speed_up for deformable conv (#46997)

paddle/phi/kernels/impl/deformable_conv_kernel_impl.h

@@ -19,6 +19,7 @@
 #include "paddle/phi/kernels/empty_kernel.h"
 #include "paddle/phi/kernels/funcs/blas/blas.h"
 #include "paddle/phi/kernels/funcs/deformable_conv_functor.h"
+#include "paddle/phi/kernels/transpose_kernel.h"
 #include "paddle/utils/optional.h"
 
 namespace phi {
@@ -38,6 +39,11 @@ void DeformableConvKernel(const Context& dev_ctx,
                           DenseTensor* out) {
   const int batch_size = static_cast<int>(x.dims()[0]);
 
+  int temp_step = std::min(64, batch_size);
+  if (batch_size % temp_step == 0) {
+    im2col_step = temp_step;
+  }
+
   std::vector<int64_t> filter_shape_vec(phi::vectorize(filter.dims()));
   std::vector<int64_t> output_shape_vec(phi::vectorize(out->dims()));
 
@@ -101,8 +107,11 @@ void DeformableConvKernel(const Context& dev_ctx,
         dilations,
         deformable_groups,
         col_buffer_ptr);
-    DenseTensor output_3d = output_4d.Slice(i, i + 1).Resize(
-        phi::slice_ddim(output_4d.dims(), 1, output_4d.dims().size()));
+    DenseTensor output_3d = output_4d.Slice(i, i + 1).Resize(phi::slice_ddim(
+        output_4d.dims(),
+        1,
+        output_4d.dims().size()));  // group * C/group * (im2step * H * W)
+
     // get the product of pixel and weight
     for (int g = 0; g < groups; ++g) {
       DenseTensor weight_3d_slice = weight_3d.Slice(g, g + 1).Resize(
@@ -110,8 +119,11 @@ void DeformableConvKernel(const Context& dev_ctx,
       DenseTensor col_buffer_3d_slice =
           col_buffer_3d.Slice(g, g + 1).Resize(phi::slice_ddim(
               col_buffer_3d.dims(), 1, col_buffer_3d.dims().size()));
-      DenseTensor output_3d_slice = output_3d.Slice(g, g + 1).Resize(
-          phi::slice_ddim(output_3d.dims(), 1, output_3d.dims().size()));
+      DenseTensor output_3d_slice =
+          output_3d.Slice(g, g + 1).Resize(phi::slice_ddim(
+              output_3d.dims(),
+              1,
+              output_3d.dims().size()));  // C * ((im2col_step)*H*W))
       blas.MatMul(weight_3d_slice,
                   false,
                   col_buffer_3d_slice,
@@ -121,7 +133,29 @@ void DeformableConvKernel(const Context& dev_ctx,
                   T(0.0));
     }
   }
+
+  //  swap axis to get the right result when im2col_step is greater than 1
+  if (im2col_step > 1) {
+    std::vector<int> axis(4);
+    axis[0] = 0;
+    axis[1] = 2;
+    axis[2] = 1;
+    axis[3] = 3;
+
+    DenseTensor real_output_buffer = phi::Transpose<T, Context>(
+        dev_ctx,
+        output_4d.Resize(
+            phi::make_ddim({batch_size / im2col_step,
+                            output_shape_vec[1],
+                            im2col_step,
+                            output_shape_vec[2] * output_shape_vec[3]})),
+        axis);
+
+    out->ShareDataWith(real_output_buffer)
+        .Resize(phi::make_ddim(output_shape_vec));
+  } else {
     out->ShareDataWith(output_buffer).Resize(phi::make_ddim(output_shape_vec));
+  }
 }
 
 }  // namespace phi