linux-kernel - Re: Subject: [PATCH] [PATCH] time: tick-sched: use bool for tick

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Date:   Tue, 10 Apr 2018 16:15:04 +0800
From:   yuankuiz@...eaurora.org
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        aulmck@...ux.vnet.ibm.com, Ingo Molnar <mingo@...nel.org>,
        Len Brown <len.brown@...el.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-pm-owner@...r.kernel.org
Subject: Re: Subject: [PATCH] [PATCH] time: tick-sched: use bool for
 tick_stopped

On 2018-04-10 04:00 PM, Rafael J. Wysocki wrote:
> On Tue, Apr 10, 2018 at 9:33 AM,  <yuankuiz@...eaurora.org> wrote:
>> From: John Zhao <yuankuiz@...eaurora.org>
>> 
>> Variable tick_stopped returned by tick_nohz_tick_stopped
>> can have only true / forse 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 int.
>> Moreover, the executed instructions cost could be minimal
>> without potiential data type conversion.
>> 
>> Signed-off-by: John Zhao <yuankuiz@...eaurora.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".

> 
> Thanks!