linux-kernel - Re: [PATCH] cpufreq: p4-clockmod: Replace bool_int_array[NR

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Date:	Sun, 27 Sep 2015 18:10:33 +0200
From:	Jean Delvare <jdelvare@...e.de>
To:	Denys Vlasenko <dvlasenk@...hat.com>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Ingo Molnar <mingo@...nel.org>,
	Bartosz Golaszewski <bgolaszewski@...libre.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Benoit Cousson <bcousson@...libre.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Jonathan Corbet <corbet@....net>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: p4-clockmod: Replace bool_int_array[NR_CPUS]
 with bitmap

Hi Denys,

On Sat, 26 Sep 2015 14:47:18 +0200, Denys Vlasenko wrote:
> Straigntforward conversion from
>     int has_N44_O17_errata[NR_CPUS]
> to
>     DECLARE_BITMAP(has_N44_O17_errata, NR_CPUS)
> 
> Saves about 2 kbytes in bss for NR_CPUS=512.
> 
> Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
> CC: Viresh Kumar <viresh.kumar@...aro.org>
> CC: Rafael J. Wysocki <rjw@...ysocki.net>
> CC: Ingo Molnar <mingo@...nel.org>
> CC: Bartosz Golaszewski <bgolaszewski@...libre.com>
> CC: H. Peter Anvin <hpa@...or.com>
> CC: Benoit Cousson <bcousson@...libre.com>
> CC: Fenghua Yu <fenghua.yu@...el.com>
> CC: Guenter Roeck <linux@...ck-us.net>
> CC: Jean Delvare <jdelvare@...e.de>
> CC: Jonathan Corbet <corbet@....net>
> CC: Peter Zijlstra <peterz@...radead.org>
> CC: Thomas Gleixner <tglx@...utronix.de>
> CC: x86@...nel.org
> CC: linux-kernel@...r.kernel.org
> ---
>  drivers/cpufreq/p4-clockmod.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cpufreq/p4-clockmod.c b/drivers/cpufreq/p4-clockmod.c
> index 5dd95da..dd15810 100644
> --- a/drivers/cpufreq/p4-clockmod.c
> +++ b/drivers/cpufreq/p4-clockmod.c
> @@ -49,7 +49,7 @@ enum {
>  #define DC_ENTRIES	8
>  
>  
> -static int has_N44_O17_errata[NR_CPUS];
> +static DECLARE_BITMAP(has_N44_O17_errata, NR_CPUS);
>  static unsigned int stock_freq;
>  static struct cpufreq_driver p4clockmod_driver;
>  static unsigned int cpufreq_p4_get(unsigned int cpu);
> @@ -66,7 +66,7 @@ static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate)
>  	if (l & 0x01)
>  		pr_debug("CPU#%d currently thermal throttled\n", cpu);
>  
> -	if (has_N44_O17_errata[cpu] &&
> +	if (test_bit(cpu, has_N44_O17_errata) &&
>  	    (newstate == DC_25PT || newstate == DC_DFLT))
>  		newstate = DC_38PT;
>  
> @@ -182,7 +182,7 @@ static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
>  	case 0x0f0a:
>  	case 0x0f11:
>  	case 0x0f12:
> -		has_N44_O17_errata[policy->cpu] = 1;
> +		set_bit(policy->cpu, has_N44_O17_errata);
>  		pr_debug("has errata -- disabling low frequencies\n");
>  	}
>  
> @@ -199,7 +199,7 @@ static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
>  
>  	/* table init */
>  	for (i = 1; (p4clockmod_table[i].frequency != CPUFREQ_TABLE_END); i++) {
> -		if ((i < 2) && (has_N44_O17_errata[policy->cpu]))
> +		if ((i < 2) && test_bit(policy->cpu, has_N44_O17_errata))
>  			p4clockmod_table[i].frequency = CPUFREQ_ENTRY_INVALID;
>  		else
>  			p4clockmod_table[i].frequency = (stock_freq * i)/8;

Looks good, however I think you should #include <linux/bitmap.h> to
avoid build failures in the future or on certain architectures.

-- 
Jean Delvare
SUSE L3 Support
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