Remove tma padding for fwd inputs (#85)

csrc/sm100/collective/fmha_fusion.hpp

@@ -225,8 +225,8 @@ struct CausalMask : NoMask {
     if constexpr (IsQBegin) {
       return std::min(trip_count, int(ceil_div(size<0>(tile_shape), size<1>(tile_shape))));
     } else {
-      const int offset_tile_q = get<1>(problem_size) % get<1>(tile_shape);
-      return std::min(trip_count, int(ceil_div(get<0>(tile_shape) + offset_tile_q, get<1>(tile_shape))));
+      const int corner_count = int((get<1>(problem_size) % get<1>(tile_shape) || get<0>(problem_size) % get<0>(tile_shape))) ;
+      return std::min(trip_count, int(ceil_div(get<0>(tile_shape), get<1>(tile_shape))) + corner_count);
     }
   }
 

csrc/sm100/collective/sm100_fmha_load_tma_warpspecialized.hpp

@@ -95,32 +95,21 @@ struct Sm100FmhaLoadTmaWarpspecialized {
     auto dQ = args.dQ;
     auto dK = args.dK;
     auto dV = args.dV;
-    auto problem_shape_qk = problem_shape;
 
+    using IntProblemShape = cute::tuple<int, int, int, cute::tuple<cute::tuple<int, int>, int>>;
+
+    IntProblemShape problem_shape_qk;
     if constexpr (is_variable_length_v<tuple_element_t<0, ProblemShape>>) {
       auto cumulative_length_q = get<0>(problem_shape).cumulative_length;
-      if (cumulative_length_q != nullptr) {
-          int max_length_q = get<0>(problem_shape).max_length;
-          // for variable sequence lenght, the batch is in units of row_stride
-          get<2,1>(dQ) = get<0>(dQ);
-          get<3,1>(problem_shape_qk) = std::max(get<3,1>(problem_shape_qk), max_length_q * (1 + get<3,1>(problem_shape)));
-          // offset ptr by the amount we add back in later
-          ptr_Q -= max_length_q * get<0>(dQ);
-      }
-    }
-
-    if constexpr (is_variable_length_v<tuple_element_t<1, ProblemShape>>) {
-      auto cumulative_length_kv = get<1>(problem_shape).cumulative_length;
-      if (cumulative_length_kv != nullptr) {
-          int max_length_kv = get<1>(problem_shape).max_length;
-          // for variable sequence lenght, the batch is in units of row_stride
-          get<2,1>(dK) = get<0>(dK);
-          get<2,1>(dV) = get<0>(dV);
-          get<3,1>(problem_shape_qk) = std::max(get<3,1>(problem_shape_qk), max_length_kv * (1 + get<3,1>(problem_shape)));
-          // offset ptr by the amount we add back in later
-          ptr_K -= max_length_kv * get<0>(dK);
-          ptr_V -= max_length_kv * get<0>(dV);
+      auto cumulative_length_k = get<1>(problem_shape).cumulative_length;
+      if (cumulative_length_q != nullptr && cumulative_length_k != nullptr ) {
+          get<0>(problem_shape_qk) = get<0>(problem_shape).total_length;
+          get<1>(problem_shape_qk) = get<1>(problem_shape).total_length;
+          get<2>(problem_shape_qk) = get<2>(problem_shape);
+          get<3>(problem_shape_qk) = get<3>(problem_shape);
       }
+    } else {
+      problem_shape_qk = problem_shape;
     }
 
     auto params_qk = CollectiveMmaQK::to_underlying_arguments(
@@ -181,19 +170,16 @@ struct Sm100FmhaLoadTmaWarpspecialized {
     Tensor mQ_qdl_p = params.tma_load_q.get_tma_tensor(select<0,2,3>(problem_shape));
 
     int q_offs_0 = 0;
-    int q_offs_2_1 = 0;
 
     if constexpr (is_variable_length_v<tuple_element_t<0, ParamsProblemShape>>) {
       auto cumulative_length_q = get<0>(params_problem_shape).cumulative_length;
       if (cumulative_length_q != nullptr) {
-        int max_length_q = get<0>(params_problem_shape).max_length;
-        q_offs_0 = max_length_q - get<0>(problem_shape);
-        q_offs_2_1 = cumulative_length_q[get<2,1>(blk_coord_q)] + get<0>(problem_shape);
+        q_offs_0 = cumulative_length_q[get<2,1>(blk_coord_q)];
         get<2,1>(blk_coord_q) = 0;
       }
     }
 
-    Tensor mQ_qdl = domain_offset(make_coord(q_offs_0, _0{}, make_coord(_0{}, q_offs_2_1)), mQ_qdl_p);
+    Tensor mQ_qdl = domain_offset(make_coord(q_offs_0, _0{}, make_coord(_0{}, _0{})), mQ_qdl_p);
 
     Tensor gQ_qdl = local_tile(mQ_qdl, TileShapeQK{}, make_coord(_, _, _), Step<_1, X, _1>{});
     Tensor tSgQ_qdl = mma_qk.partition_A(gQ_qdl);
@@ -208,19 +194,16 @@ struct Sm100FmhaLoadTmaWarpspecialized {
     Tensor mK_kdl_p = params.tma_load_k.get_tma_tensor(select<1,2,3>(problem_shape));
 
     int kv_offs_0 = 0;
-    int kv_offs_2_1 = 0;
 
     if constexpr (is_variable_length_v<tuple_element_t<1, ParamsProblemShape>>) {
       auto cumulative_length = get<1>(params_problem_shape).cumulative_length;
       if (cumulative_length != nullptr) {
-        int max_length = get<1>(params_problem_shape).max_length;
-        kv_offs_0 = max_length - get<1>(problem_shape);
-        kv_offs_2_1 = cumulative_length[get<2,1>(blk_coord_kv)] + get<1>(problem_shape);
+        kv_offs_0 = cumulative_length[get<2,1>(blk_coord_kv)];
         get<2,1>(blk_coord_kv) = 0;
       }
     }
 
-    Tensor mK_kdl = domain_offset(make_coord(kv_offs_0, _0{}, make_coord(_0{}, kv_offs_2_1)), mK_kdl_p);
+    Tensor mK_kdl = domain_offset(make_coord(kv_offs_0, _0{}, make_coord(_0{}, _0{})), mK_kdl_p);
 
     Tensor gK_kdl = local_tile(mK_kdl, TileShapeQK{}, make_coord(_, _, _), Step<X, _1, _1>{});
     Tensor tSgK_kdl = mma_qk.partition_B(gK_kdl);
@@ -235,7 +218,7 @@ struct Sm100FmhaLoadTmaWarpspecialized {
     ThrMMA mma_pv = typename CollectiveMmaPV::TiledMma{}.get_slice(0);
     Tensor mV_dkl_p = params.tma_load_v.get_tma_tensor(select<2,1,3>(problem_shape));
 
-    Tensor mV_dkl = domain_offset(make_coord(_0{}, kv_offs_0, make_coord(_0{}, kv_offs_2_1)), mV_dkl_p);
+    Tensor mV_dkl = domain_offset(make_coord(_0{}, kv_offs_0, make_coord(_0{}, _0{})), mV_dkl_p);
 
     Tensor gV_dkl = local_tile(mV_dkl, TileShapePV{}, make_coord(_, _, _), Step<X, _1, _1>{});
     Tensor tOgV_dkl = mma_pv.partition_B(gV_dkl);

csrc/sm100/collective/sm100_fmha_mla_load_tma_warpspecialized.hpp

@@ -102,32 +102,21 @@ struct Sm100MlaFwdLoadTmaWarpspecialized {
     auto dQ = args.dQ;
     auto dK = args.dK;
     auto dV = args.dV;
-    auto problem_shape_qk = replace<2>(problem_shape, get<2, 0>(problem_shape) + get<2, 1>(problem_shape));
 
+    using IntProblemShape = cute::tuple<int, int, int, cute::tuple<cute::tuple<int, int>, int>>;
+
+    IntProblemShape problem_shape_qk;
     if constexpr (is_variable_length_v<tuple_element_t<0, ProblemShape>>) {
       auto cumulative_length_q = get<0>(problem_shape).cumulative_length;
-      if (cumulative_length_q != nullptr) {
-          int max_length_q = get<0>(problem_shape).max_length;
-          // for variable sequence lenght, the batch is in units of row_stride
-          get<2,1>(dQ) = get<0>(dQ);
-          get<3,1>(problem_shape_qk) = std::max(get<3,1>(problem_shape_qk), max_length_q * (1 + get<3,1>(problem_shape)));
-          // offset ptr by the amount we add back in later
-          ptr_Q -= max_length_q * get<0>(dQ);
-      }
-    }
-
-    if constexpr (is_variable_length_v<tuple_element_t<1, ProblemShape>>) {
-      auto cumulative_length_kv = get<1>(problem_shape).cumulative_length;
-      if (cumulative_length_kv != nullptr) {
-          int max_length_kv = get<1>(problem_shape).max_length;
-          // for variable sequence lenght, the batch is in units of row_stride
-          get<2,1>(dK) = get<0>(dK);
-          get<2,1>(dV) = get<0>(dV);
-          get<3,1>(problem_shape_qk) = std::max(get<3,1>(problem_shape_qk), max_length_kv * (1 + get<3,1>(problem_shape)));
-          // offset ptr by the amount we add back in later
-          ptr_K -= max_length_kv * get<0>(dK);
-          ptr_V -= max_length_kv * get<0>(dV);
+      auto cumulative_length_k = get<1>(problem_shape).cumulative_length;
+      if (cumulative_length_q != nullptr && cumulative_length_k != nullptr ) {
+          get<0>(problem_shape_qk) = get<0>(problem_shape).total_length;
+          get<1>(problem_shape_qk) = get<1>(problem_shape).total_length;
+          get<2>(problem_shape_qk) = get<2, 0>(problem_shape) + get<2, 1>(problem_shape);
+          get<3>(problem_shape_qk) = get<3>(problem_shape);
       }
+    } else {
+      problem_shape_qk = replace<2>(problem_shape, get<2, 0>(problem_shape) + get<2, 1>(problem_shape));;
     }
 
     auto problem_shape_pv = replace<1>(select<0,2,1,3>(problem_shape_qk), get<2, 0>(problem_shape));
@@ -192,19 +181,16 @@ struct Sm100MlaFwdLoadTmaWarpspecialized {
     Tensor mQ_qdl_p = params.tma_load_q.get_tma_tensor(select<0,2,3>(problem_shape_qk));
 
     int q_offs_0 = 0;
-    int q_offs_2_1 = 0;
 
     if constexpr (is_variable_length_v<tuple_element_t<0, ParamsProblemShape>>) {
       auto cumulative_length_q = get<0>(params_problem_shape).cumulative_length;
       if (cumulative_length_q != nullptr) {
-        int max_length_q = get<0>(params_problem_shape).max_length;
-        q_offs_0 = max_length_q - get<0>(problem_shape);
-        q_offs_2_1 = cumulative_length_q[get<2,1>(blk_coord_q)] + get<0>(problem_shape);
+        q_offs_0 = cumulative_length_q[get<2,1>(blk_coord_q)];
         get<2,1>(blk_coord_q) = 0;
       }
     }
 
-    Tensor mQ_qdl = domain_offset(make_coord(q_offs_0, _0{}, make_coord(_0{}, q_offs_2_1)), mQ_qdl_p);
+    Tensor mQ_qdl = domain_offset(make_coord(q_offs_0, _0{}, make_coord(_0{}, _0{})), mQ_qdl_p);
 
     Tensor gQ_qdl = local_tile(mQ_qdl, TileShapeQK{}, make_coord(_, _, _), Step<_1, X, _1>{});
     Tensor tSgQ_qdl = mma_qk.partition_A(gQ_qdl);
@@ -219,19 +205,16 @@ struct Sm100MlaFwdLoadTmaWarpspecialized {
     Tensor mK_kdl_p = params.tma_load_k.get_tma_tensor(select<1,2,3>(problem_shape_qk));
 
     int kv_offs_0 = 0;
-    int kv_offs_2_1 = 0;
 
     if constexpr (is_variable_length_v<tuple_element_t<1, ParamsProblemShape>>) {
       auto cumulative_length = get<1>(params_problem_shape).cumulative_length;
       if (cumulative_length != nullptr) {
-        int max_length = get<1>(params_problem_shape).max_length;
-        kv_offs_0 = max_length - get<1>(problem_shape);
-        kv_offs_2_1 = cumulative_length[get<2,1>(blk_coord_kv)] + get<1>(problem_shape);
+        kv_offs_0 = cumulative_length[get<2,1>(blk_coord_kv)];
         get<2,1>(blk_coord_kv) = 0;
       }
     }
 
-    Tensor mK_kdl = domain_offset(make_coord(kv_offs_0, _0{}, make_coord(_0{}, kv_offs_2_1)), mK_kdl_p);
+    Tensor mK_kdl = domain_offset(make_coord(kv_offs_0, _0{}, make_coord(_0{}, _0{})), mK_kdl_p);
 
     Tensor gK_kdl = local_tile(mK_kdl, TileShapeQK{}, make_coord(_, _, _), Step<X, _1, _1>{});
     Tensor tSgK_kdl = mma_qk.partition_B(gK_kdl);
@@ -246,7 +229,7 @@ struct Sm100MlaFwdLoadTmaWarpspecialized {
     ThrMMA mma_pv = typename CollectiveMmaPV::TiledMma{}.get_slice(0);
     Tensor mV_dkl_p = params.tma_load_v.get_tma_tensor(select<2,1,3>(problem_shape_v));
 
-    Tensor mV_dkl = domain_offset(make_coord(_0{}, kv_offs_0, make_coord(_0{}, kv_offs_2_1)), mV_dkl_p);
+    Tensor mV_dkl = domain_offset(make_coord(_0{}, kv_offs_0, make_coord(_0{}, _0{})), mV_dkl_p);
 
     Tensor gV_dkl = local_tile(mV_dkl, TileShapePV{}, make_coord(_, _, _), Step<X, _1, _1>{});
     Tensor tOgV_dkl = mma_pv.partition_B(gV_dkl);

csrc/sm100/fmha_cutlass_fwd_sm100.cu

@@ -18,7 +18,8 @@ void call_run_fmha_fwd([[maybe_unused]] Mask mask, [[maybe_unused]] Varlen is_va
   static constexpr bool IsVarlen = std::is_same_v<Varlen, true_type>;
   static constexpr bool IsMla = std::is_same_v<Mla, true_type>;
   static constexpr bool IsCausalMask = std::is_same_v<Mask, CausalMask<false>>;
-  using Option = std::conditional_t<IsCausalMask, Option<Tag::kIsPersistent, false_type>,
+  using Option =
+      std::conditional_t<IsCausalMask || (IsVarlen), Option<Tag::kIsPersistent, false_type>,
                          Option<Tag::kIsPersistent, true_type>>;
 
   run_fmha_fwd<Element, ElementOut, IsVarlen, IsMla, Mask, Option>(

csrc/sm100/fmha_cutlass_fwd_sm100.cuh

@@ -143,8 +143,8 @@ struct FwdRunner {
 
     ProblemShapeType problem_size_for_launch;
 
-    get<0>(problem_size_for_launch) = VariableLength{max_seqlen_q};
-    get<1>(problem_size_for_launch) = VariableLength{max_seqlen_kv};
+    get<0>(problem_size_for_launch) = VariableLength{max_seqlen_q, nullptr, total_seqlen_q};
+    get<1>(problem_size_for_launch) = VariableLength{max_seqlen_kv, nullptr, total_seqlen_kv};
     get<2>(problem_size_for_launch) = get<2>(problem_size);
     get<3>(problem_size_for_launch) = get<3>(problem_size);
 
@@ -206,10 +206,6 @@ struct FwdRunner {
                      void *q_ptr, void *k_ptr, void *v_ptr, void *o_ptr, void *lse_ptr,
                      void *cumulative_length_q, void *cumulative_length_kv) {
     auto problem_shape_ = problem_shape;
-    if constexpr (kIsVarlen) {
-      get<0>(problem_shape_).cumulative_length = static_cast<int *>(cumulative_length_q);
-      get<1>(problem_shape_).cumulative_length = static_cast<int *>(cumulative_length_kv);
-    }
 
     typename Operation::Arguments arguments{
         problem_shape_,
@@ -230,6 +226,7 @@ struct FwdRunner {
 
     int total_seqlen_q = q.size(0);
     int total_seqlen_kv = k.size(0);
+
     ProblemShapeType problem_shape =
         initialize(options, max_seqlen_q, max_seqlen_kv, total_seqlen_q, total_seqlen_kv,
                         cumulative_seqlen_q.data_ptr(), cumulative_seqlen_kv.data_ptr());
@@ -322,7 +319,7 @@ void run_fmha_fwd(at::Tensor workspace, at::Tensor q, at::Tensor k, at::Tensor v
   auto options = get_options();
 
   if (options.h % cutlass::fmha::kernel::CausalIndividualTileScheduler::TileH == 0 &&
-      (!std::is_same_v<ActiveMask, NoMask>)) {
+      (std::is_same_v<ActiveMask, CausalMask<false>> || std::is_same_v<ActiveMask, CausalMask<true>>)) {
     FwdRunner<kIsMla, true, kIsVarlen, DTypeIn, DTypeOut, ActiveMask, KernelOptions...> runner;
     runner.run(options, hw_info, q, k, v, o, lse, scale_softmax, workspace, cumulative_seqlen_q,
                cumulative_seqlen_kv, max_seqlen_q, max_seqlen_kv);

csrc/sm100/kernel/sm100_fmha_fwd_kernel_tma_warpspecialized.hpp

@@ -465,6 +465,8 @@ struct Sm100FmhaFwdKernelTmaWarpspecialized {
     else if (role == WarpRole::Correction) {
       cutlass::arch::warpgroup_reg_dealloc<NumRegsCorrection>();
 
+      bool has_valid = false;
+
       CUTLASS_PRAGMA_NO_UNROLL
       for (; tile_scheduler.is_valid(); ++tile_scheduler) {
         auto blk_coord = tile_scheduler.get_block_coord();
@@ -476,6 +478,8 @@ struct Sm100FmhaFwdKernelTmaWarpspecialized {
           continue;
         }
 
+        has_valid = true;
+
         if (get<1>(logical_problem_shape) == 0) {
           mainloop.correction_empty(
             blk_coord,
@@ -505,16 +509,17 @@ struct Sm100FmhaFwdKernelTmaWarpspecialized {
       if constexpr (NumWarpsEpilogue == 0) {
         static_assert(NumWarpsCorrection == 1);
 
+        if (has_valid) {
           uint32_t free_stage_ptr = shared_storage.tmem_base_ptr;
           tmem_allocator.free(free_stage_ptr, TmemAllocator::Sm100TmemCapacityColumns);
         }
+      }
 
     }
     else if (role == WarpRole::MMA) {
       warpgroup_reg_set<NumRegsOther>();
 
-      tmem_allocator.allocate(TmemAllocator::Sm100TmemCapacityColumns, &shared_storage.tmem_base_ptr);
-      __syncwarp();
+      bool allocated = false;
 
       CUTLASS_PRAGMA_NO_UNROLL
       for (; tile_scheduler.is_valid(); ++tile_scheduler) {
@@ -527,6 +532,12 @@ struct Sm100FmhaFwdKernelTmaWarpspecialized {
           continue;
         }
 
+        if (!allocated) {
+          tmem_allocator.allocate(TmemAllocator::Sm100TmemCapacityColumns, &shared_storage.tmem_base_ptr);
+          __syncwarp();
+          allocated = true;
+        }
+
         if (get<1>(logical_problem_shape) == 0) {
           continue;
         }
@@ -580,6 +591,8 @@ struct Sm100FmhaFwdKernelTmaWarpspecialized {
     else if (role == WarpRole::Epilogue) {
       warpgroup_reg_set<NumRegsOther>();
 
+      bool has_valid = false;
+
       CUTLASS_PRAGMA_NO_UNROLL
       for (; tile_scheduler.is_valid(); ++tile_scheduler) {
         auto blk_coord = tile_scheduler.get_block_coord();
@@ -591,6 +604,8 @@ struct Sm100FmhaFwdKernelTmaWarpspecialized {
           continue;
         }
 
+        has_valid = true;
+
         epilogue.store(
           blk_coord, logical_problem_shape,
           params.epilogue, params.problem_shape,
@@ -602,9 +617,11 @@ struct Sm100FmhaFwdKernelTmaWarpspecialized {
 
       static_assert(NumWarpsEpilogue <= 1);
       if constexpr (NumWarpsEpilogue == 1) {
+        if(has_valid) {
           uint32_t free_stage_ptr = shared_storage.tmem_base_ptr;
           tmem_allocator.free(free_stage_ptr, TmemAllocator::Sm100TmemCapacityColumns);
         }
+      }
 
     }
     else if (role == WarpRole::Empty) {

tests/test_fmha_sm100.py

@@ -82,18 +82,9 @@ def test_flash_attention(b, mean_sq, mean_sk, varlen, h, h_k, d, dv, causal, win
     grad_out = torch.randn(total_q, h, dv)
     softmax_scale = (d + 100) ** (-0.5)
 
-    offst_q = total_q
-    offst_kv = total_k
-
-    q1_with_buffer = torch.empty(total_q + total_q, h, d, device=device, dtype=dtype)
-    k1_with_buffer = torch.empty(offst_kv + total_k, h_k, d, device=device, dtype=dtype)
-    v1_with_buffer = torch.empty(offst_kv + total_k, h_k, dv, device=device, dtype=dtype)
-    q1_with_buffer[total_q:] = q
-    k1_with_buffer[offst_kv:] = k
-    v1_with_buffer[offst_kv:] = v
-    q1 = q1_with_buffer[offst_q:].requires_grad_()
-    k1 = k1_with_buffer[offst_kv:].requires_grad_()
-    v1 = v1_with_buffer[offst_kv:].requires_grad_()
+    q1 = q.clone().requires_grad_()
+    k1 = k.clone().requires_grad_()
+    v1 = v.clone().requires_grad_()
 
     q2 = q.clone().requires_grad_()
     k2 = k.clone().requires_grad_()