diff --git a/example/ck_tile/20_grouped_convolution/grouped_convolution_backward_weight.cpp b/example/ck_tile/20_grouped_convolution/grouped_convolution_backward_weight.cpp
index 3d0d504427..5775acaf0d 100644
--- a/example/ck_tile/20_grouped_convolution/grouped_convolution_backward_weight.cpp
+++ b/example/ck_tile/20_grouped_convolution/grouped_convolution_backward_weight.cpp
@@ -29,16 +29,19 @@ float grouped_conv_bwd_weight(const ck_tile::GroupedConvBwdWeightHostArgs& args,
 {
     constexpr int kBlockPerCu = 1;
 
-    constexpr ck_tile::index_t M_Tile = 64;
-    constexpr ck_tile::index_t N_Tile = 64;
+    // Block tile: <MPerBlock, NPerBlock, KPerBlock>
+    // Note that we must satisfy 
+    // - MIterPerWarp * MWarp * WarpGemm::kM == MPerBlock
+    constexpr ck_tile::index_t M_Tile = 8; //64
+    constexpr ck_tile::index_t N_Tile = 128;
     constexpr ck_tile::index_t K_Tile = 64;
 
     constexpr ck_tile::index_t M_Warp = 2;
     constexpr ck_tile::index_t N_Warp = 2;
     constexpr ck_tile::index_t K_Warp = 1;
 
-    constexpr ck_tile::index_t M_Warp_Tile = 32;
-    constexpr ck_tile::index_t N_Warp_Tile = 32;
+    constexpr ck_tile::index_t M_Warp_Tile = 4; // 32
+    constexpr ck_tile::index_t N_Warp_Tile = 64; // 32
     constexpr ck_tile::index_t K_Warp_Tile = 16;
 
     constexpr ck_tile::index_t VectorSizeA = 8;