linux-kernel - Re: [PATCH 3/3 linux-next] cpufreq: conservative: Use an inline function to evaluate freq

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Date:	Fri, 22 Mar 2013 00:51:59 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Stratos Karafotis <stratosk@...aphore.gr>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>, cpufreq@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3 linux-next] cpufreq: conservative: Use an inline function to evaluate freq_target

On Wednesday, March 06, 2013 04:15:41 PM Stratos Karafotis wrote:
> On 03/06/2013 03:23 PM, Viresh Kumar wrote:
> > Atleast my poor mind can't make out how. To me it looks like broken now.
> > 
> > 
> > When can we enter this "if" block, probably only in case where max freq is
> > less than 100 KHz (And because we have freq unit in KHz in cpufreq, its exact
> > value is less than 100). Lets say its 90.
> > 
> > So, we will get into your "if" block now and would set freq_target to 90 - 5000.
> > 
> > So its broken, isn't it.
> > 
> > Rest is fine.
> > 
> 
> Of course your are right. I'm sorry for this confusion.
> 
> Below v2 of this patch.
> 
> Thanks,
> Stratos
> 
> --------------------------------8<------------------------
> Use an inline function to evaluate freq_target to avoid duplicate code.
> 
> Also, define a macro for the default frequency step.
> 
> Signed-off-by: Stratos Karafotis <stratosk@...aphore.gr>

This one didn't apply for me to linux-pm.git/bleeding-edge.  Care to rebase?

Rafael


> ---
>  drivers/cpufreq/cpufreq_conservative.c | 27 +++++++++++++++------------
>  1 file changed, 15 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
> index 08be431..3fb921d 100644
> --- a/drivers/cpufreq/cpufreq_conservative.c
> +++ b/drivers/cpufreq/cpufreq_conservative.c
> @@ -28,6 +28,7 @@
>  /* Conservative governor macros */
>  #define DEF_FREQUENCY_UP_THRESHOLD		(80)
>  #define DEF_FREQUENCY_DOWN_THRESHOLD		(20)
> +#define DEF_FREQUENCY_STEP			(5)
>  #define DEF_SAMPLING_DOWN_FACTOR		(1)
>  #define MAX_SAMPLING_DOWN_FACTOR		(10)
>  
> @@ -39,9 +40,20 @@ static struct cs_dbs_tuners cs_tuners = {
>  	.down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
>  	.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
>  	.ignore_nice = 0,
> -	.freq_step = 5,
> +	.freq_step = DEF_FREQUENCY_STEP,
>  };
>  
> +static inline unsigned int get_freq_target(struct cpufreq_policy *policy)
> +{
> +	unsigned int freq_target = (cs_tuners.freq_step * policy->max) / 100;
> +
> +	/* max freq cannot be less than 100. But who knows... */
> +	if (unlikely(freq_target == 0))
> +		freq_target = DEF_FREQUENCY_STEP;
> +
> +	return freq_target;
> +}
> +
>  /*
>   * Every sampling_rate, we check, if current idle time is less than 20%
>   * (default), then we try to increase frequency. Every sampling_rate *
> @@ -55,7 +67,6 @@ static void cs_check_cpu(int cpu, unsigned int load)
>  {
>  	struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
>  	struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
> -	unsigned int freq_target;
>  
>  	/*
>  	 * break out if we 'cannot' reduce the speed as the user might
> @@ -72,13 +83,7 @@ static void cs_check_cpu(int cpu, unsigned int load)
>  		if (dbs_info->requested_freq == policy->max)
>  			return;
>  
> -		freq_target = (cs_tuners.freq_step * policy->max) / 100;
> -
> -		/* max freq cannot be less than 100. But who knows.... */
> -		if (unlikely(freq_target == 0))
> -			freq_target = 5;
> -
> -		dbs_info->requested_freq += freq_target;
> +		dbs_info->requested_freq += get_freq_target(policy);
>  		if (dbs_info->requested_freq > policy->max)
>  			dbs_info->requested_freq = policy->max;
>  
> @@ -94,9 +99,7 @@ static void cs_check_cpu(int cpu, unsigned int load)
>  
>  	/* Check for frequency decrease */
>  	if (load < cs_tuners.down_threshold) {
> -		freq_target = (cs_tuners.freq_step * policy->max) / 100;
> -
> -		dbs_info->requested_freq -= freq_target;
> +		dbs_info->requested_freq -= get_freq_target(policy);
>  		if (dbs_info->requested_freq < policy->min)
>  			dbs_info->requested_freq = policy->min;
>  
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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