linux-kernel - Re: [PATCH v6 05/23] PM: EM: Refactor a new function em_compute

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Message-ID: <CAJZ5v0ij2aMzzhC3Ur0y0LSdnT0TypeH0DGSnsUPaxm6bDXcXw@mail.gmail.com>
Date: Thu, 4 Jan 2024 20:15:56 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Lukasz Luba <lukasz.luba@....com>
Cc: linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, rafael@...nel.org, 
	dietmar.eggemann@....com, rui.zhang@...el.com, amit.kucheria@...durent.com, 
	amit.kachhap@...il.com, daniel.lezcano@...aro.org, viresh.kumar@...aro.org, 
	len.brown@...el.com, pavel@....cz, mhiramat@...nel.org, qyousef@...alina.io, 
	wvw@...gle.com
Subject: Re: [PATCH v6 05/23] PM: EM: Refactor a new function em_compute_costs()

Here, I would say "Introduce em_compute_costs()" in the subject and then ->

On Thu, Jan 4, 2024 at 6:15 PM Lukasz Luba <lukasz.luba@....com> wrote:
>
> Refactor a dedicated function which will be easier to maintain and re-use

-> "Move the EM costs computation code into a new dedicated function,
em_compute_costs(), that can be reused in other places in the future."

> in future. The upcoming changes for the modifiable EM perf_state table
> will use it (instead of duplicating the code).
>
> This change is not expected to alter the general functionality.
>
> Signed-off-by: Lukasz Luba <lukasz.luba@....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
>