linux-kernel - Re: [PATCH V2 2/2] cpufreq: Optimize cpufreq_frequency_table

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Date:	Thu, 2 Jun 2016 06:59:04 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Steve Muckle <steve.muckle@...aro.org>
Cc:	Rafael Wysocki <rjw@...ysocki.net>, linaro-kernel@...ts.linaro.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH V2 2/2] cpufreq: Optimize cpufreq_frequency_table_target()

On 01-06-16, 12:46, Steve Muckle wrote:
> >  	/*
> >  	 * Find the closest frequency above target_freq.
> > -	 *
> > -	 * The table is sorted in the reverse order with respect to the
> > -	 * frequency and all of the entries are valid (see the initialization).
> >  	 */
> > -	entry = policy->freq_table;
> > -	do {
> > -		entry++;
> > -		freq = entry->frequency;
> > -	} while (freq >= target_freq && freq != CPUFREQ_TABLE_END);
> > -	entry--;
> > +	index = cpufreq_frequency_table_target(policy, target_freq,
> > +					       CPUFREQ_RELATION_L);
> 
> This adds a function call to the fast path...

I understand that, but I am not sure how far should we go to avoid
that. Open coding routines to save on that isn't a good idea surely.

I have at least kept this routine in cpufreq.h to avoid a call, but
eventually we will have at least a call somewhere within it. :(

-- 
viresh