Re: [PATCH v2] sched/uclamp: Fix overzealous type replacement

[Vincent Guittot]

On Fri, 15 Nov 2019 at 18:10, Valentin Schneider
<valentin.schneider@xxxxxxx> wrote:
>
> On 15/11/2019 14:29, Valentin Schneider wrote:
> > On 15/11/2019 14:07, Vincent Guittot wrote:
> >>> -static inline enum uclamp_id uclamp_none(enum uclamp_id clamp_id)
> >>> +static inline unsigned int uclamp_none(enum uclamp_id clamp_id)
> >>
> >> Out of curiosity why uclamp decided to use unsigned int to manipulate
> >> utilization instead of unsigned long which is the type of util_avg ?
> >>
> >
> > I didn't stare at the discussion much, but I think it stems from the
> > design choices behind struct uclamp_se: everything is crammed in an unsigned
> > int bitfield. Let me see if I can find some relevant mails.
> >
>
> So I think a relevant mail is:
>
> https://lore.kernel.org/lkml/20180912174236.GB24106@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
>
> Other than that, the uclamp_se.value field was 'int' in v1 and has been
> 'unsigned int' for all following versions. uclamp_bucket.value is a bitfield
> of an 'unsigned long' just because we want more headroom for the tasks count,
> AFAICT.

Thanks for the pointer and deep diving in the email threads