linux-kernel - Re: [PATCH v8 07/10] sched: replace capacity

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Message-ID: <20141103152900.GJ12706@worktop.programming.kicks-ass.net>
Date:	Mon, 3 Nov 2014 16:29:00 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Vincent Guittot <vincent.guittot@...aro.org>
Cc:	mingo@...nel.org, linux-kernel@...r.kernel.org,
	preeti@...ux.vnet.ibm.com, Morten.Rasmussen@....com,
	kamalesh@...ux.vnet.ibm.com, linux@....linux.org.uk,
	linux-arm-kernel@...ts.infradead.org, riel@...hat.com,
	efault@....de, nicolas.pitre@...aro.org,
	linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH v8 07/10] sched: replace capacity_factor by usage

On Fri, Oct 31, 2014 at 09:47:29AM +0100, Vincent Guittot wrote:
> @@ -6414,11 +6399,12 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
>  	 */
>  	if (busiest->group_type == group_overloaded &&
>  	    local->group_type   == group_overloaded) {
> -		load_above_capacity =
> -			(busiest->sum_nr_running - busiest->group_capacity_factor);
> -
> -		load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_CAPACITY_SCALE);
> -		load_above_capacity /= busiest->group_capacity;
> +		load_above_capacity = busiest->sum_nr_running *
> +					SCHED_LOAD_SCALE;
> +		if (load_above_capacity > busiest->group_capacity)
> +			load_above_capacity -= busiest->group_capacity;
> +		else
> +			load_above_capacity = ~0UL;
>  	}
>  
>  	/*

It seems to me we no longer have need to assume each task contributes
SCHED_LOAD_SCALE, do we?

But as it stands I tihnk this patch already does too much -- it could do
with a splitting, but let me stare at is a wee bit more.
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