I understand what jiffies are and how to get the values in linux but I don't understand the purpose of it and how this value could be used ? Why do we even need it in the first place ? Could someone please explain to me ?

Thanks,

CodePudding user response：

By and large, you don't need to use jiffies. They're an implementation detail of how the Linux kernel keeps track of time, and somewhat obsolete at that. Quoting man 7 time:

The software clock, HZ, and jiffies

The accuracy of various system calls that set timeouts, (e.g., select(2), sigtimedwait(2)) and measure CPU time (e.g., getrusage(2)) is limited by the resolution of the software clock, a clock maintained by the kernel which measures time in jiffies. The size of a jiffy is determined by the value of the kernel constant HZ.

...

High-resolution timers

Since Linux 2.6.21, Linux supports high-resolution timers (HRTs), optionally configurable via CONFIG_HIGH_RES_TIMERS. On a system that supports HRTs, the accuracy of sleep and timer system calls is no longer constrained by the jiffy, but instead can be as accurate as the hardware allows (microsecond accuracy is typical of modern hardware).

Instead of using jiffies, just use the higher-level calls like gettimeofday(2) which work in more standardized units like seconds.