diff --git a/os/src/task/id.rs b/os/src/task/id.rs
index cfb50367..4eec31ed 100644
--- a/os/src/task/id.rs
+++ b/os/src/task/id.rs
@@ -157,7 +157,7 @@ impl TaskUserRes {
         let process = self.process.upgrade().unwrap();
         let mut process_inner = process.inner_exclusive_access();
         // alloc user stack
-        kprintln!("[KERN] task::id::TaskUserRes::alloc_user_res(): alloc user stack");
+        kprintln!("[KERN] task::id::TaskUserRes::alloc_user_res(): alloc user stack for TCB");
         let ustack_bottom = ustack_bottom_from_tid(self.ustack_base, self.tid);
         let ustack_top = ustack_bottom + USER_STACK_SIZE;
         process_inner.memory_set.insert_framed_area(
@@ -166,7 +166,7 @@ impl TaskUserRes {
             MapPermission::R | MapPermission::W | MapPermission::U,
         );
         // alloc trap_cx
-        kprintln!("[KERN] task::id::TaskUserRes::alloc_user_res(): alloc trap_cx");
+        kprintln!("[KERN] task::id::TaskUserRes::alloc_user_res(): alloc trap_cx for TCB");
         let trap_cx_bottom = trap_cx_bottom_from_tid(self.tid);
         let trap_cx_top = trap_cx_bottom + PAGE_SIZE;
         process_inner.memory_set.insert_framed_area(
diff --git a/os/src/task/process.rs b/os/src/task/process.rs
index c881c59a..08ca3104 100644
--- a/os/src/task/process.rs
+++ b/os/src/task/process.rs
@@ -134,9 +134,10 @@ impl ProcessControlBlock {
         let mut process_inner = process.inner_exclusive_access();
         process_inner.tasks.push(Some(Arc::clone(&task)));
         drop(process_inner);
+        kprintln!("[KERN] task::process::new(): insert <pid, PCB> in PID2PCB BTreeMap");
         insert_into_pid2process(process.getpid(), Arc::clone(&process));
         // add main thread to scheduler
-        kprintln!("[KERN] task::process::new(): add_task(task): add main thread to tscheduler");
+        kprintln!("[KERN] task::process::new(): add_task(task): add main thread to scheduler");
         add_task(task);
         kprintln!("[KERN] task::process::new() end");
         process
@@ -203,10 +204,13 @@ impl ProcessControlBlock {
         let mut parent = self.inner_exclusive_access();
         assert_eq!(parent.thread_count(), 1);
         // clone parent's memory_set completely including trampoline/ustacks/trap_cxs
+        kprintln!("[KERN] task::process::fork(): clone parent's memory_set for child");
         let memory_set = MemorySet::from_existed_user(&parent.memory_set);
         // alloc a pid
+        kprintln!("[KERN] task::process::fork(): alloc a new pid for child");
         let pid = pid_alloc();
         // copy fd table
+        kprintln!("[KERN] task::process::fork(): copy fd table for child");
         let mut new_fd_table: Vec<Option<Arc<dyn File + Send + Sync>>> = Vec::new();
         for fd in parent.fd_table.iter() {
             if let Some(file) = fd {
@@ -216,6 +220,7 @@ impl ProcessControlBlock {
             }
         }
         // create child process pcb
+        kprintln!("[KERN] task::process::fork(): new child PCB with new pid, memory_set, fd_table, ...");
         let child = Arc::new(Self {
             pid,
             inner: unsafe {
@@ -236,8 +241,10 @@ impl ProcessControlBlock {
             },
         });
         // add child
+        kprintln!("[KERN] task::process::fork(): add child link in parent' children Vec");
         parent.children.push(Arc::clone(&child));
         // create main thread of child process
+        kprintln!("[KERN] task::process::fork(): TaskControlBlock::new(): create main thread of child process");
         let task = Arc::new(TaskControlBlock::new(
             Arc::clone(&child),
             parent
@@ -252,16 +259,20 @@ impl ProcessControlBlock {
             false,
         ));
         // attach task to child process
+        kprintln!("[KERN] task::process::fork(): attach child TCB to child PCB");
         let mut child_inner = child.inner_exclusive_access();
         child_inner.tasks.push(Some(Arc::clone(&task)));
         drop(child_inner);
         // modify kstack_top in trap_cx of this thread
+        kprintln!("[KERN] task::process::fork(): modify child's kstack_top in trap_cx of child");
         let task_inner = task.inner_exclusive_access();
         let trap_cx = task_inner.get_trap_cx();
         trap_cx.kernel_sp = task.kstack.get_top();
         drop(task_inner);
+        kprintln!("[KERN] task::process::fork(): insert <child pid, child PCB> in PID2PCB BTreeMap");
         insert_into_pid2process(child.getpid(), Arc::clone(&child));
         // add this thread to scheduler
+        kprintln!("[KERN] task::process::fork(): add_task(child task): add child thread to scheduler");
         add_task(task);
         kprintln!("[KERN] task::process::fork() end");
         child
diff --git a/os/src/task/task.rs b/os/src/task/task.rs
index 07127bd4..b01f68bf 100644
--- a/os/src/task/task.rs
+++ b/os/src/task/task.rs
@@ -52,6 +52,7 @@ impl TaskControlBlock {
         kprintln!("[KERN] TaskControlBlock::new() begin");
         let res = TaskUserRes::new(Arc::clone(&process), ustack_base, alloc_user_res);
         let trap_cx_ppn = res.trap_cx_ppn();
+        kprintln!("[KERN] TaskControlBlock::new(): alloc kernel stack for TCB");
         let kstack = kstack_alloc();
         let kstack_top = kstack.get_top();
         kprintln!("[KERN] TaskControlBlock::new() end");