Given the description below, jiffies + 10*HZ means (now + 10 Seconds). And jiffies * 1000 would mean the elapsed time in milliseconds etc.
An example of usage in the Linux Kernel would be in the drivers for XD, where, jiffies + 8*HZ later (as initialized in the member element expires of static struct timer_list) a timer interrupt handler is programmed to execute.
The “watchdog handler” xd_watchdog, in this particular instance, wakes up a sleeping process.
Needless to say, all appropriate caveats emptor apply. Appropriate Processes need to have been sleeping, Timers must have been declared and initialized etc etc
I will blog on this at length later. Please subscribe to our mail list for automated updates on new blog entries.
I explain this specific Linux Kernel concept and more in my classes ( Advanced Linux Kernel Programming @UCSC-Extension, and also in other classes that I teach independently). As always, Feedback, Questions and Comments are appreciated and will be responded to.