Hi Thomas,

On 2018-04-10 05:10 PM, Thomas Gleixner wrote:
On Tue, 10 Apr 2018, yuank...@codeaurora.org wrote:
On 2018-04-10 04:00 PM, Rafael J. Wysocki wrote:
> On Tue, Apr 10, 2018 at 9:33 AM,  <yuank...@codeaurora.org> wrote:
> > From: John Zhao <yuank...@codeaurora.org>
> >
> > Variable tick_stopped returned by tick_nohz_tick_stopped
> > can have only true / false values. Since the return type
> > of the tick_nohz_tick_stopped is also bool, variable
> > tick_stopped nice to have data type as bool in place of unsigned int.
> > Moreover, the executed instructions cost could be minimal
> > without potiential data type conversion.
> >
> > Signed-off-by: John Zhao <yuank...@codeaurora.org>
> > ---
> >  kernel/time/tick-sched.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h
> > index 6de959a..4d34309 100644
> > --- a/kernel/time/tick-sched.h
> > +++ b/kernel/time/tick-sched.h
> > @@ -48,8 +48,8 @@ struct tick_sched {
> >         unsigned long                   check_clocks;
> >         enum tick_nohz_mode             nohz_mode;
> >
> > +       bool                            tick_stopped    : 1;
> >         unsigned int                    inidle          : 1;
> > -       unsigned int                    tick_stopped    : 1;
> >         unsigned int                    idle_active     : 1;
> >         unsigned int                    do_timer_last   : 1;
> >         unsigned int                    got_idle_tick   : 1;
>
> I don't think this is a good idea at all.
>
> Please see https://lkml.org/lkml/2017/11/21/384 for example.
[ZJ] Thanks for this sharing. Looks like, this patch fall into the case of
"Maybe".


This patch falls into the case 'pointless' because it adds extra storage
[ZJ] 1 bit vs 1 bit. no more.

for no benefit at all.
[ZJ] tick_stopped is returned by the tick_nohz_tick_stopped() which is bool.
The benefit is no any potiential type conversion could be minded.


Thanks,

        tglx

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