diff --git a/kernel/aster-nix/src/syscall/alarm.rs b/kernel/aster-nix/src/syscall/alarm.rs
index f6a66fe03..f1cc6e29c 100644
--- a/kernel/aster-nix/src/syscall/alarm.rs
+++ b/kernel/aster-nix/src/syscall/alarm.rs
@@ -3,13 +3,13 @@
 use core::time::Duration;
 
 use super::SyscallReturn;
-use crate::prelude::*;
+use crate::{prelude::*, time::timer::Timeout};
 
 pub fn sys_alarm(seconds: u32) -> Result<SyscallReturn> {
     debug!("seconds = {}", seconds);
 
     let current = current!();
-    let alarm_timer = current.alarm_timer();
+    let alarm_timer = current.timer_manager().alarm_timer();
 
     let remaining = alarm_timer.remain();
     let mut remaining_secs = remaining.as_secs();
@@ -23,7 +23,7 @@ pub fn sys_alarm(seconds: u32) -> Result<SyscallReturn> {
         return Ok(SyscallReturn::Return(remaining_secs as _));
     }
 
-    alarm_timer.set_timeout(Duration::from_secs(seconds as u64));
+    alarm_timer.set_timeout(Timeout::After(Duration::from_secs(seconds as u64)));
 
     Ok(SyscallReturn::Return(remaining_secs as _))
 }
diff --git a/kernel/aster-nix/src/time/core/timer.rs b/kernel/aster-nix/src/time/core/timer.rs
index 5334cf4f1..bb191491c 100644
--- a/kernel/aster-nix/src/time/core/timer.rs
+++ b/kernel/aster-nix/src/time/core/timer.rs
@@ -15,6 +15,14 @@ use aster_frame::sync::SpinLock;
 
 use super::Clock;
 
+/// A timeout, represented in one of the two ways.
+pub enum Timeout {
+    /// The timeout is reached _after_ the `Duration` time is elapsed.
+    After(Duration),
+    /// The timeout is reached _when_ the clock's time is equal to `Duration`.
+    When(Duration),
+}
+
 /// A timer with periodic functionality.
 ///
 /// Setting the timer will trigger a callback function upon expiration of
@@ -65,9 +73,15 @@ impl Timer {
     /// The registered callback function of this timer will be invoked
     /// when reaching timeout. If the timer has a valid interval, this timer
     /// will be set again with the interval when reaching timeout.
-    pub fn set_timeout(self: &Arc<Self>, timeout: Duration) {
-        let now = self.timer_manager.clock.read_time();
-        let expired_time = now + timeout;
+    pub fn set_timeout(self: &Arc<Self>, timeout: Timeout) {
+        let expired_time = match timeout {
+            Timeout::After(timeout) => {
+                let now = self.timer_manager.clock.read_time();
+                now + timeout
+            }
+            Timeout::When(timeout) => timeout,
+        };
+
         let timer_weak = Arc::downgrade(self);
         let new_timer_callback = Arc::new(TimerCallback::new(
             expired_time,
@@ -107,6 +121,11 @@ impl Timer {
     pub fn timer_manager(&self) -> &Arc<TimerManager> {
         &self.timer_manager
     }
+
+    /// Returns the interval time of the current timer.
+    pub fn interval(&self) -> Duration {
+        *self.interval.lock_irq_disabled()
+    }
 }
 
 fn interval_timer_callback(timer: &Weak<Timer>) {
@@ -117,7 +136,7 @@ fn interval_timer_callback(timer: &Weak<Timer>) {
     (timer.registered_callback)();
     let interval = timer.interval.lock_irq_disabled();
     if *interval != Duration::ZERO {
-        timer.set_timeout(*interval);
+        timer.set_timeout(Timeout::After(*interval));
     }
 }
 
diff --git a/kernel/aster-nix/src/time/wait.rs b/kernel/aster-nix/src/time/wait.rs
index efd5c56dd..b8c920a06 100644
--- a/kernel/aster-nix/src/time/wait.rs
+++ b/kernel/aster-nix/src/time/wait.rs
@@ -4,7 +4,7 @@ use core::time::Duration;
 
 use aster_frame::sync::{WaitQueue, Waiter};
 
-use super::clocks::JIFFIES_TIMER_MANAGER;
+use super::{clocks::JIFFIES_TIMER_MANAGER, timer::Timeout};
 
 /// A trait that provide the timeout related function for [`WaitQueue`]`.
 pub trait WaitTimeout {
@@ -34,7 +34,7 @@ impl WaitTimeout for WaitQueue {
         let jiffies_timer = JIFFIES_TIMER_MANAGER.get().unwrap().create_timer(move || {
             waker.wake_up();
         });
-        jiffies_timer.set_timeout(*timeout);
+        jiffies_timer.set_timeout(Timeout::After(*timeout));
 
         let cancel_cond = {
             let jiffies_timer = jiffies_timer.clone();
diff --git a/kernel/aster-nix/src/vdso.rs b/kernel/aster-nix/src/vdso.rs
index b2822973a..a9eaa0943 100644
--- a/kernel/aster-nix/src/vdso.rs
+++ b/kernel/aster-nix/src/vdso.rs
@@ -26,8 +26,8 @@ use spin::Once;
 
 use crate::{
     fs::fs_resolver::{FsPath, FsResolver, AT_FDCWD},
-    syscall::ClockID,
-    time::{clocks::MonotonicClock, SystemTime, START_TIME},
+    syscall::ClockId,
+    time::{clocks::MonotonicClock, timer::Timeout, SystemTime, START_TIME},
     vm::vmo::{Vmo, VmoOptions},
 };
 
@@ -49,12 +49,12 @@ enum VdsoClockMode {
 
 /// Instant used in `VdsoData`.
 ///
-/// Each `VdsoInstant` will store a instant information for a specified `ClockID`.
+/// Each `VdsoInstant` will store a instant information for a specified `ClockId`.
 /// The `secs` field will record the seconds of the instant,
 /// and the `nanos_info` will store the nanoseconds of the instant
 /// (for `CLOCK_REALTIME_COARSE` and `CLOCK_MONOTONIC_COARSE`) or
 /// the calculation results of left-shift `nanos` with `lshift`
-/// (for other high-resolution `ClockID`s).
+/// (for other high-resolution `ClockId`s).
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, Pod)]
 struct VdsoInstant {
@@ -100,16 +100,16 @@ struct VdsoData {
     arch_data: ArchVdsoData,
 }
 
-const HIGH_RES_CLOCK_IDS: [ClockID; 4] = [
-    ClockID::CLOCK_REALTIME,
-    ClockID::CLOCK_MONOTONIC,
-    ClockID::CLOCK_MONOTONIC_RAW,
-    ClockID::CLOCK_BOOTTIME,
+const HIGH_RES_CLOCK_IDS: [ClockId; 4] = [
+    ClockId::CLOCK_REALTIME,
+    ClockId::CLOCK_MONOTONIC,
+    ClockId::CLOCK_MONOTONIC_RAW,
+    ClockId::CLOCK_BOOTTIME,
 ];
 
-const COARSE_RES_CLOCK_IDS: [ClockID; 2] = [
-    ClockID::CLOCK_REALTIME_COARSE,
-    ClockID::CLOCK_MONOTONIC_COARSE,
+const COARSE_RES_CLOCK_IDS: [ClockId; 2] = [
+    ClockId::CLOCK_REALTIME_COARSE,
+    ClockId::CLOCK_MONOTONIC_COARSE,
 ];
 
 impl VdsoData {
@@ -159,7 +159,7 @@ impl VdsoData {
     fn update_high_res_instant(&mut self, instant: Instant, instant_cycles: u64) {
         self.last_cycles = instant_cycles;
         for clock_id in HIGH_RES_CLOCK_IDS {
-            let secs = if clock_id == ClockID::CLOCK_REALTIME {
+            let secs = if clock_id == ClockId::CLOCK_REALTIME {
                 instant.secs() + START_SECS_COUNT.get().unwrap()
             } else {
                 instant.secs()
@@ -175,7 +175,7 @@ impl VdsoData {
 
     fn update_coarse_res_instant(&mut self, instant: Instant) {
         for clock_id in COARSE_RES_CLOCK_IDS {
-            let secs = if clock_id == ClockID::CLOCK_REALTIME_COARSE {
+            let secs = if clock_id == ClockId::CLOCK_REALTIME_COARSE {
                 instant.secs() + START_SECS_COUNT.get().unwrap()
             } else {
                 instant.secs()
@@ -269,7 +269,7 @@ impl Vdso {
     }
 
     /// Update the requisite fields of the VDSO data in the `data_frame`.
-    fn update_data_frame_instant(&self, clockid: ClockID) {
+    fn update_data_frame_instant(&self, clockid: ClockId) {
         let clock_index = clockid as usize;
         let secs_offset = 0xA0 + clock_index * 0x10;
         let nanos_info_offset = 0xA8 + clock_index * 0x10;
@@ -323,7 +323,7 @@ pub(super) fn init() {
         MonotonicClock::timer_manager().create_timer(update_vdso_coarse_res_instant),
     );
     coarse_instant_timer.set_interval(Duration::from_millis(100));
-    coarse_instant_timer.set_timeout(Duration::from_millis(100));
+    coarse_instant_timer.set_timeout(Timeout::After(Duration::from_millis(100)));
 }
 
 /// Return the VDSO vmo.