diff --git a/ch5/user/src/bin/02sleep.rs b/ch5/user/src/bin/02sleep.rs
index 15bafda..ebba65a 100644
--- a/ch5/user/src/bin/02sleep.rs
+++ b/ch5/user/src/bin/02sleep.rs
@@ -1,6 +1,9 @@
 #![no_std]
 #![no_main]
 
+extern crate alloc;
+
+use alloc::vec::Vec;
 use user_lib::*;
 use user_lib::syscall::*;
 
diff --git a/ch5/user/src/bin/forktest_simple.rs b/ch5/user/src/bin/forktest_simple.rs
new file mode 100644
index 0000000..e086549
--- /dev/null
+++ b/ch5/user/src/bin/forktest_simple.rs
@@ -0,0 +1,29 @@
+#![no_std]
+#![no_main]
+
+
+
+use user_lib::*;
+use syscall::{sys_fork, };
+use user_lib::syscall::sys_getpid;
+
+#[no_mangle]
+pub fn main() -> i32 {
+    assert_eq!(wait(&mut 0i32), -1);
+    println!("sys_wait without child process test passed!");
+    println!("parent start, pid = {}!", sys_getpid());
+    let pid = sys_fork();
+    if pid == 0 {
+        // child process
+        println!("hello child process!");
+        100
+    } else {
+        // parent process
+        let mut exit_code: i32 = 0;
+        println!("ready waiting on parent process!");
+        assert_eq!(pid, wait(&mut exit_code));
+        assert_eq!(exit_code, 100);
+        println!("child process pid = {}, exit code = {}", pid, exit_code);
+        0
+    }
+}
diff --git a/ch5/user/src/bin/forktree.rs b/ch5/user/src/bin/forktree.rs
new file mode 100644
index 0000000..c056646
--- /dev/null
+++ b/ch5/user/src/bin/forktree.rs
@@ -0,0 +1,36 @@
+#![no_std]
+#![no_main]
+
+use user_lib::*;
+use syscall::{sys_fork, sys_getpid, sys_yield};
+use user_lib::syscall::sys_exit;
+
+const DEPTH: usize = 4;
+
+fn fork_child(cur: &str, branch: char) {
+    let mut next = [0u8; DEPTH + 1];
+    let l = cur.len();
+    if l >= DEPTH {
+        return;
+    }
+    next[..l].copy_from_slice(cur.as_bytes());
+    next[l] = branch as u8;
+    if sys_fork() == 0 {
+        fork_tree(core::str::from_utf8(&next[..l + 1]).unwrap());
+        sys_yield();
+        sys_exit(0);
+    }
+}
+
+fn fork_tree(cur: &str) {
+    println!("pid{}: {}", sys_getpid(), cur);
+    fork_child(cur, '0');
+    fork_child(cur, '1');
+}
+
+#[no_mangle]
+pub fn main() -> i32 {
+    fork_tree("");
+    sleep(3000);
+    0
+}
diff --git a/ch5/user/src/bin/matrix.rs b/ch5/user/src/bin/matrix.rs
new file mode 100644
index 0000000..cbb5e6e
--- /dev/null
+++ b/ch5/user/src/bin/matrix.rs
@@ -0,0 +1,70 @@
+#![no_std]
+#![no_main]
+#![allow(clippy::needless_range_loop)]
+
+use user_lib::*;
+use syscall::{sys_fork, sys_getpid, sys_yield};
+use user_lib::syscall::{sys_exit, sys_get_time};
+
+
+static NUM: usize = 30;
+const N: usize = 10;
+static P: i32 = 10007;
+type Arr = [[i32; N]; N];
+
+fn work(times: isize) {
+    let mut a: Arr = Default::default();
+    let mut b: Arr = Default::default();
+    let mut c: Arr = Default::default();
+    for i in 0..N {
+        for j in 0..N {
+            a[i][j] = 1;
+            b[i][j] = 1;
+        }
+    }
+    sys_yield();
+    println!("pid {} is running ({} times)!.", sys_getpid(), times);
+    for _ in 0..times {
+        for i in 0..N {
+            for j in 0..N {
+                c[i][j] = 0;
+                #[allow(clippy::needless_range_loop)]
+                for k in 0..N {
+                    c[i][j] = (c[i][j] + a[i][k] * b[k][j]) % P;
+                }
+            }
+        }
+        for i in 0..N {
+            for j in 0..N {
+                a[i][j] = c[i][j];
+                b[i][j] = c[i][j];
+            }
+        }
+    }
+    println!("pid {} done!.", sys_getpid());
+    sys_exit(0);
+}
+
+#[no_mangle]
+pub fn main() -> i32 {
+    for _ in 0..NUM {
+        let pid = sys_fork();
+        if pid == 0 {
+            let current_time = sys_get_time();
+            let times = (current_time as i32 as isize) * (current_time as i32 as isize) % 1000;
+            work(times * 10);
+        }
+    }
+
+    println!("fork ok.");
+
+    let mut exit_code: i32 = 0;
+    for _ in 0..NUM {
+        if wait(&mut exit_code) < 0 {
+            panic!("wait failed.");
+        }
+    }
+    assert!(wait(&mut exit_code) < 0);
+    println!("matrix passed.");
+    0
+}
diff --git a/ch5/user/src/lib.rs b/ch5/user/src/lib.rs
index bf4305a..bacb81b 100644
--- a/ch5/user/src/lib.rs
+++ b/ch5/user/src/lib.rs
@@ -65,3 +65,10 @@ pub fn waitpid(pid: usize, exit_code: &mut i32) -> isize {
         }
     }
 }
+
+pub fn sleep(period_ms: usize) {
+    let start = sys_get_time();
+    while sys_get_time() < start + period_ms as isize {
+        sys_yield();
+    }
+}
\ No newline at end of file