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Date: Wed, 6 May 2009 10:44:59 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Frank Rowand <frank.rowand@am.sony.com>
cc: mingo@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [patch] RT: calc_load() uses wrong variable to calculate RT
 load
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On Tue, 5 May 2009, Frank Rowand wrote:

> In calc_load() use RT tasks to calculate the RT load.
> 
> Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
> 
> ---
> 
> Ingo,
> 
> In calc_load():
> 
> #ifdef CONFIG_PREEMPT_RT
>                 active_rt_tasks = count_active_rt_tasks();
> #endif
> 
> but active_rt_tasks is then not used.  I have not read through enough code
> to verify my supposition, but the obvious use of this variable would be for
> the calculation of the RT load average.
> 
> If my supposition is correct, this patch fixes the problem.

Yep, that's correct. Though I ponder to get rid of avenrun_rt all
together.

Thanks,

	tglx

> The patch is compile tested only.
> 
> -Frank Rowand
> Sony Corporation of America
> 
> 
> Index: linux-2.6.29.2/kernel/timer.c
> ===================================================================
> --- linux-2.6.29.2.orig/kernel/timer.c
> +++ linux-2.6.29.2/kernel/timer.c
> @@ -1249,9 +1249,9 @@ static inline void calc_load(unsigned lo
>  			CALC_LOAD(avenrun[1], EXP_5, active_tasks);
>  			CALC_LOAD(avenrun[2], EXP_15, active_tasks);
>  #ifdef CONFIG_PREEMPT_RT
> -			CALC_LOAD(avenrun_rt[0], EXP_1, active_tasks);
> -			CALC_LOAD(avenrun_rt[1], EXP_5, active_tasks);
> -			CALC_LOAD(avenrun_rt[2], EXP_15, active_tasks);
> +			CALC_LOAD(avenrun_rt[0], EXP_1, active_rt_tasks);
> +			CALC_LOAD(avenrun_rt[1], EXP_5, active_rt_tasks);
> +			CALC_LOAD(avenrun_rt[2], EXP_15, active_rt_tasks);
>  #endif
>  			count += LOAD_FREQ;
>  
>