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

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Message-ID: <2c7c90722795ecfbe4e3e907f725549c@codeaurora.org>
Date:   Wed, 25 Apr 2018 15:01:46 +0800
From:   yuankuiz@...eaurora.org
To:     Joe Perches <joe@...ches.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        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, akpm@...ux-foundation.org
Subject: Re: [PATCH] time: tick-sched: use bool for tick_stopped

On 2018-04-21 03:24 AM, Joe Perches wrote:
> On Fri, 2018-04-20 at 14:44 +0800, yuankuiz@...eaurora.org wrote:
>> On 2018-04-20 09:47 AM, yuankuiz@...eaurora.org wrote:
> []
>> > [ZJ] Further prototyping has been given based on gcc for both of
>> > x86_64 and armv8-a,
>> >      unsigned int and bool share the same 1 bytes without the
>> > addtional storage for sure.
>> >      Open this and welcome if any other difference behaviour could be
>> > captured.
>> 
>> [ZJ] Typo.. change 4 bytes above to 1 byte actually.
> 
> Not really.
> 
> unsigned int is 4 and bool is generally 1.
> Alignment padding after a bool may exist.
[ZJ] Depending on how to pack, the size was padded is variance. For 
example.
      In case of the "unsigned char" at the following, pack is happened 
and result 1 bytes.(if no more than 8 bits are used)
      In case of the "int" at the following, pack is happened but result 
4 bytes.
      I mean, I demo it but use the 1# case due for another thread 
discussion on the ichx_desc() so move a little bit from the tick_sched 
struct.