diff --git a/crate/thread/src/scheduler/mod.rs b/crate/thread/src/scheduler/mod.rs
index 04e56fd..8d6367f 100644
--- a/crate/thread/src/scheduler/mod.rs
+++ b/crate/thread/src/scheduler/mod.rs
@@ -15,8 +15,6 @@ type Pid = usize;
 pub trait Scheduler: Sync + 'static {
     /// Push a thread to the back of ready queue.
     fn push(&self, pid: Pid);
-    /// Remove a thread from the ready queue.
-    fn remove(&self, pid: Pid);
     /// Select a thread to run, pop it from the queue.
     fn pop(&self) -> Option<Pid>;
     /// Got a tick from CPU.
diff --git a/crate/thread/src/scheduler/rr.rs b/crate/thread/src/scheduler/rr.rs
index eb79b76..5ff7589 100644
--- a/crate/thread/src/scheduler/rr.rs
+++ b/crate/thread/src/scheduler/rr.rs
@@ -21,9 +21,6 @@ impl Scheduler for RRScheduler {
     fn push(&self, pid: usize) {
         self.inner.lock().push(pid);
     }
-    fn remove(&self, pid: usize) {
-        self.inner.lock().remove(pid);
-    }
     fn pop(&self) -> Option<usize> {
         self.inner.lock().pop()
     }
@@ -59,14 +56,6 @@ impl RRSchedulerInner {
         trace!("rr push {}", pid - 1);
     }
 
-    fn remove(&mut self, pid: Pid) {
-        let pid = pid + 1;
-        assert!(self.infos[pid].present);
-        self.infos[pid].present = false;
-        self._list_remove(pid);
-        trace!("rr remove {}", pid - 1);
-    }
-
     fn pop(&mut self) -> Option<Pid> {
         let ret = match self.infos[0].next {
             0 => None,
diff --git a/crate/thread/src/scheduler/stride.rs b/crate/thread/src/scheduler/stride.rs
index 12292a7..c16fcef 100644
--- a/crate/thread/src/scheduler/stride.rs
+++ b/crate/thread/src/scheduler/stride.rs
@@ -38,9 +38,6 @@ impl Scheduler for StrideScheduler {
     fn push(&self, pid: usize) {
         self.inner.lock().push(pid);
     }
-    fn remove(&self, pid: usize) {
-        self.inner.lock().remove(pid);
-    }
     fn pop(&self) -> Option<usize> {
         self.inner.lock().pop()
     }
@@ -76,24 +73,6 @@ impl StrideSchedulerInner {
         trace!("stride push {}", pid);
     }
 
-    fn remove(&mut self, pid: Pid) {
-        let info = &mut self.infos[pid];
-        assert!(info.present);
-        info.present = false;
-        if self.queue.peek().is_some() && self.queue.peek().unwrap().1 == pid {
-            self.queue.pop();
-        } else {
-            // BinaryHeap only support pop the top.
-            // So in order to remove an arbitrary element,
-            // we have to take all elements into a Vec,
-            // then push the rest back.
-            let rest: Vec<_> = self.queue.drain().filter(|&p| p.1 != pid).collect();
-            use core::iter::FromIterator;
-            self.queue = BinaryHeap::from_iter(rest.into_iter());
-        }
-        trace!("stride remove {}", pid);
-    }
-
     fn pop(&mut self) -> Option<Pid> {
         let ret = self.queue.pop().map(|(_, pid)| pid);
         if let Some(pid) = ret {
diff --git a/crate/thread/src/thread_pool.rs b/crate/thread/src/thread_pool.rs
index 487dc77..6b05b58 100644
--- a/crate/thread/src/thread_pool.rs
+++ b/crate/thread/src/thread_pool.rs
@@ -135,7 +135,7 @@ impl ThreadPool {
         trace!("process {} {:?} -> {:?}", tid, proc.status, status);
         match (&proc.status, &status) {
             (Status::Ready, Status::Ready) => return,
-            (Status::Ready, _) => self.scheduler.remove(tid),
+            (Status::Ready, _) => panic!("can not remove a process from ready queue"),
             (Status::Exited(_), _) => panic!("can not set status for a exited process"),
             (Status::Sleeping, Status::Exited(_)) => self.timer.lock().stop(Event::Wakeup(tid)),
             (_, Status::Ready) => self.scheduler.push(tid),