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

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Message-ID: <CAJZ5v0gMqFBDubQyG3YSnt1RcGzfjnxvLtTNpCdqZDjdAMJh=w@mail.gmail.com>
Date:   Wed, 4 Aug 2021 19:00:23 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Huang Rui <ray.huang@....com>
Cc:     "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

On Tue, Aug 3, 2021 at 2:13 AM Huang Rui <ray.huang@....com> wrote:
>
> Ping~

I prefer the existing code, sorry.

> 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))
> > --