Print the module load time in Linux Device Driver while unloading

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In Linux Kernel, the number of timer interrupts per second is defined by 'HZ' variable.

You can get the value of HZ Variable by running the following command.

grep 'CONFIG_HZ=' /boot/config-$(uname -r)

For example, if the value is 250, it means there will be 250 timer interrupts per second.

Linux kernel maintains a global variable 'jiffies' which will be incremented for every timer interrupt. So, for every second, it will be incremented by HZ.

Header File: #include <linux/jiffies.h>

extern unsigned long volatile jiffies;

HZ = (number of ticks)/sec

jiffies = number of ticks

To convert from seconds to unit jiffies: HZ * jiffies

Convert from jiffies to seconds: jiffies/HZ

Code to measure the Driver Load Time:


Output:



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