diff --git a/related_info/lab3/locality/Makefile b/related_info/lab3/locality/Makefile
new file mode 100644
index 0000000..62ae3a2
--- /dev/null
+++ b/related_info/lab3/locality/Makefile
@@ -0,0 +1,7 @@
+all: goodlocality badlocality
+goodlocality:
+	gcc -O0 -g -o goodlocality goodlocality.c
+badlocality:
+	gcc -O0 -g -o badlocality badlocality.c
+clean:
+	rm goodlocality badlocality
diff --git a/related_info/lab3/locality/badlocality.c b/related_info/lab3/locality/badlocality.c
new file mode 100644
index 0000000..3bd87ee
--- /dev/null
+++ b/related_info/lab3/locality/badlocality.c
@@ -0,0 +1,12 @@
+#include <stdio.h>
+#define NUM 1024
+#define COUNT 10
+int A[NUM][NUM];
+void main (void) {
+  int i,j,k;
+  for (k = 0; k<COUNT; k++)
+  for (j = 0; j < NUM; j++)
+  for (i = 0; i < NUM; i++)
+      A[i][j] = 0;
+  printf("%d count computing over!\n",i*j*k);
+}
diff --git a/related_info/lab3/locality/goodlocality.c b/related_info/lab3/locality/goodlocality.c
new file mode 100644
index 0000000..2946d32
--- /dev/null
+++ b/related_info/lab3/locality/goodlocality.c
@@ -0,0 +1,12 @@
+#include <stdio.h>
+#define NUM 1024
+#define COUNT 10
+int A[NUM][NUM];
+void main (void) {
+  int i,j,k;
+  for (k = 0; k<COUNT; k++)
+  for (i = 0; i < NUM; i++)
+  for (j = 0; j	 < NUM; j++)
+      A[i][j] = i+j;
+  printf("%d count computing over!\n",i*j*k);
+}
diff --git a/related_info/lab3/locality/locality.md b/related_info/lab3/locality/locality.md
new file mode 100644
index 0000000..2a941fc
--- /dev/null
+++ b/related_info/lab3/locality/locality.md
@@ -0,0 +1,7 @@
+#在linux下分析程序的局部性
+可通过如下命令在时间上看出在执行时间上的差异
+```
+make 
+time ./goodlocality
+time ./badlocality
+```