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Date: Sun, 17 Dec 2023 17:58:45 +0000
From: Qais Yousef <qyousef@layalina.io>
To: Lukasz Luba <lukasz.luba@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	rafael@kernel.org, dietmar.eggemann@arm.com, rui.zhang@intel.com,
	amit.kucheria@verdurent.com, amit.kachhap@gmail.com,
	daniel.lezcano@linaro.org, viresh.kumar@linaro.org,
	len.brown@intel.com, pavel@ucw.cz, mhiramat@kernel.org,
	wvw@google.com
Subject: Re: [PATCH v5 05/23] PM: EM: Refactor a new function
 em_compute_costs()
Message-ID: <20231217175845.2jdeqaz62mmcjuwu@airbuntu>
References: <20231129110853.94344-1-lukasz.luba@arm.com>
 <20231129110853.94344-6-lukasz.luba@arm.com>
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In-Reply-To: <20231129110853.94344-6-lukasz.luba@arm.com>

On 11/29/23 11:08, Lukasz Luba wrote:
> Refactor a dedicated function which will be easier to maintain and re-use
> in future. The upcoming changes for the modifiable EM perf_state table
> will use it (instead of duplicating the code).

nit: What is being refactored? Looks like you took em_compute_cost() out of
em_create_perf_table().


Cheers

--
Qais Yousef

> 
> This change is not expected to alter the general functionality.
> 
> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
> ---
>  kernel/power/energy_model.c | 72 ++++++++++++++++++++++---------------
>  1 file changed, 43 insertions(+), 29 deletions(-)
> 
> diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
> index aa7c89f9e115..3bea930410c6 100644
> --- a/kernel/power/energy_model.c
> +++ b/kernel/power/energy_model.c
> @@ -103,14 +103,52 @@ static void em_debug_create_pd(struct device *dev) {}
>  static void em_debug_remove_pd(struct device *dev) {}
>  #endif
>  
> +static int em_compute_costs(struct device *dev, struct em_perf_state *table,
> +			    struct em_data_callback *cb, int nr_states,
> +			    unsigned long flags)
> +{
> +	unsigned long prev_cost = ULONG_MAX;
> +	u64 fmax;
> +	int i, ret;
> +
> +	/* Compute the cost of each performance state. */
> +	fmax = (u64) table[nr_states - 1].frequency;
> +	for (i = nr_states - 1; i >= 0; i--) {
> +		unsigned long power_res, cost;
> +
> +		if (flags & EM_PERF_DOMAIN_ARTIFICIAL) {
> +			ret = cb->get_cost(dev, table[i].frequency, &cost);
> +			if (ret || !cost || cost > EM_MAX_POWER) {
> +				dev_err(dev, "EM: invalid cost %lu %d\n",
> +					cost, ret);
> +				return -EINVAL;
> +			}
> +		} else {
> +			power_res = table[i].power;
> +			cost = div64_u64(fmax * power_res, table[i].frequency);
> +		}
> +
> +		table[i].cost = cost;
> +
> +		if (table[i].cost >= prev_cost) {
> +			table[i].flags = EM_PERF_STATE_INEFFICIENT;
> +			dev_dbg(dev, "EM: OPP:%lu is inefficient\n",
> +				table[i].frequency);
> +		} else {
> +			prev_cost = table[i].cost;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd,
>  				int nr_states, struct em_data_callback *cb,
>  				unsigned long flags)
>  {
> -	unsigned long power, freq, prev_freq = 0, prev_cost = ULONG_MAX;
> +	unsigned long power, freq, prev_freq = 0;
>  	struct em_perf_state *table;
>  	int i, ret;
> -	u64 fmax;
>  
>  	table = kcalloc(nr_states, sizeof(*table), GFP_KERNEL);
>  	if (!table)
> @@ -154,33 +192,9 @@ static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd,
>  		table[i].frequency = prev_freq = freq;
>  	}
>  
> -	/* Compute the cost of each performance state. */
> -	fmax = (u64) table[nr_states - 1].frequency;
> -	for (i = nr_states - 1; i >= 0; i--) {
> -		unsigned long power_res, cost;
> -
> -		if (flags & EM_PERF_DOMAIN_ARTIFICIAL) {
> -			ret = cb->get_cost(dev, table[i].frequency, &cost);
> -			if (ret || !cost || cost > EM_MAX_POWER) {
> -				dev_err(dev, "EM: invalid cost %lu %d\n",
> -					cost, ret);
> -				goto free_ps_table;
> -			}
> -		} else {
> -			power_res = table[i].power;
> -			cost = div64_u64(fmax * power_res, table[i].frequency);
> -		}
> -
> -		table[i].cost = cost;
> -
> -		if (table[i].cost >= prev_cost) {
> -			table[i].flags = EM_PERF_STATE_INEFFICIENT;
> -			dev_dbg(dev, "EM: OPP:%lu is inefficient\n",
> -				table[i].frequency);
> -		} else {
> -			prev_cost = table[i].cost;
> -		}
> -	}
> +	ret = em_compute_costs(dev, table, cb, nr_states, flags);
> +	if (ret)
> +		goto free_ps_table;
>  
>  	pd->table = table;
>  	pd->nr_perf_states = nr_states;
> -- 
> 2.25.1
>