[ROCM][KERNEL] Paged attention for V1

csrc/rocm/attention.cu

@@ -272,6 +272,7 @@ __launch_bounds__(NUM_THREADS, 5) void paged_attention_ll4mi_QKV_mfma16_kernel(
     const float scale,    
     const int* __restrict__ block_tables,   // [num_seqs, max_num_blocks_per_seq]
     const int* __restrict__ context_lens,   // [num_seqs]
+    const int* __restrict__ query_start_loc_ptr,   // [num_seqs]
     const int max_num_blocks_per_seq,
     const float* __restrict__ alibi_slopes, // [num_heads]
     const int q_stride,
@@ -291,6 +292,13 @@ __launch_bounds__(NUM_THREADS, 5) void paged_attention_ll4mi_QKV_mfma16_kernel(
   const int rowid = laneid / 16;
 
   const auto seq_idx = blockIdx.x;
+  // NOTE queries with sequence len > 1 are prefills and taken care by another
+  // kernel.
+  if (query_start_loc_ptr != nullptr &&
+      (query_start_loc_ptr[seq_idx + 1] - query_start_loc_ptr[seq_idx]) != 1) {
+    return;
+  }
+
   const auto partition_idx = blockIdx.y;
 
   constexpr int T_PAR_SIZE = 256;  // token partition size set to 256
@@ -377,9 +385,10 @@ __launch_bounds__(NUM_THREADS, 5) void paged_attention_ll4mi_QKV_mfma16_kernel(
   // fetch Q in shared across warps and then write to registers
   const int local_qhead_idx = 4 * warpid + rowid;
   const int global_qhead_idx = wg_start_head_idx + local_qhead_idx;
-  const int64_t seq_idx64 = static_cast<int64_t>(seq_idx);
+  const int64_t query_start_off =
+      query_start_loc_ptr ? query_start_loc_ptr[seq_idx] : seq_idx;
   const scalar_t* q_ptr =
-      q + seq_idx64 * q_stride + global_qhead_idx * HEAD_SIZE;
+      q + query_start_off * q_stride + global_qhead_idx * HEAD_SIZE;
 
   const int qhead_element = lane16id * CONTIGUOUS_SCALAR_ELEMS_16B;
   if ((local_qhead_idx < GQA_RATIO) && (qhead_element < HEAD_SIZE)) {
@@ -777,6 +786,7 @@ __launch_bounds__(NUM_THREADS) void paged_attention_ll4mi_QKV_mfma4_kernel(
     const float scale,
     const int* __restrict__ block_tables,   // [num_seqs, max_num_blocks_per_seq]
     const int* __restrict__ context_lens,   // [num_seqs]
+    const int* __restrict__ query_start_loc_ptr,   // [num_seqs]
     const int max_num_blocks_per_seq,
     const float* __restrict__ alibi_slopes, // [num_heads]
     const int q_stride,
@@ -794,6 +804,12 @@ __launch_bounds__(NUM_THREADS) void paged_attention_ll4mi_QKV_mfma4_kernel(
   const int lane4id = laneid % 4;
 
   const auto seq_idx = blockIdx.x;
+  // NOTE queries with sequence len > 1 are prefills and taken care by another
+  // kernel.
+  if (query_start_loc_ptr != nullptr &&
+      (query_start_loc_ptr[seq_idx + 1] - query_start_loc_ptr[seq_idx] != 1)) {
+    return;
+  }
   const auto partition_idx = blockIdx.y;
   const auto partition_size = blockDim.x;
   const auto max_num_partitions = gridDim.y;
@@ -882,9 +898,11 @@ __launch_bounds__(NUM_THREADS) void paged_attention_ll4mi_QKV_mfma4_kernel(
     }
 
     // fetch q elements
-    // every 4 lanes fetch 8 elems, so warp fetches 8*16 = 128 elems
+    // every 4 lanes fetch 8 elems, so warp fetches 8*16 = 128 elemsc
+    const int64_t query_start_off =
+        query_start_loc_ptr ? query_start_loc_ptr[seq_idx] : seq_idx;
     const scalar_t* q_ptr =
-        q + seq_idx * q_stride + wg_start_head_idx * HEAD_SIZE;
+        q + query_start_off * q_stride + wg_start_head_idx * HEAD_SIZE;
     const _B16x8* q_ptrh8 = reinterpret_cast<const _B16x8*>(q_ptr);
     const int qhead_elemh8 = laneid / 4;
 
@@ -1267,10 +1285,19 @@ __launch_bounds__(NUM_THREADS) void paged_attention_ll4mi_reduce_kernel(
     const scalar_t* __restrict__ tmp_out,  // [num_seqs, num_heads,
                                            // max_num_partitions, head_size]
     const int* __restrict__ context_lens,  // [num_seqs]
+    const int* __restrict__ query_start_loc_ptr,  // [num_seqs]
     const int max_num_partitions) {
   const auto num_heads = gridDim.x;
   const auto head_idx = blockIdx.x;
   const auto seq_idx = blockIdx.y;
+
+  // NOTE queries with sequence len > 1 are prefills and taken care by another
+  // kernel.
+  if (query_start_loc_ptr != nullptr &&
+      (query_start_loc_ptr[seq_idx + 1] - query_start_loc_ptr[seq_idx] != 1)) {
+    return;
+  }
+
   const int context_len = context_lens[seq_idx];
   const int num_partitions = DIVIDE_ROUND_UP(context_len, PARTITION_SIZE);
   [[maybe_unused]] constexpr int NUM_WARPS = NUM_THREADS / WARP_SIZE;
@@ -1439,7 +1466,9 @@ __launch_bounds__(NUM_THREADS) void paged_attention_ll4mi_reduce_kernel(
       __fdividef(1.0f, shared_global_exp_sum + 1e-6f);
   acc *= inv_global_exp_sum;
 
-  OUTT* out_ptr = out + static_cast<int64_t>(seq_idx) * num_heads * HEAD_SIZE +
+  const int64_t query_start_off =
+      query_start_loc_ptr ? query_start_loc_ptr[seq_idx] : seq_idx;
+  OUTT* out_ptr = out + query_start_off * num_heads * HEAD_SIZE +
                   static_cast<int64_t>(head_idx) * HEAD_SIZE;
   if constexpr (std::is_same<OUTT, bit8_t>::value) {
     out_ptr[threadIdx.x] =
@@ -1466,6 +1495,7 @@ __launch_bounds__(NUM_THREADS) void paged_attention_ll4mi_QKV_mfma16_kernel(
     const float scale,
     const int* __restrict__ block_tables,    // [num_seqs, max_num_blocks_per_seq]
     const int* __restrict__ context_lens,    // [num_seqs]
+    const int* __restrict__ query_start_loc_ptr,  // [num_seqs]
     const int max_num_blocks_per_seq,
     const float* __restrict__ alibi_slopes,  // [num_heads]
     const int q_stride,
@@ -1492,6 +1522,7 @@ __launch_bounds__(NUM_THREADS) void paged_attention_ll4mi_QKV_mfma4_kernel(
     const float scale,
     const int* __restrict__ block_tables,    // [num_seqs, max_num_blocks_per_seq]
     const int* __restrict__ context_lens,    // [num_seqs]
+    const int* __restrict__ query_start_loc_ptr,  // [num_seqs]
     const int max_num_blocks_per_seq,
     const float* __restrict__ alibi_slopes,  // [num_heads]
     const int q_stride,
@@ -1515,41 +1546,42 @@ __launch_bounds__(NUM_THREADS) void paged_attention_ll4mi_reduce_kernel(
     const float* __restrict__ max_logits,  // [num_seqs, num_heads, max_num_partitions]
     const scalar_t* __restrict__ tmp_out,  // [num_seqs, num_heads, max_num_partitions, head_size]
     const int* __restrict__ context_lens,  // [num_seqs]
+    const int* __restrict__ query_start_loc_ptr,  // [num_seqs]
     const int max_num_partitions) {
   UNREACHABLE_CODE
 }
 // clang-format on
 
 #endif  // defined(__HIP__MI300_MI250__) TODO: Add NAVI support
 
-#define LAUNCH_CUSTOM_ATTENTION_MFMA16(GQA_RATIO)                             \
-  paged_attention_ll4mi_QKV_mfma16_kernel<T, KVT, KV_DTYPE, OUTT, BLOCK_SIZE, \
-                                          HEAD_SIZE, NTHR, ALIBI_ENABLED,     \
-                                          GQA_RATIO>                          \
-      <<<grid, block, 0, stream>>>(                                           \
-          query_ptr, key_cache_ptr, value_cache_ptr, num_kv_heads, scale,     \
-          block_tables_ptr, context_lens_ptr, max_num_blocks_per_seq,         \
-          alibi_slopes_ptr, q_stride, kv_block_stride, kv_head_stride,        \
-          exp_sums_ptr, max_logits_ptr, tmp_out_ptr, out_ptr, max_ctx_blocks, \
-          k_scale_ptr, v_scale_ptr);
-
-#define LAUNCH_CUSTOM_ATTENTION_MFMA4(GQA_RATIO)                              \
-  paged_attention_ll4mi_QKV_mfma4_kernel<T, KVT, KV_DTYPE, OUTT, BLOCK_SIZE,  \
-                                         HEAD_SIZE, NTHR, ALIBI_ENABLED,      \
-                                         GQA_RATIO>                           \
-      <<<grid, block, 0, stream>>>(                                           \
-          query_ptr, key_cache_ptr, value_cache_ptr, num_kv_heads, scale,     \
-          block_tables_ptr, context_lens_ptr, max_num_blocks_per_seq,         \
-          alibi_slopes_ptr, q_stride, kv_block_stride, kv_head_stride,        \
-          exp_sums_ptr, max_logits_ptr, tmp_out_ptr, out_ptr, max_ctx_blocks, \
-          k_scale_ptr, v_scale_ptr);
+#define LAUNCH_CUSTOM_ATTENTION_MFMA16(GQA_RATIO)                              \
+  paged_attention_ll4mi_QKV_mfma16_kernel<T, KVT, KV_DTYPE, OUTT, BLOCK_SIZE,  \
+                                          HEAD_SIZE, NTHR, ALIBI_ENABLED,      \
+                                          GQA_RATIO>                           \
+      <<<grid, block, 0, stream>>>(                                            \
+          query_ptr, key_cache_ptr, value_cache_ptr, num_kv_heads, scale,      \
+          block_tables_ptr, context_lens_ptr, query_start_loc_ptr,             \
+          max_num_blocks_per_seq, alibi_slopes_ptr, q_stride, kv_block_stride, \
+          kv_head_stride, exp_sums_ptr, max_logits_ptr, tmp_out_ptr, out_ptr,  \
+          max_ctx_blocks, k_scale_ptr, v_scale_ptr);
+
+#define LAUNCH_CUSTOM_ATTENTION_MFMA4(GQA_RATIO)                               \
+  paged_attention_ll4mi_QKV_mfma4_kernel<T, KVT, KV_DTYPE, OUTT, BLOCK_SIZE,   \
+                                         HEAD_SIZE, NTHR, ALIBI_ENABLED,       \
+                                         GQA_RATIO>                            \
+      <<<grid, block, 0, stream>>>(                                            \
+          query_ptr, key_cache_ptr, value_cache_ptr, num_kv_heads, scale,      \
+          block_tables_ptr, context_lens_ptr, query_start_loc_ptr,             \
+          max_num_blocks_per_seq, alibi_slopes_ptr, q_stride, kv_block_stride, \
+          kv_head_stride, exp_sums_ptr, max_logits_ptr, tmp_out_ptr, out_ptr,  \
+          max_ctx_blocks, k_scale_ptr, v_scale_ptr);
 
 #define LAUNCH_CUSTOM_REDUCTION(NPAR_LOOPS)                          \
   paged_attention_ll4mi_reduce_kernel<T, OUTT, HEAD_SIZE, HEAD_SIZE, \
                                       PARTITION_SIZE, NPAR_LOOPS>    \
       <<<reduce_grid, reduce_block, 0, stream>>>(                    \
           out_ptr, exp_sums_ptr, max_logits_ptr, tmp_out_ptr,        \
-          context_lens_ptr, max_num_partitions);
+          context_lens_ptr, query_start_loc_ptr, max_num_partitions);
 
 template <typename T, typename KVT, vllm::Fp8KVCacheDataType KV_DTYPE,
           int BLOCK_SIZE, int HEAD_SIZE, typename OUTT, int PARTITION_SIZE_OLD,
@@ -1559,16 +1591,24 @@ void paged_attention_custom_launcher(
     torch::Tensor& tmp_out, torch::Tensor& query, torch::Tensor& key_cache,
     torch::Tensor& value_cache, const int num_kv_heads, float scale,
     torch::Tensor& block_tables, torch::Tensor& context_lens,
-    int max_context_len, const std::optional<torch::Tensor>& alibi_slopes,
-    torch::Tensor& k_scale, torch::Tensor& v_scale) {
-  int num_seqs = query.size(0);
+    const std::optional<torch::Tensor>& query_start_loc, int max_context_len,
+    const std::optional<torch::Tensor>& alibi_slopes, torch::Tensor& k_scale,
+    torch::Tensor& v_scale) {
+  int num_seqs = block_tables.size(0);
   int num_heads = query.size(1);
   int head_size = query.size(2);
   int max_num_blocks_per_seq = block_tables.size(1);
   int q_stride = query.stride(0);
   int kv_block_stride = key_cache.stride(0);
   int kv_head_stride = key_cache.stride(1);
 
+  // NOTE: query start location is optional for V0 decode should not be used.
+  // If batch contains mix of prefills and decode, prefills should be skipped.
+  const int* query_start_loc_ptr =
+      query_start_loc
+          ? reinterpret_cast<const int*>(query_start_loc.value().data_ptr())
+          : nullptr;
+
   // NOTE: alibi_slopes is optional.
   const float* alibi_slopes_ptr =
       alibi_slopes
@@ -1700,8 +1740,8 @@ void paged_attention_custom_launcher(
   paged_attention_custom_launcher<T, KVT, KV_DTYPE, BLK_SIZE, HEAD_SIZE, T, \
                                   PSIZE, ALIBI_ENABLED>(                    \
       out, exp_sums, max_logits, tmp_out, query, key_cache, value_cache,    \
-      num_kv_heads, scale, block_tables, context_lens, max_context_len,     \
-      alibi_slopes, k_scale, v_scale);
+      num_kv_heads, scale, block_tables, context_lens, query_start_loc,     \
+      max_context_len, alibi_slopes, k_scale, v_scale);
 
 #define CALL_CUSTOM_LAUNCHER_ALIBI(T, KVT, KV_DTYPE, BLK_SIZE, HEAD_SIZE,      \
                                    PSIZE)                                      \
@@ -1750,6 +1790,7 @@ void paged_attention(
     double scale,
     torch::Tensor& block_tables, // [num_seqs, max_num_blocks_per_seq]
     torch::Tensor& context_lens, // [num_seqs]
+    const std::optional<torch::Tensor>& query_start_loc, // [num_seqs]
     int64_t block_size, int64_t max_context_len,
     const std::optional<torch::Tensor>& alibi_slopes,
     const std::string& kv_cache_dtype, torch::Tensor& k_scale,

csrc/rocm/ops.h

@@ -7,8 +7,9 @@ void paged_attention(torch::Tensor& out, torch::Tensor& exp_sums,
                      torch::Tensor& query, torch::Tensor& key_cache,
                      torch::Tensor& value_cache, int64_t num_kv_heads,
                      double scale, torch::Tensor& block_tables,
-                     torch::Tensor& context_lens, int64_t block_size,
-                     int64_t max_context_len,
+                     torch::Tensor& context_lens,
+                     const std::optional<torch::Tensor>& query_start_loc,
+                     int64_t block_size, int64_t max_context_len,
                      const std::optional<torch::Tensor>& alibi_slopes,
                      const std::string& kv_cache_dtype, torch::Tensor& k_scale,
                      torch::Tensor& v_scale);

csrc/rocm/torch_bindings.cpp

@@ -23,7 +23,9 @@ TORCH_LIBRARY_EXPAND(TORCH_EXTENSION_NAME, rocm_ops) {
       "                Tensor query, Tensor key_cache,"
       "                Tensor value_cache, int num_kv_heads,"
       "                float scale, Tensor block_tables,"
-      "                Tensor context_lens, int block_size,"
+      "                Tensor context_lens,"
+      "                Tensor? query_start_loc,"
+      "                int block_size,"
       "                int max_context_len,"
       "                Tensor? alibi_slopes,"
       "                str kv_cache_dtype,"

vllm/_custom_ops.py

@@ -110,6 +110,7 @@ def paged_attention_rocm(
     scale: float,
     block_tables: torch.Tensor,
     seq_lens: torch.Tensor,
+    query_start_loc: Optional[torch.Tensor],
     block_size: int,
     max_seq_len: int,
     alibi_slopes: Optional[torch.Tensor],
@@ -120,8 +121,9 @@ def paged_attention_rocm(
     torch.ops._rocm_C.paged_attention(out, exp_sum, max_logits, tmp_out, query,
                                       key_cache, value_cache, num_kv_heads,
                                       scale, block_tables, seq_lens,
-                                      block_size, max_seq_len, alibi_slopes,
-                                      kv_cache_dtype, k_scale, v_scale)
+                                      query_start_loc, block_size, max_seq_len,
+                                      alibi_slopes, kv_cache_dtype, k_scale,
+                                      v_scale)
 
 
 def mla_decode_kvcache_cpu(

vllm/attention/backends/rocm_flash_attn.py

@@ -14,19 +14,16 @@
 from vllm.attention.backends.utils import (CommonAttentionState,
                                            CommonMetadataBuilder)
 from vllm.attention.ops.paged_attn import (PagedAttention,
-                                           PagedAttentionMetadata)
+                                           PagedAttentionMetadata,
+                                           use_rocm_custom_paged_attention)
 from vllm.logger import init_logger
 from vllm.platforms import current_platform
 
 if TYPE_CHECKING:
     from vllm.worker.model_runner import ModelInputForGPUWithSamplingMetadata
 
 logger = init_logger(__name__)
-
 _PARTITION_SIZE_ROCM = 256
-_GPU_ARCH = torch.cuda.get_device_properties("cuda").gcnArchName
-_ON_NAVI = "gfx1" in _GPU_ARCH
-_ON_MI250_MI300 = any(arch in _GPU_ARCH for arch in ["gfx90a", "gfx942"])
 
 
 class ROCmFlashAttentionBackend(AttentionBackend):
@@ -790,7 +787,7 @@ def forward(
             num_seqs, num_heads, head_size = decode_query.shape
             block_size = value_cache.shape[3]
             gqa_ratio = num_heads // self.num_kv_heads
-            use_custom = _use_rocm_custom_paged_attention(
+            use_custom = use_rocm_custom_paged_attention(
                 decode_query.dtype, head_size, block_size, gqa_ratio,
                 decode_meta.max_decode_seq_len)
             if use_custom:
@@ -833,6 +830,7 @@ def forward(
                     decode_meta.seq_lens_tensor
                     if self.attn_type != AttentionType.ENCODER_DECODER else
                     decode_meta.encoder_seq_lens_tensor,
+                    None,
                     block_size,
                     max_seq_len,
                     self.alibi_slopes,
@@ -898,15 +896,3 @@ def _sdpa_attention(
             start = end
 
     return output
-
-
-def _use_rocm_custom_paged_attention(qtype: torch.dtype, head_size: int,
-                                     block_size: int, gqa_ratio: int,
-                                     max_seq_len: int) -> bool:
-    # rocm custom page attention not support on navi (gfx1*)
-    return (_ON_MI250_MI300 and not _ON_NAVI
-            and (qtype == torch.half or qtype == torch.bfloat16)
-            and (head_size == 64 or head_size == 128)
-            and (block_size == 16 or block_size == 32)
-            and (gqa_ratio >= 1 and gqa_ratio <= 16) and max_seq_len <= 32768
-            and envs.VLLM_ROCM_CUSTOM_PAGED_ATTN)