Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

The global variable jiffies holds the number of ticks that have occurred since the system booted. On boot, the kernel initializes the variable to zero, and it is incremented by one during each timer interrupt.

But how the kernel updates this value after waking up from suspend?

How the kernel calculates the time that it had conducted in suspend mode?

share|improve this question
AFAIK It doesn't as during the suspend the timer wasn't interrupted. – Ulrich Dangel Feb 21 '13 at 8:32
It seems to me I found answer: see tick_do_update_jiffies64() which defined in tick-sched.c – ymn Feb 21 '13 at 8:43

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.