linux-kernel - Re: [PATCH] cpufreq: enhance the sequency of governor change

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Message-ID: <20210803001339.GG2563957@hr-amd>
Date:   Tue, 3 Aug 2021 08:13:39 +0800
From:   Huang Rui <ray.huang@....com>
To:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: enhance the sequency of governor change

Ping~

On Wed, Jul 21, 2021 at 06:16:58PM +0800, Huang, Ray wrote:
> Keep the "success" case of governor change in the mainline of the
> function not in "if" case. And using restart_old_gov flag to indicate
> the fallback case to old governor. This is more readable and no function
> change.
> 
> Signed-off-by: Huang Rui <ray.huang@....com>
> ---
>  drivers/cpufreq/cpufreq.c | 23 +++++++++++++++--------
>  1 file changed, 15 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 802abc925b2a..4f7005ddb70c 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2545,18 +2545,25 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
>  	/* start new governor */
>  	policy->governor = new_gov;
>  	ret = cpufreq_init_governor(policy);
> -	if (!ret) {
> -		ret = cpufreq_start_governor(policy);
> -		if (!ret) {
> -			pr_debug("governor change\n");
> -			sched_cpufreq_governor_change(policy, old_gov);
> -			return 0;
> -		}
> +	if (ret)
> +		goto restart_old_gov;
> +
> +	ret = cpufreq_start_governor(policy);
> +	if (ret) {
>  		cpufreq_exit_governor(policy);
> +		goto restart_old_gov;
>  	}
>  
> +	pr_debug("governor change\n");
> +
> +	sched_cpufreq_governor_change(policy, old_gov);
> +
> +	return 0;
> +
> +restart_old_gov:
>  	/* new governor failed, so re-start old one */
> -	pr_debug("starting governor %s failed\n", policy->governor->name);
> +	pr_debug("starting governor %s failed\n",
> +		 policy->governor->name);
>  	if (old_gov) {
>  		policy->governor = old_gov;
>  		if (cpufreq_init_governor(policy))
> -- 
> 2.25.1
>