linux-kernel - Re: [PATCH] cpufreq: amd-pstate: Update policy->cur for adjust perf

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Message-ID: <ZG78k9dOJS2vauEP@BLR-5CG13462PL.amd.com>
Date:   Thu, 25 May 2023 11:43:39 +0530
From:   Wyes Karny <wyes.karny@....com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     ray.huang@....com, viresh.kumar@...aro.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        gautham.shenoy@....com
Subject: Re: [PATCH] cpufreq: amd-pstate: Update policy->cur for adjust perf

Hi Rafael,

On 24 May 19:57, Rafael J. Wysocki wrote:
> On Thu, May 18, 2023 at 7:58 AM Wyes Karny <wyes.karny@....com> wrote:
> >
> > Driver should update policy->cur after updating the frequency.
> > Currently amd_pstate doesn't update policy->cur when `adjust_perf`
> > is used. Which causes /proc/cpuinfo to show wrong cpu frequency.
> > Fix this by updating policy->cur with correct frequency value in
> > adjust_perf function callback.
> >
> > - Before the fix: (setting min freq to 1.5 MHz)
> >
> > [root@amd]# cat /proc/cpuinfo | grep "cpu MHz" | sort | uniq --count
> >       1 cpu MHz         : 1777.016
> >       1 cpu MHz         : 1797.160
> >       1 cpu MHz         : 1797.270
> >     189 cpu MHz         : 400.000
> >
> > - After the fix: (setting min freq to 1.5 MHz)
> >
> > [root@amd]# cat /proc/cpuinfo | grep "cpu MHz" | sort | uniq --count
> >       1 cpu MHz         : 1753.353
> >       1 cpu MHz         : 1756.838
> >       1 cpu MHz         : 1776.466
> >       1 cpu MHz         : 1776.873
> >       1 cpu MHz         : 1777.308
> >       1 cpu MHz         : 1779.900
> >     183 cpu MHz         : 1805.231
> >       1 cpu MHz         : 1956.815
> >       1 cpu MHz         : 2246.203
> >       1 cpu MHz         : 2259.984
> >
> > Fixes: 1d215f0319c2 ("cpufreq: amd-pstate: Add fast switch function for AMD P-State")
> >
> > Signed-off-by: Wyes Karny <wyes.karny@....com>
> > ---
> >  drivers/cpufreq/amd-pstate.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> > index 5a3d4aa0f45a..736dab69ba1e 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -479,12 +479,14 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
> >                                    unsigned long capacity)
> >  {
> >         unsigned long max_perf, min_perf, des_perf,
> > -                     cap_perf, lowest_nonlinear_perf;
> > +                     cap_perf, lowest_nonlinear_perf, max_freq;
> >         struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> >         struct amd_cpudata *cpudata = policy->driver_data;
> > +       unsigned int target_freq;
> >
> >         cap_perf = READ_ONCE(cpudata->highest_perf);
> >         lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf);
> > +       max_freq = READ_ONCE(cpudata->max_freq);
> >
> >         des_perf = cap_perf;
> >         if (target_perf < capacity)
> > @@ -501,6 +503,10 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
> >         if (max_perf < min_perf)
> >                 max_perf = min_perf;
> >
> > +       des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
> > +       target_freq = div_u64(des_perf * max_freq, max_perf);
> > +       policy->cur = target_freq;
> > +
> >         amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true,
> >                         policy->governor->flags);
> >         cpufreq_cpu_put(policy);
> > --
> 
> Applied under an edited subject, thanks!
> 
> I think you'd like this to go into 6.4 and "stable", right?

Yes, please. I should have added stable tag.

Thanks & Regards,
Wyes