Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle period

[Peter Zijlstra]

On Wed, Jan 20, 2016 at 12:46:48PM -0500, Nicolas Pitre wrote:
> > +struct stats {
> > +   u64           sum;                     /* sum of values */
> > +   u32           values[STATS_NR_VALUES]; /* array of values */
> > +   unsigned char w_ptr;                   /* current window pointer */
> 
> Why did you change this from an unsigned int?
> 
> This won't provide any memory space saving given that the structure has 
> to be padded up to the next 64-bit boundary.

Not to mention that loading bytes is more expensive on many archs
compared to full words.

Also, its not a pointer, its an index.

So:     unsigned int w_idx;