enable packing_layout by default

src/option.cpp

@@ -41,7 +41,7 @@ Option::Option()
     use_int8_storage = true;
     use_int8_arithmetic = false;
 
-    use_packing_layout = false;
+    use_packing_layout = true;
 
     use_shader_pack8 = false;
 

src/option.h

@@ -85,12 +85,16 @@ public:
     bool use_int8_storage;
     bool use_int8_arithmetic;
 
-    //
+    // enable simd-friendly packed memory layout
+    // improve all operator performace on all arm devices, will consume more memory
+    // changes should be applied before loading network structure and weight
+    // enabled by default
     bool use_packing_layout;
 
     bool use_shader_pack8;
 
-    // enable options for cpu inference
+    // enable bf16 data type for storage
+    // improve most operator performace on all arm devices, may consume more memory
     bool use_bf16_storage;
 };