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    SubjectRe: [PATCH] time: tick-sched: use bool for tick_stopped
    Hi Thomas,

    On 2018-04-10 05:10 PM, Thomas Gleixner wrote:
    > On Tue, 10 Apr 2018, yuankuiz@codeaurora.org wrote:
    >> On 2018-04-10 04:00 PM, Rafael J. Wysocki wrote:
    >> > On Tue, Apr 10, 2018 at 9:33 AM, <yuankuiz@codeaurora.org> wrote:
    >> > > From: John Zhao <yuankuiz@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 <yuankuiz@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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