kernel获取毫秒、微妙时间

最新推荐文章于 2025-01-03 18:57:43 发布

lostnx

最新推荐文章于 2025-01-03 18:57:43 发布

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分类专栏： rk3328 kernel C 文章标签：毫秒微妙延时

本文链接：https://blog.youkuaiyun.com/wolfnx/article/details/101324303

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本文介绍在Linux内核环境下两种获取精确时间的方法，并通过具体测试案例对比了毫秒级、微秒级和纳秒级的时间测量效果，推荐使用do_gettimeofday进行高精度计时。

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Kernel: v4.4.159
Device: rk3328
Platform Version: Android 9.0

前言：

有时需要在kernel中测试一个函数或者语句的执行时间，就要获取精确的毫秒、微妙的值。下面记录一下两种获取时间的方法及测试结果:

方式1：(推荐使用)

#include <linux/time.h> //需要包含的头文件
struct timeval tstart;  //结构体
do_gettimeofday(&tstart);//获取时间
//打印秒、微妙值
printk("%s, stime: %lds, utime: %ldus\n"\
		, __func__, tstart.tv_sec, tstart.tv_usec);

方式2：(经测试时间未变，不适用于此场景)

#include <linux/time.h>//需要包含的文件
struct timespec time0 = current_kernel_time();//获取时间
//打印秒、纳秒值
printk("%s, stime: %lds, ntime: %ldns\n",\
			 __func__, time0.tv_sec, time0.tv_nsec);

测试方式1

void test1(void)
{
	struct timeval tstart, tend;
	printk("----------------------------------------------------\n");
	do_gettimeofday(&tstart);
	printk("%s, stime: %lds, utime: %ldus\n", __func__, tstart.tv_sec, tstart.tv_usec);
	printk("%s, before mtime: %ldms\n", __func__, 1000 * tstart.tv_sec + tstart.tv_usec / 1000);
	mdelay(1);//延时1ms
	do_gettimeofday(&tend);
	printk("%s, stime: %lds, utime: %ldus\n", __func__, tend.tv_sec, tend.tv_usec);
	printk("%s, after mtime: %ldms\n", __func__, 1000 * tend.tv_sec + tend.tv_usec / 1000);
	printk("%s, time taken: %ldms\n", __func__, 1000 * (tend.tv_sec - tstart.tv_sec) + (tend.tv_usec - tstart.tv_usec) / 1000);
}

void test2(void)
{
	struct timeval tstart, tend;
	printk("----------------------------------------------------\n");
	do_gettimeofday(&tstart);
	printk("%s, stime: %lds, utime: %ldus\n", __func__, tstart.tv_sec, tstart.tv_usec);
	printk("%s, before mtime: %ldus\n", __func__, 1000 * 1000 * tstart.tv_sec + tstart.tv_usec);
	udelay(1);//延时1us
	do_gettimeofday(&tend);
	printk("%s, stime: %lds, utime: %ldus\n", __func__, tend.tv_sec, tend.tv_usec);
	printk("%s, after mtime: %ldus\n", __func__, 1000 * 1000 * tend.tv_sec + tend.tv_usec);
	printk("%s, time taken: %ldus\n", __func__, 1000 * 1000 * (tend.tv_sec - tstart.tv_sec) + (tend.tv_usec - tstart.tv_usec));
}

测试方式2

void test3(void)
{
	struct timespec time0, time1;
	printk("----------------------------------------------------\n");
	time0 = current_kernel_time();
	printk("%s, before stime: %lds, ntime: %ldns\n", __func__, time0.tv_sec, time0.tv_nsec);
	mdelay(1);//延时1ms
	time1 = current_kernel_time();
	printk("%s, after stime: %lds, ntime: %ldns\n", __func__, time1.tv_sec, time1.tv_nsec);
	printk("%s, ntime taken: %ldns\n", __func__, time1.tv_nsec - time0.tv_nsec);
}

void test4(void)
{
	struct timespec time0, time1;
	printk("----------------------------------------------------\n");
	time0 = current_kernel_time();
	printk("%s, before stime: %lds, ntime: %ldns\n", __func__, time0.tv_sec, time0.tv_nsec);
	udelay(1);//延时1us
	time1 = current_kernel_time();
	printk("%s, after stime: %lds, ntime: %ldns\n", __func__, time1.tv_sec, time1.tv_nsec);
	printk("%s, ntime taken: %ldns\n", __func__, time1.tv_nsec - time0.tv_nsec);
}

void test5(void)
{
	struct timespec time0, time1;
	printk("----------------------------------------------------\n");
	time0 = current_kernel_time();
	printk("%s, before stime: %lds, ntime: %ldns\n", __func__, time0.tv_sec, time0.tv_nsec);
	ndelay(1);//延时1ns
	time1 = current_kernel_time();
	printk("%s, after stime: %lds, ntime: %ldns\n", __func__, time1.tv_sec, time1.tv_nsec);
	printk("%s, ntime taken: %ldns\n", __func__, time1.tv_nsec - time0.tv_nsec);
}