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Subject: Re: [patch 2/3] sched: fix minimum power returned by
 update_cpu_power()
From: Peter Zijlstra <peterz@infradead.org>
To: Suresh Siddha <suresh.b.siddha@intel.com>
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Date: Mon, 16 Aug 2010 09:50:37 +0200
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On Fri, 2010-08-13 at 12:45 -0700, Suresh Siddha wrote:
> plain text document attachment (fix_update_cpu_power.patch)
> Default cpu_power needs to be multiples of SCHED_LOAD_SCALE and not '1'.
> Fix it.
> 
> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
> ---
>  kernel/sched_fair.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: tree/kernel/sched_fair.c
> ===================================================================
> --- tree.orig/kernel/sched_fair.c
> +++ tree/kernel/sched_fair.c
> @@ -2309,7 +2309,7 @@ static void update_cpu_power(struct sche
>  	power >>= SCHED_LOAD_SHIFT;
>  
>  	if (!power)
> -		power = 1;
> +		power = SCHED_LOAD_SCALE;
>  

                            smt_power   freq_power    rt_power
power = SCHED_LOAD_SCALE * ---------- * ---------- * ----------
                           LOAD_SCALE   LOAD_SCALE   LOAD_SCALE

Which, in the above case ends up being 0, so how does resetting it back
to LOAD_SCALE make sense?