diff --git a/threads/lock_performance/Makefile b/threads/lock_performance/Makefile
new file mode 100755
index 0000000..8f2c49e
--- /dev/null
+++ b/threads/lock_performance/Makefile
@@ -0,0 +1,8 @@
+all: lock_performance
+	gcc lock_performance.c -o lock_performance
+
+clean:
+	rm lock_performance
+
+test:
+	./lock_performance
diff --git a/threads/lock_performance/README.md b/threads/lock_performance/README.md
new file mode 100755
index 0000000..84200e0
--- /dev/null
+++ b/threads/lock_performance/README.md
@@ -0,0 +1,37 @@
+Threading Examples
+=======
+wenhui-2:threads WenhuiZhang$ ./lock_performance
+-----------------------------
+lock performance for 1 thread with 10000 loops
+Total time cost by running 1 threads for increase function with lock implementation: 0.000686
+secStarting of the program, start_t = 2327
+End of the process end_t = 3138
+Total time cost by running 1 threads for increase function without lock implementation: 0.000092 sec
+Mutex Time Cost by running 1 threads for increase function: 0.000594 sec
+Per thread Mutex Time Cost by running 1 threads for increase function: 0.000594 sec
+-----------------------------
+lock performance for 2 thread with 10000 loops
+Total time cost by running 2 threads for increase function with lock implementation: 0.048873
+secStarting of the program, start_t = 3170
+End of the process end_t = 52294
+Total time cost by running 2 threads for increase function without lock implementation: 0.000227 sec
+Mutex Time Cost by running 2 threads for increase function: 0.048646 sec
+Per thread Mutex Time Cost by running 2 threads for increase function: 0.024323 sec
+-----------------------------
+lock performance for 4 thread with 10000 loops
+Total time cost by running 4 threads for increase function with lock implementation: 0.173181
+secStarting of the program, start_t = 52315
+End of the process end_t = 225927
+Total time cost by running 4 threads for increase function without lock implementation: 0.000407 sec
+Mutex Time Cost by running 4 threads for increase function: 0.172774 sec
+Per thread Mutex Time Cost by running 4 threads for increase function: 0.043194 sec
+-----------------------------
+-----------------------------
+lock performance for 16 thread with 10000 loops
+Total time cost by running 16 threads for increase function with lock implementation: 0.664478
+secStarting of the program, start_t = 225953
+End of the process end_t = 892292
+Total time cost by running 16 threads for increase function without lock implementation: 0.001840 sec
+Mutex Time Cost by running 16 threads for increase function: 0.662638 sec
+Per thread Mutex Time Cost by running 16 threads for increase function: 0.041415 sec
+-----------------------------
\ No newline at end of file
diff --git a/threads/lock_performance/lock_performance.c b/threads/lock_performance/lock_performance.c
new file mode 100755
index 0000000..8eb3f19
--- /dev/null
+++ b/threads/lock_performance/lock_performance.c
@@ -0,0 +1,184 @@
+/*
+ * measures the performance cost by time of using locks in multi-thread program
+ * Measure the overhead of calling lock and unlock depending on the level of contention
+ * by utilizing clock(), in time.h
+ * Author: Wenhui Zhang， Hu Yang, Pradeep
+ */
+
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <time.h>
+
+
+
+int ctr;
+pthread_mutex_t count_mutex;
+clock_t start_t, end_t, acc_lock_t, acc_no_lock_t;
+
+
+
+/* thread_lock: thread function for multi-thread generation */
+void thread_lock()
+{
+    
+    for (int i = 0; i < 10000; i++){
+        pthread_mutex_lock(&count_mutex);
+        ctr = ctr + 1;
+        //printf("%d \n", ctr);
+    
+        pthread_mutex_unlock(&count_mutex);
+       
+    }
+
+    
+}
+
+
+/* thread_no_lock: thread function for multi-thread generation */
+void thread_no_lock()
+{
+    
+    for (int i = 0; i < 10000; i++){
+        ctr = ctr + 1;
+        //printf("%d \n", ctr);
+    }
+    
+    
+}
+
+
+
+
+
+int lock_performance(int num_threads)
+{
+    
+    acc_lock_t = 0;
+    acc_no_lock_t = 0;
+    double total_t_lock, total_t_unlock; //time counter
+    int rc;
+    int tnum; //counter for threads
+
+    
+    
+    
+    pthread_t  thread_info[num_threads];	// thread identifier
+    
+    /* Test for thread_incr_lock */
+    
+    
+    
+    start_t = clock();
+    for (tnum = 0; tnum < num_threads; tnum++){
+        //printf("create thread %d\n", tnum);
+        
+        rc = pthread_create(&thread_info[tnum], NULL, (void*)&thread_lock, NULL);
+        if (rc){
+            printf("ERROR; return code from pthread_create() is %d\n", rc);
+            exit(1);
+        }
+    }
+    
+    
+    for (tnum = 0; tnum < num_threads; tnum++){
+        pthread_join(thread_info[tnum], NULL);
+    }
+    
+    
+    end_t = clock();
+    total_t_lock = (double)((end_t - start_t) / (double)CLOCKS_PER_SEC);
+    printf("Total time cost by running %d threads for increase function with lock implementation: %f\n sec", num_threads, total_t_lock);
+    
+    
+    
+    /* Test for thread_incr_unlock */
+    
+    ctr = 0;
+    
+    printf("Starting of the program, start_t = %ld\n", start_t);
+    
+    start_t = clock();
+    for (tnum = 0; tnum < num_threads; tnum++){
+        //printf("create thread %d\n", tnum);
+        
+        rc = pthread_create(&thread_info[tnum], NULL, (void*)&thread_no_lock, NULL);
+        if (rc){
+            printf("ERROR; return code from pthread_create() is %d\n", rc);
+            exit(1);
+        }
+    }
+    
+    
+    for (tnum = 0; tnum < num_threads; tnum++){
+        pthread_join(thread_info[tnum], NULL);
+    }
+    
+    
+    end_t = clock();
+    
+    printf("End of the process end_t = %ld\n", end_t);
+    total_t_unlock = (double)((end_t - start_t) / (double)CLOCKS_PER_SEC);
+    printf("Total time cost by running %d threads for increase function without lock implementation: %f sec\n", num_threads, total_t_unlock);
+    
+    
+    
+    
+    printf("Mutex Time Cost by running %d threads for increase function: %f sec\n", num_threads, total_t_lock - total_t_unlock);
+    printf("Per thread Mutex Time Cost by running %d threads for increase function: %f sec\n ", num_threads,(total_t_lock - total_t_unlock)/(double)num_threads);
+
+    
+    
+    return 0;
+}
+
+
+int main(void)
+{
+    pthread_mutex_init(&count_mutex, NULL); //initialize mutex
+    
+    printf("-----------------------------\n");
+    printf("lock performance for 1 thread with 10000 loops\n");
+    
+    lock_performance(1);
+    
+    
+    printf("-----------------------------\n");
+    printf("lock performance for 2 thread with 10000 loops\n");
+    
+    lock_performance(2);
+    
+    
+    printf("-----------------------------\n");
+    printf("lock performance for 4 thread with 10000 loops\n");
+    
+    
+    lock_performance(4);
+    printf("-----------------------------\n");
+    
+  
+    
+    
+    
+    
+    printf("-----------------------------\n");
+    printf("lock performance for 16 thread with 10000 loops\n");
+    
+    
+    lock_performance(16);
+    printf("-----------------------------\n");
+    
+    pthread_mutex_destroy(&count_mutex); // destroy mutex
+
+    
+    return 0;
+}
+
+
+
+
+
+
+