diff --git a/code/mperf.cc b/code/mperf.cc
index 372d113..da73f8a 100644
--- a/code/mperf.cc
+++ b/code/mperf.cc
@@ -3,39 +3,46 @@
 #include <pthread.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <sys/time.h>
+#include <time.h>
 #include <unistd.h>
 
-int cur_usage = 0;
-size_t time_base = 0;
+static size_t time_base = 0;
 
-char buf[255];
+static thread_local bool allow_record = true;
 
-bool allow_record = true;
+static const int MIN_RECORD = 32;     // 选择要记录的最小内存单元
 
-const int MIN_RECORD = 32;     // 选择要记录的最小内存单元
+static pthread_once_t init_once = PTHREAD_ONCE_INIT;
+static void *(*malloc_cp)(size_t) = nullptr;
+static void *(*realloc_cp)(void *, size_t) = nullptr;
+static void *(*calloc_cp)(size_t, size_t) = nullptr;
+static void (*free_cp)(void *) = nullptr;
 
-size_t get_cur_ms() {
-  struct timeval tv;
-  gettimeofday(&tv, NULL);
-  size_t time_stamp = tv.tv_sec * 1000 + tv.tv_usec / 1000;
-  return time_stamp;
+static size_t get_cur_ms() {
+  struct timespec ts;
+  clock_gettime(CLOCK_MONOTONIC, &ts);
+  return static_cast<size_t>(ts.tv_sec) * 1000 +
+         static_cast<size_t>(ts.tv_nsec) / 1000000;
+}
+
+static void init_real_functions() {
+  time_base = get_cur_ms();
+  malloc_cp = reinterpret_cast<void *(*)(size_t)>(dlsym(RTLD_NEXT, "malloc"));
+  realloc_cp =
+      reinterpret_cast<void *(*)(void *, size_t)>(dlsym(RTLD_NEXT, "realloc"));
+  calloc_cp =
+      reinterpret_cast<void *(*)(size_t, size_t)>(dlsym(RTLD_NEXT, "calloc"));
+  free_cp = reinterpret_cast<void (*)(void *)>(dlsym(RTLD_NEXT, "free"));
+
+  char *err = dlerror();
+  if (err != NULL) {
+    _exit(1);
+  }
 }
 
 
 void *malloc(size_t size) {
-  static int flag = 0;
-  static void *(*malloc_cp)(unsigned long);
-
-  if (flag == 0) {
-    time_base = get_cur_ms();
-    malloc_cp = (void *(*)(unsigned long))dlsym(RTLD_NEXT, "malloc");
-    char *err;
-    if ((err = dlerror()) != NULL) {
-      _exit(1);
-    }
-    flag = 1;
-  }
+  pthread_once(&init_once, init_real_functions);
 
   void *ptr = malloc_cp(size);
 
@@ -50,6 +57,7 @@ void *malloc(size_t size) {
       printf("%s ", symbols[i]);
     }
     printf("\n");
+    free_cp(symbols);
     allow_record = true;
   }
 
@@ -58,18 +66,7 @@ void *malloc(size_t size) {
 
 
 void *realloc(void *ptr, size_t size) {
-  static int flag = 0;
-  static void *(*realloc_cp)(void *, size_t);
-
-  if (flag == 0) {
-    time_base = get_cur_ms();
-    realloc_cp = (void *(*)(void *, size_t))dlsym(RTLD_NEXT, "realloc");
-    char *err;
-    if ((err = dlerror()) != NULL) {
-      _exit(1);
-    }
-    flag = 1;
-  }
+  pthread_once(&init_once, init_real_functions);
 
   void *new_ptr = realloc_cp(ptr, size);
 
@@ -84,6 +81,7 @@ void *realloc(void *ptr, size_t size) {
       printf("%s ", symbols[i]);
     }
     printf("\n");
+    free_cp(symbols);
     allow_record = true;
   }
 
@@ -91,18 +89,7 @@ void *realloc(void *ptr, size_t size) {
 }
 
 void *calloc(size_t nmemb, size_t size) {
-  static int flag = 0;
-  static void *(*calloc_cp)(size_t, size_t);
-
-  if (flag == 0) {
-    time_base = get_cur_ms();
-    calloc_cp = (void *(*)(size_t, size_t))dlsym(RTLD_NEXT, "calloc");
-    char *err;
-    if ((err = dlerror()) != NULL) {
-      _exit(1);
-    }
-    flag = 1;
-  }
+  pthread_once(&init_once, init_real_functions);
 
   void *ptr = calloc_cp(nmemb, size);
 
@@ -117,6 +104,7 @@ void *calloc(size_t nmemb, size_t size) {
       printf("%s ", symbols[i]);
     }
     printf("\n");
+    free_cp(symbols);
     allow_record = true;
   }
 
@@ -125,19 +113,7 @@ void *calloc(size_t nmemb, size_t size) {
 
 
 void free(void *ptr) {
-
-  static int flag = 0;
-  static void (*free_cp)(void *);
-
-  if (flag == 0) {
-    time_base = get_cur_ms();
-    free_cp = (void (*)(void *))dlsym(RTLD_NEXT, "free");
-    char *err;
-    if ((err = dlerror()) != NULL) {
-      _exit(1);
-    }
-    flag = 1;
-  }
+  pthread_once(&init_once, init_real_functions);
 
   if (allow_record == true) {
     allow_record = false;
diff --git a/code/mperf_less.cc b/code/mperf_less.cc
index 94addf4..6c5f8c4 100644
--- a/code/mperf_less.cc
+++ b/code/mperf_less.cc
@@ -3,39 +3,46 @@
 #include <pthread.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <sys/time.h>
+#include <time.h>
 #include <unistd.h>
 
-int cur_usage = 0;
-size_t time_base = 0;
+static size_t time_base = 0;
 
-char buf[255];
+static thread_local bool allow_record = true;
 
-bool allow_record = true;
+static const int MIN_RECORD = 0;   // 选择要记录的最小内存单元
 
-const int MIN_RECORD = 0;   // 选择要记录的最小内存单元
+static pthread_once_t init_once = PTHREAD_ONCE_INIT;
+static void *(*malloc_cp)(size_t) = nullptr;
+static void *(*realloc_cp)(void *, size_t) = nullptr;
+static void *(*calloc_cp)(size_t, size_t) = nullptr;
+static void (*free_cp)(void *) = nullptr;
 
-size_t get_cur_ms() {
-  struct timeval tv;
-  gettimeofday(&tv, NULL);
-  size_t time_stamp = tv.tv_sec * 1000 + tv.tv_usec / 1000;
-  return time_stamp;
+static size_t get_cur_ms() {
+  struct timespec ts;
+  clock_gettime(CLOCK_MONOTONIC, &ts);
+  return static_cast<size_t>(ts.tv_sec) * 1000 +
+         static_cast<size_t>(ts.tv_nsec) / 1000000;
+}
+
+static void init_real_functions() {
+  time_base = get_cur_ms();
+  malloc_cp = reinterpret_cast<void *(*)(size_t)>(dlsym(RTLD_NEXT, "malloc"));
+  realloc_cp =
+      reinterpret_cast<void *(*)(void *, size_t)>(dlsym(RTLD_NEXT, "realloc"));
+  calloc_cp =
+      reinterpret_cast<void *(*)(size_t, size_t)>(dlsym(RTLD_NEXT, "calloc"));
+  free_cp = reinterpret_cast<void (*)(void *)>(dlsym(RTLD_NEXT, "free"));
+
+  char *err = dlerror();
+  if (err != NULL) {
+    _exit(1);
+  }
 }
 
 
 void *malloc(size_t size) {
-  static int flag = 0;
-  static void *(*malloc_cp)(unsigned long);
-
-  if (flag == 0) {
-    time_base = get_cur_ms();
-    malloc_cp = (void *(*)(unsigned long))dlsym(RTLD_NEXT, "malloc");
-    char *err;
-    if ((err = dlerror()) != NULL) {
-      _exit(1);
-    }
-    flag = 1;
-  }
+  pthread_once(&init_once, init_real_functions);
 
   void *ptr = malloc_cp(size);
 
@@ -58,18 +65,7 @@ void *malloc(size_t size) {
 
 
 void *realloc(void *ptr, size_t size) {
-  static int flag = 0;
-  static void *(*realloc_cp)(void *, size_t);
-
-  if (flag == 0) {
-    time_base = get_cur_ms();
-    realloc_cp = (void *(*)(void *, size_t))dlsym(RTLD_NEXT, "realloc");
-    char *err;
-    if ((err = dlerror()) != NULL) {
-      _exit(1);
-    }
-    flag = 1;
-  }
+  pthread_once(&init_once, init_real_functions);
 
   void *new_ptr = realloc_cp(ptr, size);
 
@@ -91,18 +87,7 @@ void *realloc(void *ptr, size_t size) {
 }
 
 void *calloc(size_t nmemb, size_t size) {
-  static int flag = 0;
-  static void *(*calloc_cp)(size_t, size_t);
-
-  if (flag == 0) {
-    time_base = get_cur_ms();
-    calloc_cp = (void *(*)(size_t, size_t))dlsym(RTLD_NEXT, "calloc");
-    char *err;
-    if ((err = dlerror()) != NULL) {
-      _exit(1);
-    }
-    flag = 1;
-  }
+  pthread_once(&init_once, init_real_functions);
 
   void *ptr = calloc_cp(nmemb, size);
 
@@ -125,19 +110,7 @@ void *calloc(size_t nmemb, size_t size) {
 
 
 void free(void *ptr) {
-
-  static int flag = 0;
-  static void (*free_cp)(void *);
-
-  if (flag == 0) {
-    time_base = get_cur_ms();
-    free_cp = (void (*)(void *))dlsym(RTLD_NEXT, "free");
-    char *err;
-    if ((err = dlerror()) != NULL) {
-      _exit(1);
-    }
-    flag = 1;
-  }
+  pthread_once(&init_once, init_real_functions);
 
   if (allow_record == true) {
     allow_record = false;