Re: Jiffies Wraparound (was Re: interrupt counts)

Ingo Molnar (
Tue, 20 Aug 1996 11:12:53 +0200 (MET DST)

On 20 Aug 1996, Thomas Koenig wrote:

> In, Linus Torvalds <torvalds@cs.Helsinki.FI> wrote:
> >In _many_ places we do the jiffies handling correctly. Not in every place,
> >though (or even most places).
> What about adding an option 'Test jiffie wraparound' to the
> 'kernel hacking' section of the configuration? This could be used
> to set that jiffies wrap around (configurable via a boot option,
> for example). I'm sure there are people who would like to try this
> out :-)

I've tested it once by setting jiffies to 0xFFFFF000 in main.c, and
nothing bad happened. Some of the hardware timeouts are handled by using
absolute jiffies values and comparing them with <, but these timers are
usually for error detection. Important timings are done with kernel
timers, and they are wraparound-insensitive :)

And who needs timers with more than 400 days timeout :) [well ...]

-- mingo