diff --git a/src/mat.h b/src/mat.h
index 1cbce635bbd..4a24c631e0b 100644
--- a/src/mat.h
+++ b/src/mat.h
@@ -862,13 +862,13 @@ NCNN_FORCEINLINE Mat::Mat(int _w, int _h, void* _data, size_t _elemsize, Allocat
 NCNN_FORCEINLINE Mat::Mat(int _w, int _h, int _c, void* _data, size_t _elemsize, Allocator* _allocator)
     : data(_data), refcount(0), elemsize(_elemsize), elempack(1), allocator(_allocator), dims(3), w(_w), h(_h), d(1), c(_c)
 {
-    cstep = alignSize((size_t)w * h * elemsize, 16) / elemsize;
+    cstep = alignSize((size_t)w * h * elemsize, 128) / elemsize;
 }
 
 NCNN_FORCEINLINE Mat::Mat(int _w, int _h, int _d, int _c, void* _data, size_t _elemsize, Allocator* _allocator)
     : data(_data), refcount(0), elemsize(_elemsize), elempack(1), allocator(_allocator), dims(4), w(_w), h(_h), d(_d), c(_c)
 {
-    cstep = alignSize((size_t)w * h * d * elemsize, 16) / elemsize;
+    cstep = alignSize((size_t)w * h * d * elemsize, 128) / elemsize;
 }
 
 NCNN_FORCEINLINE Mat::Mat(int _w, void* _data, size_t _elemsize, int _elempack, Allocator* _allocator)
@@ -886,13 +886,13 @@ NCNN_FORCEINLINE Mat::Mat(int _w, int _h, void* _data, size_t _elemsize, int _el
 NCNN_FORCEINLINE Mat::Mat(int _w, int _h, int _c, void* _data, size_t _elemsize, int _elempack, Allocator* _allocator)
     : data(_data), refcount(0), elemsize(_elemsize), elempack(_elempack), allocator(_allocator), dims(3), w(_w), h(_h), d(1), c(_c)
 {
-    cstep = alignSize((size_t)w * h * elemsize, 16) / elemsize;
+    cstep = alignSize((size_t)w * h * elemsize, 128) / elemsize;
 }
 
 NCNN_FORCEINLINE Mat::Mat(int _w, int _h, int _d, int _c, void* _data, size_t _elemsize, int _elempack, Allocator* _allocator)
     : data(_data), refcount(0), elemsize(_elemsize), elempack(_elempack), allocator(_allocator), dims(4), w(_w), h(_h), d(_d), c(_c)
 {
-    cstep = alignSize((size_t)w * h * d * elemsize, 16) / elemsize;
+    cstep = alignSize((size_t)w * h * d * elemsize, 128) / elemsize;
 }
 
 NCNN_FORCEINLINE Mat::~Mat()
@@ -1446,13 +1446,13 @@ NCNN_FORCEINLINE VkMat::VkMat(int _w, int _h, VkBufferMemory* _data, size_t _ele
 NCNN_FORCEINLINE VkMat::VkMat(int _w, int _h, int _c, VkBufferMemory* _data, size_t _elemsize, VkAllocator* _allocator)
     : data(_data), refcount(0), elemsize(_elemsize), elempack(1), allocator(_allocator), dims(3), w(_w), h(_h), d(1), c(_c)
 {
-    cstep = alignSize(w * h * elemsize, 16) / elemsize;
+    cstep = alignSize(w * h * elemsize, 128) / elemsize;
 }
 
 NCNN_FORCEINLINE VkMat::VkMat(int _w, int _h, int _d, int _c, VkBufferMemory* _data, size_t _elemsize, VkAllocator* _allocator)
     : data(_data), refcount(0), elemsize(_elemsize), elempack(1), allocator(_allocator), dims(4), w(_w), h(_h), d(_d), c(_c)
 {
-    cstep = alignSize(w * h * d * elemsize, 16) / elemsize;
+    cstep = alignSize(w * h * d * elemsize, 128) / elemsize;
 }
 
 NCNN_FORCEINLINE VkMat::VkMat(int _w, VkBufferMemory* _data, size_t _elemsize, int _elempack, VkAllocator* _allocator)
@@ -1470,13 +1470,13 @@ NCNN_FORCEINLINE VkMat::VkMat(int _w, int _h, VkBufferMemory* _data, size_t _ele
 NCNN_FORCEINLINE VkMat::VkMat(int _w, int _h, int _c, VkBufferMemory* _data, size_t _elemsize, int _elempack, VkAllocator* _allocator)
     : data(_data), refcount(0), elemsize(_elemsize), elempack(_elempack), allocator(_allocator), dims(3), w(_w), h(_h), d(1), c(_c)
 {
-    cstep = alignSize(w * h * elemsize, 16) / elemsize;
+    cstep = alignSize(w * h * elemsize, 128) / elemsize;
 }
 
 NCNN_FORCEINLINE VkMat::VkMat(int _w, int _h, int _d, int _c, VkBufferMemory* _data, size_t _elemsize, int _elempack, VkAllocator* _allocator)
     : data(_data), refcount(0), elemsize(_elemsize), elempack(_elempack), allocator(_allocator), dims(4), w(_w), h(_h), d(_d), c(_c)
 {
-    cstep = alignSize(w * h * d * elemsize, 16) / elemsize;
+    cstep = alignSize(w * h * d * elemsize, 128) / elemsize;
 }
 
 NCNN_FORCEINLINE VkMat::~VkMat()