 2k sequence (chunked prefill)
+  - "2q1ks4k"         # 2 requests: 1k query, 4k sequence
+
+backends:
+  - flash
+  - triton
+  - flashinfer
+
+device: "cuda:0"
+repeats: 5
+warmup_iters: 3
+profile_memory: false

benchmarks/attention_benchmarks/runner.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+"""
+Standard attention benchmark runner - shared utilities for non-MLA benchmarks.
+
+This module provides helpers for running standard attention backends
+(FlashAttention, Triton, FlashInfer) with real vLLM integration.
+"""
+
+import types
+
+import numpy as np
+import torch
+from batch_spec import parse_batch_spec, reorder_for_flashinfer
+from common import BenchmarkConfig, BenchmarkResult, MockLayer, get_attention_scale
+
+from vllm.config import (
+    CacheConfig,
+    CompilationConfig,
+    DeviceConfig,
+    LoadConfig,
+    ModelConfig,
+    ParallelConfig,
+    SchedulerConfig,
+    VllmConfig,
+)
+from vllm.v1.attention.backends.utils import CommonAttentionMetadata
+from vllm.v1.kv_cache_interface import FullAttentionSpec
+
+# ============================================================================
+# Backend Configuration
+# ============================================================================
+
+
+_BACKEND_CONFIG = {
+    "flash": {
+        "module": "vllm.v1.attention.backends.flash_attn",
+        "backend_class": "FlashAttentionBackend",
+        "dtype": torch.float16,
+        "cache_layout": "standard",
+        # ^ [2, num_blocks, block_size, num_kv_heads, head_dim]
+    },
+    "triton": {
+        "module": "vllm.v1.attention.backends.triton_attn",
+        "backend_class": "TritonAttentionBackend",
+        "dtype": torch.float32,
+        "cache_layout": "standard",
+    },
+    "flashinfer": {
+        "module": "vllm.v1.attention.backends.flashinfer",
+        "backend_class": "FlashInferBackend",
+        "dtype": torch.float16,
+        "cache_layout": "flashinfer",
+        # ^ [num_blocks, 2, block_size, num_kv_heads, head_dim]
+    },
+}
+
+
+def _get_backend_config(backend: str) -> dict:
+    if backend not in _BACKEND_CONFIG:
+        raise ValueError(
+            f"Unknown backend: {backend}. "
+            f"Available: {', '.join(_BACKEND_CONFIG.keys())}"
+        )
+    return _BACKEND_CONFIG[backend]
+
+
+# ============================================================================
+# Metadata Building Helpers
+# ============================================================================
+
+
+def _build_common_attn_metadata(
+    q_lens: list[int],
+    kv_lens: list[int],
+    block_size: int,
+    device: torch.device,
+) -> CommonAttentionMetadata:
+    """Build CommonAttentionMetadata from query/kv lengths."""
+    batch_size = len(q_lens)
+    total_tokens = sum(q_lens)
+
+    query_start_loc = torch.zeros(batch_size + 1, dtype=torch.int32, device=device)
+    query_start_loc[1:] = torch.tensor(q_lens, dtype=torch.int32, device=device).cumsum(
+        0
+    )
+    query_start_loc_cpu = query_start_loc.cpu()
+
+    seq_lens = torch.tensor(kv_lens, dtype=torch.int32, device=device)
+    seq_lens_cpu = seq_lens.cpu()
+    max_seq_len = int(seq_lens_cpu.max())
+
+    context_lens = [kv - q for kv, q in zip(kv_lens, q_lens)]
+    num_computed_tokens_cpu = torch.tensor(context_lens, dtype=torch.int32)
+
+    max_blocks = (max(kv_lens) + block_size - 1) // block_size
+    num_blocks = batch_size * max_blocks
+    block_table_tensor = torch.arange(
+        num_blocks, dtype=torch.int32, device=device
+    ).view(batch_size, max_blocks)
+    slot_mapping = torch.arange(total_tokens, dtype=torch.int64, device=device)
+
+    max_query_len = max(q_lens)
+
+    return CommonAttentionMetadata(
+        query_start_loc=query_start_loc,
+        query_start_loc_cpu=query_start_loc_cpu,
+        seq_lens=seq_lens,
+        seq_lens_cpu=seq_lens_cpu,
+        num_computed_tokens_cpu=num_computed_tokens_cpu,
+        num_reqs=batch_size,
+        num_actual_tokens=total_tokens,
+        max_query_len=max_query_len,
+        max_seq_len=max_seq_len,
+        block_table_tensor=block_table_tensor,
+        slot_mapping=slot_mapping,
+        causal=True,
+    )
+
+
+def _create_vllm_config(
+    config: BenchmarkConfig,
+    dtype: torch.dtype,
+    max_num_blocks: int,
+) -> VllmConfig:
+    """Create a VllmConfig for benchmarking with mock model methods."""
+    model_config = ModelConfig(
+        model="meta-llama/Meta-Llama-3-8B",
+        tokenizer="meta-llama/Meta-Llama-3-8B",
+        trust_remote_code=False,
+        dtype=dtype,
+        seed=0,
+        max_model_len=1024,
+    )
+
+    cache_config = CacheConfig(
+        block_size=config.block_size,
+        cache_dtype="auto",
+        swap_space=0,
+    )
+    cache_config.num_gpu_blocks = max_num_blocks
+    cache_config.num_cpu_blocks = 0
+
+    parallel_config = ParallelConfig(tensor_parallel_size=1)
+    scheduler_config = SchedulerConfig(
+        max_num_seqs=256,
+        max_num_batched_tokens=8192,
+        max_model_len=8192,
+        is_encoder_decoder=False,
+        enable_chunked_prefill=True,
+    )
+    device_config = DeviceConfig()
+    load_config = LoadConfig()
+    compilation_config = CompilationConfig()
+
+    # Add mock methods for benchmark config values
+    model_config.get_num_layers = types.MethodType(
+        lambda self: config.num_layers, model_config
+    )
+    model_config.get_sliding_window_for_layer = types.MethodType(
+        lambda self, i: None, model_config
+    )
+    model_config.get_logits_soft_cap_for_layer = types.MethodType(
+        lambda self, i: 0.0, model_config
+    )
+    model_config.get_sm_scale_for_layer = types.MethodType(
+        lambda self, i: 1.0 / config.head_dim**0.5, model_config
+    )
+    model_config.get_num_attention_heads = types.MethodType(
+        lambda self, parallel_config=None: config.num_q_heads, model_config
+    )
+    model_config.get_num_kv_heads = types.MethodType(
+        lambda self, parallel_config=None: config.num_kv_heads, model_config
+    )
+    model_config.get_head_size = types.MethodType(
+        lambda self: config.head_dim, model_config
+    )
+    model_config.get_sliding_window = types.MethodType(lambda self: None, model_config)
+
+    return VllmConfig(
+        model_config=model_config,
+        cache_config=cache_config,
+        parallel_config=parallel_config,
+        scheduler_config=scheduler_config,
+        device_config=device_config,
+        load_config=load_config,
+        compilation_config=compilation_config,
+    )
+
+
+# ============================================================================
+# Backend Initialization
+# ============================================================================
+
+
+def _create_backend_impl(
+    backend_cfg: dict,
+    config: BenchmarkConfig,
+    device: torch.device,
+):
+    """Create backend implementation instance."""
+    import importlib
+
+    backend_module = importlib.import_module(backend_cfg["module"])
+    backend_class = getattr(backend_module, backend_cfg["backend_class"])
+
+    scale = get_attention_scale(config.head_dim)
+    dtype = backend_cfg["dtype"]
+
+    impl = backend_class.get_impl_cls()(
+        num_heads=config.num_q_heads,
+        head_size=config.head_dim,
+        scale=scale,
+        num_kv_heads=config.num_kv_heads,
+        alibi_slopes=None,
+        sliding_window=None,
+        kv_cache_dtype="auto",
+    )
+
+    kv_cache_spec = FullAttentionSpec(
+        block_size=config.block_size,
+        num_kv_heads=config.num_kv_heads,
+        head_size=config.head_dim,
+        dtype=dtype,
+    )
+
+    layer = MockLayer(device, kv_cache_spec=kv_cache_spec)
+
+    return backend_class, impl, layer, dtype
+
+
+def _create_metadata_builder(
+    backend_class,
+    kv_cache_spec: FullAttentionSpec,
+    vllm_config: VllmConfig,
+    device: torch.device,
+):
+    """Create metadata builder instance."""
+    return backend_class.get_builder_cls()(
+        kv_cache_spec=kv_cache_spec,
+        layer_names=["layer_0"],
+        vllm_config=vllm_config,
+        device=device,
+    )
+
+
+# ============================================================================
+# Tensor Creation Helpers
+# ============================================================================
+
+
+def _create_input_tensors(
+    config: BenchmarkConfig,
+    total_q: int,
+    device: torch.device,
+    dtype: torch.dtype,
+) -> tuple:
+    """Create Q, K, V input tensors for all layers."""
+    q_list = [
+        torch.randn(
+            total_q, config.num_q_heads, config.head_dim, device=device, dtype=dtype
+        )
+        for _ in range(config.num_layers)
+    ]
+    k_list = [
+        torch.randn(
+            total_q, config.num_kv_heads, config.head_dim, device=device, dtype=dtype
+        )
+        for _ in range(config.num_layers)
+    ]
+    v_list = [
+        torch.randn(
+            total_q, config.num_kv_heads, config.head_dim, device=device, dtype=dtype
+        )
+        for _ in range(config.num_layers)
+    ]
+    return q_list, k_list, v_list
+
+
+def _create_kv_cache(
+    config: BenchmarkConfig,
+    max_num_blocks: int,
+    cache_layout: str,
+    device: torch.device,
+    dtype: torch.dtype,
+) -> list:
+    """Create KV cache tensors for all layers."""
+    if cache_layout == "flashinfer":
+        # FlashInfer layout: [num_blocks, 2, block_size, num_kv_heads, head_dim]
+        cache_list = [
+            torch.zeros(
+                max_num_blocks,
+                2,
+                config.block_size,
+                config.num_kv_heads,
+                config.head_dim,
+                device=device,
+                dtype=dtype,
+            )
+            for _ in range(config.num_layers)
+        ]
+    else:
+        # Standard layout: [2, num_blocks, block_size, num_kv_heads, head_dim]
+        cache_list = [
+            torch.zeros(
+                2,
+                max_num_blocks,
+                config.block_size,
+                config.num_kv_heads,
+                config.head_dim,
+                device=device,
+                dtype=dtype,
+            )
+            for _ in range(config.num_layers)
+        ]
+    return cache_list
+
+
+# ============================================================================
+# Benchmark Execution
+# ============================================================================
+
+
+def _run_single_benchmark(
+    config: BenchmarkConfig,
+    impl,
+    layer,
+    q_list: list,
+    k_list: list,
+    v_list: list,
+    cache_list: list,
+    attn_metadata,
+    device: torch.device,
+    dtype: torch.dtype,
+) -> tuple:
+    """Run single benchmark iteration with warmup and timing loop."""
+    total_q = q_list[0].shape[0]
+    out = torch.empty(
+        total_q, config.num_q_heads, config.head_dim, device=device, dtype=dtype
+    )
+
+    # Warmup
+    for _ in range(config.warmup_iters):
+        for i in range(config.num_layers):
+            impl.forward(
+                layer,
+                q_list[i],
+                k_list[i],
+                v_list[i],
+                cache_list[i],
+                attn_metadata,
+                output=out,
+            )
+    torch.cuda.synchronize()
+
+    # Benchmark
+    times = []
+    for _ in range(config.repeats):
+        start = torch.cuda.Event(enable_timing=True)
+        end = torch.cuda.Event(enable_timing=True)
+
+        start.record()
+        for i in range(config.num_layers):
+            impl.forward(
+                layer,
+                q_list[i],
+                k_list[i],
+                v_list[i],
+                cache_list[i],
+                attn_metadata,
+                output=out,
+            )
+        end.record()
+
+        torch.cuda.synchronize()
+        elapsed_ms = start.elapsed_time(end)
+        times.append(elapsed_ms / 1000.0 / config.num_layers)  # seconds per layer
+
+    mem_stats = {}
+    if config.profile_memory:
+        mem_stats = {
+            "allocated_mb": torch.cuda.memory_allocated(device) / 1024**2,
+            "reserved_mb": torch.cuda.memory_reserved(device) / 1024**2,
+        }
+
+    return times, mem_stats
+
+
+# ============================================================================
+# Public API
+# ============================================================================
+
+
+def run_attention_benchmark(config: BenchmarkConfig) -> BenchmarkResult:
+    """
+    Run standard attention benchmark with real kernels.
+
+    Supports: flash, triton, flashinfer
+
+    Args:
+        config: Benchmark configuration
+
+    Returns:
+        BenchmarkResult with timing and memory statistics
+    """
+    device = torch.device(config.device)
+    torch.cuda.set_device(device)
+
+    backend_cfg = _get_backend_config(config.backend)
+
+    requests = parse_batch_spec(config.batch_spec)
+
+    if config.backend == "flashinfer":
+        requests = reorder_for_flashinfer(requests)
+
+    q_lens = [r.q_len for r in requests]
+    kv_lens = [r.kv_len for r in requests]
+    total_q = sum(q_lens)
+    max_kv = max(kv_lens)
+
+    max_num_blocks = (max_kv + config.block_size - 1) // config.block_size
+
+    backend_class, impl, layer, dtype = _create_backend_impl(
+        backend_cfg, config, device
+    )
+
+    common_metadata = _build_common_attn_metadata(
+        q_lens, kv_lens, config.block_size, device
+    )
+
+    kv_cache_spec = FullAttentionSpec(
+        block_size=config.block_size,
+        num_kv_heads=config.num_kv_heads,
+        head_size=config.head_dim,
+        dtype=dtype,
+    )
+
+    vllm_config = _create_vllm_config(config, dtype, max_num_blocks)
+
+    builder = _create_metadata_builder(
+        backend_class, kv_cache_spec, vllm_config, device
+    )
+
+    attn_metadata = builder.build(
+        common_prefix_len=0,
+        common_attn_metadata=common_metadata,
+    )
+
+    q_list, k_list, v_list = _create_input_tensors(config, total_q, device, dtype)
+
+    cache_list = _create_kv_cache(
+        config, max_num_blocks, backend_cfg["cache_layout"], device, dtype
+    )
+
+    times, mem_stats = _run_single_benchmark(
+        config,
+        impl,
+        layer,
+        q_list,
+        k_list,
+        v_list,
+        cache_list,
+        attn_metadata,
+        device,
+        dtype,
+    )
+
+    mean_time = np.mean(times)
+    throughput = total_q / mean_time if mean_time > 0 else 0
+
+    return BenchmarkResult(
+        config=config,
+        mean_time=mean_time,
+        std_time=np.std(times),
+        min_time=np.min(times),
+        max_time=np.max(times),
+        throughput_tokens_per_sec=throughput,
+        memory_allocated_mb=mem_stats.get("allocated_mb"),
+        memory_reserved_mb=mem_stats.get("reserved_mb"),
+    )