linux-kernel - Re: [patch 1/3] timers: use function instead of macro for calc

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Date:	Thu, 7 May 2009 13:16:06 -0500
From:	Dimitri Sivanich <sivanich@....com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [patch 1/3] timers: use function instead of macro for calc_load

On Sat, May 02, 2009 at 07:06:31PM -0000, Thomas Gleixner wrote:
> Replace the CALC_LOAD macro by a static function.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Dimitri Sivanich <sivanich@....com>
> ---
>  include/linux/sched.h |    5 -----
>  kernel/timer.c        |   29 ++++++++++++++---------------
>  2 files changed, 14 insertions(+), 20 deletions(-)
> 
> Index: linux-2.6/include/linux/sched.h
> ===================================================================
> --- linux-2.6.orig/include/linux/sched.h
> +++ linux-2.6/include/linux/sched.h
> @@ -124,11 +124,6 @@ extern unsigned long avenrun[];		/* Load
>  #define EXP_5		2014		/* 1/exp(5sec/5min) */
>  #define EXP_15		2037		/* 1/exp(5sec/15min) */
>  
> -#define CALC_LOAD(load,exp,n) \
> -	load *= exp; \
> -	load += n*(FIXED_1-exp); \
> -	load >>= FSHIFT;
> -
>  extern unsigned long total_forks;
>  extern int nr_threads;
>  DECLARE_PER_CPU(unsigned long, process_counts);
> Index: linux-2.6/kernel/timer.c
> ===================================================================
> --- linux-2.6.orig/kernel/timer.c
> +++ linux-2.6/kernel/timer.c
> @@ -1123,14 +1123,6 @@ void update_process_times(int user_tick)
>  }
>  
>  /*
> - * Nr of active tasks - counted in fixed-point numbers
> - */
> -static unsigned long count_active_tasks(void)
> -{
> -	return nr_active() * FIXED_1;
> -}
> -
> -/*
>   * Hmm.. Changed this, as the GNU make sources (load.c) seems to
>   * imply that avenrun[] is the standard name for this kind of thing.
>   * Nothing else seems to be standardized: the fractional size etc
> @@ -1139,25 +1131,32 @@ static unsigned long count_active_tasks(
>   * Requires xtime_lock to access.
>   */
>  unsigned long avenrun[3];
> -
>  EXPORT_SYMBOL(avenrun);
>  
> +static unsigned long
> +calc_load(unsigned long load, unsigned long exp, unsigned long active)
> +{
> +	load *= exp;
> +	load += active * (FIXED_1 - exp);
> +	return load >> FSHIFT;
> +}
> +
>  /*
>   * calc_load - given tick count, update the avenrun load estimates.
>   * This is called while holding a write_lock on xtime_lock.
>   */
> -static inline void calc_load(unsigned long ticks)
> +static void calc_global_load(unsigned long ticks)
>  {
>  	unsigned long active_tasks; /* fixed-point */
>  	static int count = LOAD_FREQ;
>  
>  	count -= ticks;
>  	if (unlikely(count < 0)) {
> -		active_tasks = count_active_tasks();
> +		active_tasks = nr_active() * FIXED_1;
>  		do {
> -			CALC_LOAD(avenrun[0], EXP_1, active_tasks);
> -			CALC_LOAD(avenrun[1], EXP_5, active_tasks);
> -			CALC_LOAD(avenrun[2], EXP_15, active_tasks);
> +			avenrun[0] = calc_load(avenrun[0], EXP_1, active_tasks);
> +			avenrun[1] = calc_load(avenrun[1], EXP_5, active_tasks);
> +			avenrun[2] = calc_load(avenrun[2], EXP_15, active_tasks);
>  			count += LOAD_FREQ;
>  		} while (count < 0);
>  	}
> @@ -1193,7 +1192,7 @@ void run_local_timers(void)
>  static inline void update_times(unsigned long ticks)
>  {
>  	update_wall_time();
> -	calc_load(ticks);
> +	calc_global_load(ticks);
>  }
>  
>  /*
> 
--
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