hrtimer核心高精度定時器
阿新 • • 發佈：2019-01-07
#include <linux/kernel.h> #include <linux/module.h> #include <linux/hrtimer.h> #include <linux/ktime.h> MODULE_LICENSE("GPL"); static struct hrtimer hr_timer; static struct work_struct wq_hrtimer; static ktime_t ktime; static unsigned int interval=5000; /* unit: us */ struct timespec uptimeLast; static unsigned int count=0; #define COUNT_INTERVAL 4000 unsigned long long diff_tv(struct timespec start, struct timespec end) { return (end.tv_sec-start.tv_sec)*1000000000+(end.tv_nsec-start.tv_nsec); } enum hrtimer_restart my_hrtimer_callback( struct hrtimer *timer ) { schedule_work(&wq_hrtimer); return HRTIMER_NORESTART; } static void wq_func_hrtimer(struct work_struct *work) { struct timespec uptime; hr_timer.function = my_hrtimer_callback; ktime = ktime_set( interval/1000000, (interval%1000000)*1000 ); hrtimer_start(&hr_timer, ktime, HRTIMER_MODE_REL ); /* print time every COUNT_INTERVAL*interval second*/ if(count%COUNT_INTERVAL==0) { do_posix_clock_monotonic_gettime(&uptime); printk(KERN_INFO"hrtimer:%9lu sec, %9lu ns, interval_delay=%lu ns\n", (unsigned long) uptime.tv_sec, uptime.tv_nsec, (unsigned long)(diff_tv(uptimeLast, uptime)-interval*1000*COUNT_INTERVAL) \ /COUNT_INTERVAL); uptimeLast=uptime; } count++; } static int __init module_hrtimer_init( void ) { struct timespec uptime; printk(KERN_INFO"HR Timer module installing\n"); hrtimer_init( &hr_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL ); ktime = ktime_set( interval/1000000, (interval%1000000)*1000 ); hr_timer.function = my_hrtimer_callback; hrtimer_start( &hr_timer, ktime, HRTIMER_MODE_REL ); do_posix_clock_monotonic_gettime(&uptime); uptimeLast = uptime; printk(KERN_INFO"hrtimer:%9lu sec, %9lu ns\n", (unsigned long) uptime.tv_sec, uptime.tv_nsec ); INIT_WORK(&wq_hrtimer, wq_func_hrtimer); return 0; } static void __exit module_hrtimer_exit( void ) { int ret; ret = hrtimer_cancel( &hr_timer ); if (ret) printk("The timer was still in use...\n"); printk("HR Timer module uninstalling\n"); return; } module_init(module_hrtimer_init); module_exit(module_hrtimer_exit);