Practical Tips: Linux time delay and operation Delay

Article Title: Practical Tips: Time Delay and operation delay in Linux. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source. 1. The timer header function in the kernel is # include

2. The Hz symbol indicates the number of tick answers generated per second, that is, the interruption of time generated in one second.

3. # include

Volatile unsigned long jiffies uses this variable to measure time changes.

4. int time_after (unsigned long a, unsigned long B)

Int time_before (unsigned long a, unsigned long B)

These boolean expressions compare the value of jiffies in a safe way, so you do not need to consider the problem of timer overflow.

5. The value conversion between the time represented by jiffies and other representation methods:

unsigned long timespec_to_jiffies(struct timespec *value);void jiffies_to_timespec(unsigned long jiffies, struct timespec *value);unsigned long timeval_to_jiffies(struct timeval *value);void jiffies_to_timeval(unsigned long jiffies, struct timeval *value);

(I can't remember each time. I wrote it to my blog for future use.) timespec and timeval are the clock time structures in linux:

struct timeval { time_t tv_sec; /* seconds */ suseconds_t tv_usec; /* microseconds */ };struct timespec { long int tv_sec; long int tv_nsec; };

Header files using this structure are in # include. The common functions are:

int gettimeofday(struct timeval *tv, struct timezone *tz);