Optimize layer norm forward when cols is 1024. (#39167)

* Optimize layer_norm fwd when cols is 1024.

paddle/fluid/operators/fused/fused_layernorm_residual_dropout_bias.h

@@ -19,6 +19,8 @@ limitations under the License. */
 namespace paddle {
 namespace operators {
 
+#define LN_NUM_COLS 1024
+
 template <typename T>
 using CudnnDataType = platform::CudnnDataType<T>;
 template <typename T>
@@ -153,6 +155,191 @@ __global__ void FusedLayernormResidualDropoutBias(
       invvar);
 }
 
+/*
+* @brief layernorm(residual + dropout(x));
+ * Conditions:
+ * (1) The number of cols is 1024;
+ * (2) layer_norm scale and bias is not null;
+ * (3) linear bias is null;
+ * @param
+ * rows: batch_size * seq_len
+ * cols: 1024
+ * x_: [rows, cols], inputs
+ * residual_:[rows, cols]
+ * gamma_: [cols]: layernorm scale, not null
+ * beta_: [cols], layernorm bias, not null
+ * mask_out_: [rows, cols], dropout result
+ * residual_out_: [rows, cols], residual + dropout(src)
+ * y_: [rows, cols], layernorm result
+ * mean_out_: [rows]: layernorm means
+ * var_out_: [rows]: layernorm vars
+*/
+template <
+    typename T, typename U, typename ScaleT = U, typename MaskType = uint8_t,
+    int VecSize = 8, int WARPS_M = 4, int WARPS_N = 1, int BYTES_PER_LDG = 16,
+    int ELTS_PER_ROW = 1024, int THREADS_PER_WARP = 32,
+    int THREADS_PER_ROW = WARPS_N *THREADS_PER_WARP,
+    int THREADS_PER_CTA = WARPS_M *THREADS_PER_ROW, int ROWS_PER_CTA = WARPS_M,
+    int ELTS_PER_ROW_PER_CTA = THREADS_PER_ROW *VecSize,
+    int LDGS = ELTS_PER_ROW / ELTS_PER_ROW_PER_CTA>
+__global__ __launch_bounds__(THREADS_PER_CTA) void fused_ln_fwd_1024_kernel(
+    int rows, int cols, uint64_t seed, const float dropout_prob,
+    const bool is_upscale_in_train, const bool is_test,
+    const uint64_t increment, const float epsilon, const T *__restrict__ x_ptr,
+    const T *__restrict__ residual_ptr, const ScaleT *__restrict__ gamma_ptr,
+    const ScaleT *__restrict__ beta_ptr, MaskType *__restrict__ mask_out_ptr,
+    U *__restrict__ mean_out_ptr, U *__restrict__ var_out_ptr,
+    T *__restrict__ residual_out_ptr, T *__restrict__ y_ptr) {
+  using Vec = platform::AlignedVector<T, VecSize>;
+  using Vec_scale = platform::AlignedVector<ScaleT, VecSize>;
+  using MaskStoreT = platform::AlignedVector<MaskType, VecSize>;
+
+  const int tidx = threadIdx.x;
+  const int bidx = blockIdx.x;
+  const int lane = tidx % THREADS_PER_WARP;  // 0, 1, ..., 31
+  const int warp = tidx / THREADS_PER_WARP;  // 0, 1, 2, 3
+  const int warp_n = warp % WARPS_N;         // 0
+  const int warp_m = warp / WARPS_N;         // 0, 1, 2, 3
+
+  const int c = warp_n * THREADS_PER_WARP + lane;  // lane
+  const int r = bidx * ROWS_PER_CTA + warp_m;      // row id
+
+  int idx = r * LN_NUM_COLS + c;
+  curandStatePhilox4_32_10_t state;
+  curand_init(seed, idx, increment, &state);
+
+  T factor = GetFactor<T>(dropout_prob, is_upscale_in_train, is_test);
+
+  Vec_scale gamma[LDGS];
+  Vec_scale beta[LDGS];
+#pragma unroll
+  for (int it = 0, col = c; it < LDGS; it++) {
+    platform::Load<ScaleT, VecSize>(gamma_ptr + col * VecSize, &gamma[it]);
+    platform::Load<ScaleT, VecSize>(beta_ptr + col * VecSize, &beta[it]);
+    col += THREADS_PER_ROW;
+  }
+
+  constexpr U rn = 1.f / U(LN_NUM_COLS);
+  for (int row = r; row < rows; row += gridDim.x * ROWS_PER_CTA) {
+    Vec x[LDGS];
+    Vec residual[LDGS];
+#pragma unroll
+    for (int it = 0, col = c; it < LDGS; it++) {
+      platform::Load<T, VecSize>(x_ptr + row * LN_NUM_COLS + col * VecSize,
+                                 &x[it]);
+      platform::Load<T, VecSize>(
+          residual_ptr + row * LN_NUM_COLS + col * VecSize, &residual[it]);
+      col += THREADS_PER_ROW;
+    }
+
+    MaskStoreT mask_vec[LDGS];
+    if (!is_test) {
+#pragma unroll
+      for (int it = 0; it < LDGS; it++) {
+        float rand[VecSize];
+        RandVec<VecSize>(&state, rand);
+#pragma unroll
+        for (int jt = 0; jt < VecSize; jt++) {
+#pragma unroll
+          mask_vec[it][jt] = static_cast<MaskType>(rand[jt] >= dropout_prob);
+        }
+      }
+    } else {
+#pragma unroll
+      for (int it = 0; it < LDGS; it++) {
+#pragma unroll
+        for (int jt = 0; jt < VecSize; jt++) {
+          mask_vec[it][jt] = static_cast<MaskType>(1);
+        }
+      }
+    }
+
+    // 4 * 8
+    U xf[LDGS * VecSize];
+#pragma unroll
+    for (int it = 0; it < LDGS; it++) {
+#pragma unroll
+      for (int jt = 0; jt < VecSize; jt++) {
+        // dropout(x) + residual
+        x[it][jt] = x[it][jt] * static_cast<T>(mask_vec[it][jt]) * factor +
+                    residual[it][jt];
+        xf[it * VecSize + jt] = U(x[it][jt]);
+      }
+    }
+
+// store dropout_residual_out and mask_out
+#pragma unroll
+    for (int it = 0, col = c; it < LDGS; it++) {
+      platform::Store<T, VecSize>(
+          x[it], residual_out_ptr + row * LN_NUM_COLS + col * VecSize);
+      platform::Store<MaskType, VecSize>(
+          mask_vec[it], mask_out_ptr + row * LN_NUM_COLS + col * VecSize);
+      col += THREADS_PER_ROW;
+    }
+
+    U mu_local = 0.f;
+#pragma unroll
+    for (int it = 0; it < LDGS; it++) {
+#pragma unroll
+      for (int jt = 0; jt < VecSize; jt++) {
+        mu_local += xf[it * VecSize + jt];
+      }
+    }
+
+#pragma unroll
+    for (int it = 1; it < THREADS_PER_WARP; it *= 2) {
+      mu_local += __shfl_xor_sync(uint32_t(-1), mu_local, it);
+    }
+    mu_local *= rn;
+    if (lane == 0) {
+      mean_out_ptr[row] = mu_local;
+    }
+    U var_local = 0.f;
+
+#pragma unroll
+    for (int it = 0; it < LDGS; it++) {
+#pragma unroll
+      for (int jt = 0; jt < VecSize; jt++) {
+        U diff = xf[it * VecSize + jt] - mu_local;
+        var_local += diff * diff;
+      }
+    }
+
+#pragma unroll
+    for (int it = 1; it < THREADS_PER_WARP; it *= 2) {
+      var_local += __shfl_xor_sync(uint32_t(-1), var_local, it);
+    }
+    U rsigma = rsqrtf(var_local * rn + epsilon);
+    if (lane == 0) {
+      // Note: the stored var is different for paddle(ln) and apex (fast ln).
+      // var_out_ptr[row] = rsigma;
+      var_out_ptr[row] = var_local * rn;
+    }
+
+#pragma unroll
+    for (int it = 0; it < LDGS; it++) {
+#pragma unroll
+      for (int jt = 0; jt < VecSize; jt++) {
+        // use fp16 to compute
+        // ScaleT tmp = static_cast<ScaleT>(rsigma * (xf[it * VecSize + jt] -
+        // mu_local));
+        // x[it][jt] = gamma[it][jt] *  tmp + beta[it][jt];
+        // cast to fp32 to compute
+        U tmp = rsigma * (static_cast<U>(xf[it * VecSize + jt]) - mu_local);
+        x[it][jt] = static_cast<T>(static_cast<U>(gamma[it][jt]) * tmp +
+                                   static_cast<U>(beta[it][jt]));
+      }
+    }
+
+#pragma unroll
+    for (int it = 0, col = c; it < LDGS; it++) {
+      platform::Store<T, VecSize>(x[it],
+                                  y_ptr + row * LN_NUM_COLS + col * VecSize);
+      col += THREADS_PER_ROW;
+    }
+  }
+}
+
 /**
  * @brief layernorm(residual + dropout(src + bias));
  * @param
@@ -205,6 +392,13 @@ void LaunchLayernormResidualDropoutBias(
     return;
   }
 
+  bool can_call_1024_kernel = false;
+  if (cols == 1024 && scale != nullptr && layernorm_bias != nullptr &&
+      bias == nullptr) {
+    can_call_1024_kernel = true;
+  }
+  VLOG(6) << "can_call_1024_kernel = " << can_call_1024_kernel;
+
   const int VecSize = MAX_CACHE_BYTES / sizeof(T);
   if (cols % VecSize != 0) {
     int blockDim = GetDesiredBlockDim(cols);
@@ -215,13 +409,35 @@ void LaunchLayernormResidualDropoutBias(
         epsilon, src, residual, bias, scale, layernorm_bias, mask_data, dst,
         layernorm_dst, mean, var);
   } else {
-    int blockDim = GetDesiredBlockDim(cols / VecSize);
-    FusedLayernormResidualDropoutBias<
-        T, uint8_t, VecSize, U,
-        ScaleBiasWithSameTypeX><<<rows, blockDim, 0, ctx.stream()>>>(
-        rows, cols, seed, dropout_prob, is_upscale_in_train, is_test, increment,
-        epsilon, src, residual, bias, scale, layernorm_bias, mask_data, dst,
-        layernorm_dst, mean, var);
+    if (can_call_1024_kernel) {
+      const int WARPS_M = 4;
+      const int WARPS_N = 1;
+      const int THREADS_PER_WARP = 32;
+      const int BYTES_PER_LDG = 16;
+      const int VecSize = BYTES_PER_LDG / sizeof(T);
+
+      const int THREADS_PER_CTA = WARPS_N * THREADS_PER_WARP * WARPS_M;
+      const int ROWS_PER_CTA = WARPS_M;
+
+      // Note: the grid can not exceed max_grid of the gpu.
+      const int grid =
+          static_cast<int>(std::ceil(rows / static_cast<float>(ROWS_PER_CTA)));
+      fused_ln_fwd_1024_kernel<
+          T, U, LayerNormScaleBiasT<T, U, ScaleBiasWithSameTypeX>, uint8_t,
+          VecSize, WARPS_M, WARPS_N,
+          BYTES_PER_LDG><<<grid, THREADS_PER_CTA, 0, ctx.stream()>>>(
+          rows, cols, seed, dropout_prob, is_upscale_in_train, is_test,
+          increment, epsilon, src, residual, scale, layernorm_bias, mask_data,
+          mean, var, dst, layernorm_dst);
+    } else {
+      int blockDim = GetDesiredBlockDim(cols / VecSize);
+      FusedLayernormResidualDropoutBias<
+          T, uint8_t, VecSize, U,
+          ScaleBiasWithSameTypeX><<<rows, blockDim, 0, ctx.stream()>>>(
+          rows, cols, seed, dropout_prob, is_upscale_in_train, is_test,
+          increment, epsilon, src, residual, bias, scale, layernorm_bias,
+          mask_data, dst, layernorm_dst, mean, var);
+    }
   }
 }
 

paddle/fluid/operators/fused/fused_layernorm_residual_dropout_bias_test.cu

@@ -66,20 +66,18 @@ struct TestFusedLayernormResidualDropoutBias {
     ctx = reinterpret_cast<platform::CUDADeviceContext *>(devicectx);
   }
 
-  TestFusedLayernormResidualDropoutBias(int _rows, int _cols,
-                                        uint64_t _seed = 0,
-                                        float _dropout_prob = 0.0,
-                                        float _epsilon = 0.00001f,
-                                        bool _is_upscale_in_train = false,
-                                        bool _is_test = false) {
+  TestFusedLayernormResidualDropoutBias(
+      int _rows, int _cols, uint64_t _seed = 0, float _dropout_prob = 0.0,
+      float _epsilon = 0.00001f, bool _is_upscale_in_train = false,
+      bool _is_test = false, bool _has_bias = true) {
     rows = _rows;
     cols = _cols;
     seed = _seed;
     dropout_prob = _dropout_prob;
     epsilon = _epsilon;
     is_upscale_in_train = _is_upscale_in_train;
     is_test = _is_test;
-    has_bias = true;
+    has_bias = _has_bias;
     has_scale = true;
     has_layernorm_bias = true;
     platform::DeviceContextPool &pool = platform::DeviceContextPool::Instance();
@@ -283,7 +281,6 @@ static void BaseTest(const bool is_fp16 = false) {
     }
   }
 }
-
 TEST(FusedDropout, GPUFusedLayernormResidualDropoutBias) { BaseTest<float>(); }
 
 TEST(FusedDropout, GPUFusedLayernormResidualDropoutBiasDouble) {
@@ -330,3 +327,12 @@ TEST(FusedDropout, GPUFusedLayernormResidualDropoutLargeShape) {
   test.Run();
   test.CheckOut(static_cast<float>(1e-4));
 }
+
+TEST(FusedDropout, GPUFusedLayernormResidualDropoutFp16MLperf) {
+  const int rows = 512;
+  const int cols = 1024;
+  TestFusedLayernormResidualDropoutBias<platform::float16> test(
+      rows, cols, 0, 0, 0.00001f, false, false, false);
+  test.Run();
+  test.CheckOut(static_cast<platform::float16>(1e-2));
+}