[patch] RT: calc_load() uses wrong variable to calculate RT load

[patch] RT: calc_load() uses wrong variable to calculate RT load

[Frank Rowand]

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.

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;
 

Re: [patch] RT: calc_load() uses wrong variable to calculate RT load

[Thomas Gleixner]

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;
>  
>