Re: [PATCH] Provide an interface for getting the current tick length

[Andrew Morton <akpm@osdl.org>]

Paul Mackerras <paulus@samba.org> wrote:
>
> > Can we share that code?
> 
> We could share the code that computes time_adjust_step, i.e. this
> much:
> 
> 	if ((time_adjust_step = time_adjust) != 0) {
> 		/*
> 		 * We are doing an adjtime thing.  Prepare time_adjust_step to
> 		 * be within bounds.  Note that a positive time_adjust means we
> 		 * want the clock to run faster.
> 		 *
> 		 * Limit the amount of the step to be in the range
> 		 * -tickadj .. +tickadj
> 		 */
> 		time_adjust_step = min(time_adjust_step, (long)tickadj);
> 		time_adjust_step = max(time_adjust_step, (long)-tickadj);
> 	}
>

And the next line!

> Is that enough to be worth factoring out?  Note that
> update_wall_time_one_tick() needs both time_adjust_step and
> delta_nsec, so to share more, we would have to have a function
> returning two values and it would start to get ugly.
> 

update_wall_time_one_tick() gets:

	long delta_nsec = new_function();

and your new function becomes

	return (u64)new_function() << (SHIFT_SCALE - 10)) + time_adj;