diff --git a/src/listhead.rs b/src/listhead.rs
index dde7f55..ab6645b 100644
--- a/src/listhead.rs
+++ b/src/listhead.rs
@@ -101,8 +101,8 @@ impl<T> ListHead<T> {
 
     pub fn replace_init(head: &Rc::<RefCell::<Self>>, pnew: &Rc::<RefCell::<Self>>) {
         if !head.borrow().empty() {
-            let timer = &head.borrow().first_entry();
-            let a = timer.upgrade().unwrap();
+            //let timer = &head.borrow().first_entry();
+            //let a = timer.upgrade().unwrap();
         } else {
             return;
         }
@@ -113,8 +113,8 @@ impl<T> ListHead<T> {
         pnew.borrow_mut().prev.upgrade().unwrap().borrow_mut().next = Rc::downgrade(pnew);
         head.borrow_mut().init();
         if !pnew.borrow().empty() {
-            let timer = &pnew.borrow().first_entry();
-            let a = timer.upgrade().unwrap();
+            //let timer = &pnew.borrow().first_entry();
+            //let a = timer.upgrade().unwrap();
         }
     }
 
diff --git a/src/xtimer.rs b/src/xtimer.rs
index 2617fa3..f81d9a3 100644
--- a/src/xtimer.rs
+++ b/src/xtimer.rs
@@ -227,7 +227,7 @@ impl XTimer {
         }
         println!("zzzzzzz idx:{} index:{}", idx, index);
         if !tv[index].borrow().empty() {
-            let mut cascade_list = crate::ListHead::<TimerList>::new_head();
+            let cascade_list = crate::ListHead::<TimerList>::new_head();
             crate::ListHead::<TimerList>::replace_init
                 (&tv[index],
                  &cascade_list);
@@ -245,15 +245,7 @@ impl XTimer {
     }
 
     pub fn update(&mut self) {
-        let mut tick = 0;
-        match &self.get_tick_count {
-            Some(v) => {
-                tick = (*v)();
-            }
-            None => {
-
-            }
-        }
+        let tick = (*self.get_tick_count.as_ref().unwrap())();
         while tick >= self.timer_tick {
             let index = (self.timer_tick & (TVR_MASK as i64)) as usize;
             if index == 0 &&
@@ -263,7 +255,6 @@ impl XTimer {
                     self.cascade(3);
                 }
             self.timer_tick += 1;
-            println!("wwwwwwwwwwww");
 
             //println!("timer_tick:{} index:{} empty:{}", self.timer_tick, index, self.tv1[index].borrow().empty());
             crate::ListHead::<TimerList>::replace_init
@@ -272,7 +263,7 @@ impl XTimer {
             while !self.work_list.borrow().empty() {
                 let timer = &self.work_list.borrow().first_entry();
                 self.running_timer = timer.clone();
-                let a = timer.upgrade().unwrap();
+                //let a = timer.upgrade().unwrap();
                 match &mut timer.upgrade().unwrap().borrow_mut().cb {
                     Some(v) => {
                         (*v)(TimerEvent::Exec, None);