diff --git a/os/Makefile b/os/Makefile
index a9ed0b73..db70d610 100644
--- a/os/Makefile
+++ b/os/Makefile
@@ -77,7 +77,7 @@ ifeq ($(BOARD),qemu)
 		-machine virt \
 		-nographic \
 		-bios $(BOOTLOADER) \
-		-device loader,file=$(KERNEL_BIN),addr=$(KERNEL_ENTRY_PA)
+		-device loader,file=$(KERNEL_BIN),addr=$(KERNEL_ENTRY_PA) -m 1G
 else
 	(which $(K210-BURNER)) || (cd .. && git clone https://github.com/sipeed/kflash.py.git && mv kflash.py tools)
 	@cp $(BOOTLOADER) $(BOOTLOADER).copy
diff --git a/os/src/syscall/mod.rs b/os/src/syscall/mod.rs
index 81ade837..a46eb0f9 100644
--- a/os/src/syscall/mod.rs
+++ b/os/src/syscall/mod.rs
@@ -20,11 +20,11 @@ pub fn syscall(syscall_id: usize, args: [usize; 3]) -> isize {
         SYSCALL_WRITE => sys_write(args[0], args[1] as *const u8, args[2]),
         SYSCALL_EXIT => sys_exit(args[0] as i32),
         SYSCALL_YIELD => sys_yield(),
-        SYSCALL_GET_TIME => sys_get_time(),
         SYSCALL_GETPID => sys_getpid(),
         SYSCALL_FORK => sys_fork(),
         SYSCALL_EXEC => sys_exec(args[0] as *const u8),
         SYSCALL_WAITPID => sys_waitpid(args[0] as isize, args[1] as *mut i32),
+        SYSCALL_GET_TIME => sys_get_time(args[0] as *mut TimeVal, args[1]),
         _ => panic!("Unsupported syscall_id: {}", syscall_id),
     }
 }
diff --git a/os/src/syscall/process.rs b/os/src/syscall/process.rs
index b425d87d..04d1b030 100644
--- a/os/src/syscall/process.rs
+++ b/os/src/syscall/process.rs
@@ -5,13 +5,20 @@ use crate::task::{
     current_user_token,
     add_task,
 };
-use crate::timer::get_time_ms;
 use crate::mm::{
     translated_str,
     translated_refmut,
 };
 use crate::loader::get_app_data_by_name;
 use alloc::sync::Arc;
+use crate::timer::get_time_us;
+
+#[repr(C)]
+#[derive(Debug)]
+pub struct TimeVal {
+    pub sec: usize,
+    pub usec: usize,
+}
 
 pub fn sys_exit(exit_code: i32) -> ! {
     exit_current_and_run_next(exit_code);
@@ -23,10 +30,6 @@ pub fn sys_yield() -> isize {
     0
 }
 
-pub fn sys_get_time() -> isize {
-    get_time_ms() as isize
-}
-
 pub fn sys_getpid() -> isize {
     current_task().unwrap().pid.0 as isize
 }
@@ -94,4 +97,15 @@ pub fn sys_waitpid(pid: isize, exit_code_ptr: *mut i32) -> isize {
         -2
     }
     // ---- release current PCB lock automatically
+}
+
+pub fn sys_get_time(ts: *mut TimeVal, _tz: usize) -> isize {
+    let us = get_time_us();
+    unsafe {
+        *ts = TimeVal {
+            sec: us / 1_000_000,
+            usec: us % 1_000_000,
+        };
+    }
+    0
 }
\ No newline at end of file
diff --git a/os/src/timer.rs b/os/src/timer.rs
index 92d50e3a..7f78d6e4 100644
--- a/os/src/timer.rs
+++ b/os/src/timer.rs
@@ -1,16 +1,16 @@
-use riscv::register::time;
-use crate::sbi::set_timer;
 use crate::config::CLOCK_FREQ;
+use crate::sbi::set_timer;
+use riscv::register::time;
 
 const TICKS_PER_SEC: usize = 100;
-const MSEC_PER_SEC: usize = 1000;
+const MICRO_PER_SEC: usize = 1_000_000;
 
 pub fn get_time() -> usize {
     time::read()
 }
 
-pub fn get_time_ms() -> usize {
-    time::read() / (CLOCK_FREQ / MSEC_PER_SEC)
+pub fn get_time_us() -> usize {
+    time::read() / (CLOCK_FREQ / MICRO_PER_SEC)
 }
 
 pub fn set_next_trigger() {