RE: [PATCH v10 6/7] cpufreq: amd-pstate: introduce per CPU frequency boost control

[Yuan, Perry]

[AMD Official Use Only - General]

Regards.
Perry

> -----Original Message-----
> From: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx>
> Sent: Wednesday, May 8, 2024 5:43 PM
> To: rafael.j.wysocki@xxxxxxxxx; Limonciello, Mario
> <Mario.Limonciello@xxxxxxx>; viresh.kumar@xxxxxxxxxx; Huang, Ray
> <Ray.Huang@xxxxxxx>; Shenoy, Gautham Ranjal
> <gautham.shenoy@xxxxxxx>; Petkov, Borislav
> <Borislav.Petkov@xxxxxxx>; Yuan, Perry <Perry.Yuan@xxxxxxx>
> Cc: Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Huang, Shimmer
> <Shimmer.Huang@xxxxxxx>; Du, Xiaojian <Xiaojian.Du@xxxxxxx>; Meng,
> Li (Jassmine) <Li.Meng@xxxxxxx>; linux-pm@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v10 6/7] cpufreq: amd-pstate: introduce per CPU
> frequency boost control
>
> On středa 8. května 2024 11:34:21, SELČ Oleksandr Natalenko wrote:
> > Hello.
> >
> > On středa 8. května 2024 9:21:11, SELČ Perry Yuan wrote:
> > > Add a new sysfs attribute file to support per CPU frequency boost
> > > control, allowing individual CPUs to enable or disable CPB separately.
> > >
> > > The new sysfs attribute file is located at below path,
> > > `/sys/devices/system/cpu/cpuX/cpufreq/boost`,
> > > where `X` represents the CPU number.
> > >
> > > To disable CPB for a specific CPU, you can use the following command:
> > > $ sudo bash -c "echo 0 > /sys/devices/system/cpu/cpuX/cpufreq/boost"
> > >
> > > After disabling CPB, the CPU frequency will no longer boost beyond
> > > the base frequency for that particular CPU.
> > >
> > > for example:
> > > ----------------------------------------------------------------------
> > > CPU NODE SOCKET CORE L1d:L1i:L2:L3 ONLINE    MAXMHZ   MINMHZ
> MHZ
> > >   0    0      0    0 0:0:0:0          yes 4208.0000 400.0000 1666.7740
> > >   1    0      0    0 0:0:0:0          yes 4208.0000 400.0000  400.0000
> > >
> > > --------------------------------------------------------------------
> > > -- $ sudo bash -c "echo 0 >
> > > /sys/devices/system/cpu/cpu0/cpufreq/boost"
> > >
> > > CPU NODE SOCKET CORE L1d:L1i:L2:L3 ONLINE    MAXMHZ   MINMHZ
> MHZ
> > >   0    0      0    0 0:0:0:0          yes 3501.0000 400.0000 4154.3140
> > >   1    0      0    0 0:0:0:0          yes 4208.0000 400.0000  400.0000
> > >
> > > Please be aware that modifying the global variable
> > > `amd_pstate_global_params.cpb_boost` will overwrite the individual CPU
> settings.
> > >
> > > Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
> > > ---
> > >  drivers/cpufreq/amd-pstate.c | 27 +++++++++++++++++++++++++++
> > >  1 file changed, 27 insertions(+)
> > >
> > > diff --git a/drivers/cpufreq/amd-pstate.c
> > > b/drivers/cpufreq/amd-pstate.c index 11bce2c1db32..cb0055e7c842
> > > 100644
> > > --- a/drivers/cpufreq/amd-pstate.c
> > > +++ b/drivers/cpufreq/amd-pstate.c
> > > @@ -1371,6 +1371,30 @@ static int amd_pstate_cpu_boost(int cpu, bool
> state)
> > >   return ret < 0 ? ret : 0;
> > >  }
> > >
> > > +static ssize_t show_boost(struct cpufreq_policy *policy, char *buf)
> > > +{
> > > + struct amd_cpudata *cpudata = policy->driver_data;
> > > + bool boost_val;
> > > +
> > > + boost_val = READ_ONCE(cpudata->boost_state);
> > > +
> > > + return sysfs_emit(buf, "%u\n", boost_val); }
> > > +
> > > +static ssize_t store_boost(
> > > +         struct cpufreq_policy *policy, const char *buf, size_t count) {
> > > + bool boost_val;
> > > + int ret;
> > > +
> > > + if (sscanf(buf, "%d", &boost_val) != 1)
> >
> > This will generate warning. IIUC, sscanf() doesn't work with booleans
> directly, so you'd probably want to read the value into an (unsigned) integer,
> and then cast it to bool.
>
> …or maybe just use kstrtobool()?

Yes,  the kstrtobool is the function I need to use,  will change it in next.
Thanks
Perry.

>
> >
> > > +         return -EINVAL;
> > > +
> > > + ret = amd_pstate_cpu_boost(policy->cpu, boost_val);
> > > +
> > > + return ret < 0 ? ret : count;
> > > +}
> > > +
> > >  static ssize_t cpb_boost_show(struct device *dev,
> > >                      struct device_attribute *attr, char *buf)  { @@ -
> 1416,6
> > > +1440,7 @@ cpufreq_freq_attr_ro(amd_pstate_prefcore_ranking);
> > >  cpufreq_freq_attr_ro(amd_pstate_hw_prefcore);
> > >  cpufreq_freq_attr_rw(energy_performance_preference);
> > >  cpufreq_freq_attr_ro(energy_performance_available_preferences);
> > > +cpufreq_freq_attr_rw(boost);
> > >  static DEVICE_ATTR_RW(status);
> > >  static DEVICE_ATTR_RO(prefcore);
> > >  static DEVICE_ATTR_RW(cpb_boost);
> > > @@ -1426,6 +1451,7 @@ static struct freq_attr *amd_pstate_attr[] = {
> > >   &amd_pstate_highest_perf,
> > >   &amd_pstate_prefcore_ranking,
> > >   &amd_pstate_hw_prefcore,
> > > + &boost,
> > >   NULL,
> > >  };
> > >
> > > @@ -1437,6 +1463,7 @@ static struct freq_attr *amd_pstate_epp_attr[]
> = {
> > >   &amd_pstate_hw_prefcore,
> > >   &energy_performance_preference,
> > >   &energy_performance_available_preferences,
> > > + &boost,
> > >   NULL,
> > >  };
> > >
> > >
> >
> >
> >
>
>
> --
> Oleksandr Natalenko (post-factum)