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

[Rafael J. Wysocki]

On Thu, May 18, 2023 at 7:58 AM Wyes Karny <wyes.karny@xxxxxxx> 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@xxxxxxx>
> ---
>  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?