[Attention] Add FlashInfer Sparse MLA backend

benchmarks/attention_benchmarks/benchmark.py

@@ -43,6 +43,7 @@
     ModelParameterSweep,
     ParameterSweep,
     ResultsFormatter,
+    batch_spec_sort_key,
     is_mla_backend,
 )
 
@@ -218,10 +219,13 @@ def run_model_parameter_sweep(
                         by_param_and_spec[key].append(r)
                         break
 
-    # Sort by param value then spec
+    # Sort by param value then spec (batch_size, q_len, kv_len)
     sorted_keys = sorted(
         by_param_and_spec.keys(),
-        key=lambda x: (int(x[0]) if x[0].isdigit() else x[0], x[1]),
+        key=lambda x: (
+            int(x[0]) if x[0].isdigit() else x[0],
+            batch_spec_sort_key(x[1]),
+        ),
     )
 
     current_param_value = None
@@ -330,7 +334,7 @@ def run_parameter_sweep(
                 by_spec[spec] = []
             by_spec[spec].append(r)
 
-    for spec in sorted(by_spec.keys()):
+    for spec in sorted(by_spec.keys(), key=batch_spec_sort_key):
         results = by_spec[spec]
         best = min(results, key=lambda r: r.mean_time)
         console.print(
@@ -496,15 +500,18 @@ def main():
         if "description" in yaml_config:
             console.print(f"[dim]{yaml_config['description']}[/]")
 
-        # Override args with YAML values
-        # (YAML takes precedence unless CLI arg was explicitly set)
-        # Backend(s)
-        if "backend" in yaml_config:
-            args.backend = yaml_config["backend"]
-            args.backends = None
-        elif "backends" in yaml_config:
-            args.backends = yaml_config["backends"]
-            args.backend = None
+        # Override args with YAML values, but CLI args take precedence
+        # Check if CLI provided backends (they would be non-None and not default)
+        cli_backends_provided = args.backends is not None or args.backend is not None
+
+        # Backend(s) - only use YAML if CLI didn't specify
+        if not cli_backends_provided:
+            if "backend" in yaml_config:
+                args.backend = yaml_config["backend"]
+                args.backends = None
+            elif "backends" in yaml_config:
+                args.backends = yaml_config["backends"]
+                args.backend = None
 
         # Check for special modes
         if "mode" in yaml_config:
@@ -544,13 +551,15 @@ def main():
             args.num_kv_heads = model.get("num_kv_heads", args.num_kv_heads)
             args.block_size = model.get("block_size", args.block_size)
 
-        # Benchmark settings
-        if "benchmark" in yaml_config:
-            bench = yaml_config["benchmark"]
-            args.device = bench.get("device", args.device)
-            args.repeats = bench.get("repeats", args.repeats)
-            args.warmup_iters = bench.get("warmup_iters", args.warmup_iters)
-            args.profile_memory = bench.get("profile_memory", args.profile_memory)
+        # Benchmark settings (top-level keys)
+        if "device" in yaml_config:
+            args.device = yaml_config["device"]
+        if "repeats" in yaml_config:
+            args.repeats = yaml_config["repeats"]
+        if "warmup_iters" in yaml_config:
+            args.warmup_iters = yaml_config["warmup_iters"]
+        if "profile_memory" in yaml_config:
+            args.profile_memory = yaml_config["profile_memory"]
 
         # Parameter sweep configuration
         if "parameter_sweep" in yaml_config:

benchmarks/attention_benchmarks/common.py

@@ -16,13 +16,32 @@
 from rich.console import Console
 from rich.table import Table
 
+
+def batch_spec_sort_key(spec: str) -> tuple[int, int, int]:
+    """
+    Extract sorting key from batch spec: (batch_size, max_q_len, max_kv_len).
+
+    This ensures results are sorted by batch size first, then query length,
+    then sequence length, rather than alphabetically.
+    """
+    try:
+        requests = parse_batch_spec(spec)
+        batch_size = len(requests)
+        max_q_len = max(r.q_len for r in requests) if requests else 0
+        max_kv_len = max(r.kv_len for r in requests) if requests else 0
+        return (batch_size, max_q_len, max_kv_len)
+    except Exception:
+        # Fallback for unparseable specs
+        return (0, 0, 0)
+
+
 # Mock classes for vLLM attention infrastructure
 
 
 class MockHfConfig:
     """Mock HuggingFace config that satisfies vLLM's requirements."""
 
-    def __init__(self, mla_dims: dict):
+    def __init__(self, mla_dims: dict, index_topk: int | None = None):
         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"]
@@ -33,6 +52,8 @@ def __init__(self, mla_dims: dict):
         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"]
+        if index_topk is not None:
+            self.index_topk = index_topk
 
     def get_text_config(self):
         return self
@@ -83,6 +104,38 @@ def __call__(self, x: torch.Tensor) -> tuple[torch.Tensor]:
         return (result,)  # Return as tuple to match ColumnParallelLinear API
 
 
+class MockIndexer:
+    """Mock Indexer for sparse MLA backends.
+
+    Provides topk_indices_buffer that sparse MLA backends use to determine
+    which KV cache slots to attend to for each token.
+    """
+
+    def __init__(
+        self,
+        max_num_tokens: int,
+        topk_tokens: int,
+        device: torch.device,
+    ):
+        self.topk_tokens = topk_tokens
+        self.topk_indices_buffer = torch.zeros(
+            (max_num_tokens, topk_tokens),
+            dtype=torch.int32,
+            device=device,
+        )
+
+    def fill_random_indices(self, num_tokens: int, max_kv_len: int):
+        """Fill topk_indices_buffer with random valid indices for benchmarking."""
+        indices = torch.randint(
+            0,
+            max_kv_len,
+            (num_tokens, self.topk_tokens),
+            dtype=torch.int32,
+            device=self.topk_indices_buffer.device,
+        )
+        self.topk_indices_buffer[:num_tokens] = indices
+
+
 class MockLayer(AttentionLayerBase):
     """Mock attention layer with scale parameters and impl.
 
@@ -327,6 +380,9 @@ def print_table(
                 specs_order.append(spec)
             by_spec[spec][r.config.backend] = r
 
+        # Sort specs by (batch_size, q_len, kv_len) instead of alphabetically
+        specs_order = sorted(by_spec.keys(), key=batch_spec_sort_key)
+
         # Create shortened backend names for display
         def shorten_backend_name(name: str) -> str:
             """Shorten long backend names for table display."""
@@ -493,18 +549,20 @@ def get_attention_scale(head_dim: int) -> float:
 
 def is_mla_backend(backend: str) -> bool:
     """
-    Check if backend is an MLA backend using the backend's is_mla() property.
+    Check if backend is an MLA backend using the AttentionBackendEnum.
 
     Args:
-        backend: Backend name (e.g., "CUTLASS_MLA", "FLASHINFER_MLA")
+        backend: Backend name matching AttentionBackendEnum exactly
+        (e.g., "FLASHMLA_SPARSE")
 
     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()
+        backend_enum = AttentionBackendEnum[backend]
+        backend_class = backend_enum.get_class()
         return backend_class.is_mla()
-    except (KeyError, ValueError, ImportError):
+    except (KeyError, ValueError, ImportError, AttributeError):
         return False

benchmarks/attention_benchmarks/configs/mla_decode.yaml

@@ -3,7 +3,7 @@
 model:
   name: "deepseek-v3"
   num_layers: 60
-  num_q_heads: 128
+  num_q_heads: 128  # Base value, can be swept for TP simulation
   num_kv_heads: 1  # MLA uses single latent KV
   head_dim: 576
   kv_lora_rank: 512
@@ -12,6 +12,13 @@ model:
   v_head_dim: 128
   block_size: 128  # CUTLASS MLA and FlashAttn MLA use 128
 
+# Model parameter sweep: simulate tensor parallelism by varying num_q_heads
+# TP=1: 128 heads, TP=2: 64 heads, TP=4: 32 heads, TP=8: 16 heads
+model_parameter_sweep:
+  param_name: "num_q_heads"
+  values: [128, 64, 32, 16]
+  label_format: "{backend}_{value}h"
+
 batch_specs:
   # Small batches, varying sequence lengths
   - "16q1s512"     # 16 requests, 512 KV cache
@@ -34,28 +41,30 @@ batch_specs:
   # Very large batches
   - "128q1s1k"     # 128 requests, 1k KV cache
   - "128q1s2k"     # 128 requests, 2k KV cache
+  - "128q1s4k"     # 128 requests, 4k KV cache
+  - "128q1s8k"     # 128 requests, 8k 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
+  - CUTLASS_MLA
+  - FLASHINFER_MLA
+  - FLASH_ATTN_MLA  # Hopper only
+  - FLASHMLA        # Hopper only
 
 device: "cuda:0"
-repeats: 5
-warmup_iters: 3
+repeats: 100
+warmup_iters: 10
 profile_memory: true
 
 # Backend-specific tuning
-cutlass_mla:
+CUTLASS_MLA:
   num_kv_splits: auto  # or specific value like 4, 8, 16
 
-flashattn_mla:
+FLASH_ATTN_MLA:
   reorder_batch_threshold: 512
 
-flashmla:
+FLASHMLA:
   reorder_batch_threshold: 1

benchmarks/attention_benchmarks/configs/mla_mixed_batch.yaml

@@ -45,10 +45,10 @@ batch_specs:
   - "4q4k_60q1s4k"          # 4 prefill + 60 decode
 
 backends:
-  - cutlass_mla
-  - flashinfer_mla
-  - flashattn_mla   # Hopper only
-  - flashmla        # Hopper only
+  - CUTLASS_MLA
+  - FLASHINFER_MLA
+  - FLASH_ATTN_MLA   # Hopper only
+  - FLASHMLA         # Hopper only
 
 device: "cuda:0"
 repeats: 5

benchmarks/attention_benchmarks/configs/mla_prefill.yaml

@@ -0,0 +1,62 @@
+# MLA prefill-only benchmark configuration for sparse backends
+
+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
+
+# Model parameter sweep: simulate tensor parallelism by varying num_q_heads
+# TP=1: 128 heads, TP=2: 64 heads, TP=4: 32 heads, TP=8: 16 heads
+model_parameter_sweep:
+  param_name: "num_q_heads"
+  values: [128, 64, 32, 16]
+  label_format: "{backend}_{value}h"
+
+batch_specs:
+  # Pure prefill
+  - "1q512"
+  - "1q1k"
+  - "1q2k"
+  - "1q4k"
+  - "1q8k"
+
+  # Batched pure prefill
+  - "2q512"
+  - "2q1k"
+  - "2q2k"
+  - "2q4k"
+  - "2q8k"
+  - "4q512"
+  - "4q1k"
+  - "4q2k"
+  - "4q4k"
+  - "4q8k"
+  - "8q512"
+  - "8q1k"
+  - "8q2k"
+  - "8q4k"
+  - "8q8k"
+
+  # Extend
+  - "1q512s4k"
+  - "1q512s8k"
+  - "1q1ks8k"
+  - "1q2ks8k"
+  - "1q2ks16k"
+  - "1q4ks16k"
+
+backends:
+  - FLASHMLA_SPARSE
+  - FLASHINFER_MLA_SPARSE
+
+device: "cuda:0"
+repeats: 10
+warmup_iters: 3
+profile_memory: true

benchmarks/attention_benchmarks/configs/reorder_threshold.yaml

@@ -6,7 +6,7 @@
 description: "Decode vs Prefill pipeline crossover analysis"
 
 # Test FlashAttn MLA
-backend: flashattn_mla
+backend: FLASH_ATTN_MLA
 
 # Mode: decode_vs_prefill comparison (special sweep mode)
 # For each batch spec, we'll test both decode and prefill pipelines
@@ -62,11 +62,10 @@ model:
   block_size: 128
 
 # Benchmark settings
-benchmark:
-  device: "cuda:0"
-  repeats: 15          # More repeats for spec decode variance
-  warmup_iters: 5
-  profile_memory: false
+device: "cuda:0"
+repeats: 15          # More repeats for spec decode variance
+warmup_iters: 5
+profile_memory: false
 
 # Output
 output:

benchmarks/attention_benchmarks/configs/speculative_decode.yaml

@@ -41,18 +41,17 @@ batch_specs:
 
 # Backends that support query length > 1
 backends:
-  - flashattn_mla    # reorder_batch_threshold = 512
-  - flashmla          # reorder_batch_threshold = 1 (tunable)
+  - FLASH_ATTN_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
+# - FLASHINFER_MLA
 
 # Benchmark settings
-benchmark:
-  device: "cuda:0"
-  repeats: 10  # More repeats for statistical significance
-  warmup_iters: 5
-  profile_memory: false
+device: "cuda:0"
+repeats: 10  # More repeats for statistical significance
+warmup_iters: 5
+profile_memory: false
 
 # Test these threshold values for optimization
 parameter_sweep: