linux-kernel - Re: [PATCH] timer: Use static_branch_likely() for timers_nohz

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Date:   Wed, 23 Jun 2021 18:41:42 +0800
From:   Jisheng Zhang <Jisheng.Zhang@...aptics.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     John Stultz <john.stultz@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] timer: Use static_branch_likely() for
 timers_nohz_active

On Tue, 22 Jun 2021 17:19:20 +0200
Thomas Gleixner <tglx@...utronix.de> wrote:

> 
> 
> On Thu, May 13 2021 at 14:33, Jisheng Zhang wrote:
> > NOHZ is likely to be enabled, so use static_branch_likely() to  
> 
> Why is it likely to be enabled? Did you make a survey of the wider
> distro universe or what?

One more thought: maybe NOHZ is confusing, what I mean here is:
timers_nohz_active is likely to be true.

If I update the commit msg as the following, is it acceptable?

"timers_nohz_active is likely to be true, so use static_branch_likely() to
reflect this fact. This could improve the finally generated code
a bit for the most likely scenario, I.E save two "jmp" instructions."

Thanks

> 
> > reflect this fact. This could improve the finally generated code  
> 
> could improve? Either it does or it does not.
> 
> Thanks,
> 
>         tglx