linux-kernel - Re: [PATCH 03/12] clocksource: Remove clocksource_max

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Date:	Sat, 7 Mar 2015 10:18:35 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	John Stultz <john.stultz@...aro.org>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Dave Jones <davej@...emonkey.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Richard Cochran <richardcochran@...il.com>,
	Prarit Bhargava <prarit@...hat.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 03/12] clocksource: Remove clocksource_max_deferment()


* John Stultz <john.stultz@...aro.org> wrote:

> clocksource_max_deferment() doesn't do anything useful
> anymore, so zap it.

Well, it does something useful, it encapsulates the max_deferment 
property of the clocksource:

> -static u64 clocksource_max_deferment(struct clocksource *cs)
> -{
> -	u64 max_nsecs;
> -
> -	max_nsecs = clocks_calc_max_nsecs(cs->mult, cs->shift, cs->maxadj,
> -					  cs->mask);
> -	return max_nsecs;
> -}

Which could be written in a shorter form, using:

static u64 clocksource_max_deferment(struct clocksource *cs)
{
	return clocks_calc_max_nsecs(cs->mult, cs->shift, cs->maxadj, cs->mask);
}

Which all allows short forms of:

	cs->max_idle_ns = clocksource_max_deferment(cs);

without writing out all the arguments.

Instead of that, you've introduced:

> +	cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift,
> +						 cs->maxadj, cs->mask);

> +	cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift,
> +						 cs->maxadj, cs->mask);

Which in the next patch gets even worse:


>  	cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift,
> +						 cs->maxadj, cs->mask,
> +						 &cs->max_cycles);

>  	/* calculate max idle time permitted for this clocksource */
>  	cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift,
> +						 cs->maxadj, cs->mask,
> +						 &cs->max_cycles);

While with the helper function it would still be the same sweet:

	cs->max_idle_ns = clocksource_max_deferment(cs);

So I don't think this cleanup is an improvement ...

Thanks,

	Ingo
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