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From: Oleksandr Natalenko <oleksandr@natalenko.name>
To: rafael.j.wysocki@intel.com, Mario.Limonciello@amd.com,
 viresh.kumar@linaro.org, Ray.Huang@amd.com, gautham.shenoy@amd.com,
 Borislav.Petkov@amd.com, Perry Yuan <perry.yuan@amd.com>
Cc: Alexander.Deucher@amd.com, Xinmei.Huang@amd.com, Xiaojian.Du@amd.com,
 Li.Meng@amd.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject:
 Re: [PATCH v10 6/7] cpufreq: amd-pstate: introduce per CPU frequency boost
 control
Date: Wed, 08 May 2024 11:43:26 +0200
Message-ID: <1884700.tdWV9SEqCh@natalenko.name>
In-Reply-To: <12430678.O9o76ZdvQC@natalenko.name>
References:
 <cover.1715152592.git.perry.yuan@amd.com>
 <49204c6d4a334c0bfbc589dda79b5cd7c4c28b7c.1715152592.git.perry.yuan@amd.com>
 <12430678.O9o76ZdvQC@natalenko.name>
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From: Oleksandr Natalenko <oleksandr@natalenko.name>
Date: Wed, 08 May 2024 11:43:26 +0200
Message-ID: <1884700.tdWV9SEqCh@natalenko.name>
In-Reply-To: <12430678.O9o76ZdvQC@natalenko.name>
MIME-Version: 1.0

On st=C5=99eda 8. kv=C4=9Btna 2024 11:34:21, SEL=C4=8C Oleksandr Natalenko =
wrote:
> Hello.
>=20
> On st=C5=99eda 8. kv=C4=9Btna 2024 9:21:11, SEL=C4=8C 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.
> >=20
> > The new sysfs attribute file is located at below path,
> > `/sys/devices/system/cpu/cpuX/cpufreq/boost`,
> > where `X` represents the CPU number.
> >=20
> > 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"
> >=20
> > After disabling CPB, the CPU frequency will no longer boost beyond
> > the base frequency for that particular CPU.
> >=20
> > 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
> >=20
> > ----------------------------------------------------------------------
> > $ sudo bash -c "echo 0 > /sys/devices/system/cpu/cpu0/cpufreq/boost"
> >=20
> > 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
> >=20
> > Please be aware that modifying the global variable
> > `amd_pstate_global_params.cpb_boost` will overwrite the individual CPU =
settings.
> >=20
> > Signed-off-by: Perry Yuan <perry.yuan@amd.com>
> > ---
> >  drivers/cpufreq/amd-pstate.c | 27 +++++++++++++++++++++++++++
> >  1 file changed, 27 insertions(+)
> >=20
> > 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 st=
ate)
> >  	return ret < 0 ? ret : 0;
> >  }
> > =20
> > +static ssize_t show_boost(struct cpufreq_policy *policy, char *buf)
> > +{
> > +	struct amd_cpudata *cpudata =3D policy->driver_data;
> > +	bool boost_val;
> > +
> > +	boost_val =3D 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) !=3D 1)
>=20
> This will generate warning. IIUC, sscanf() doesn't work with booleans dir=
ectly, so you'd probably want to read the value into an (unsigned) integer,=
 and then cast it to bool.

=E2=80=A6or maybe just use kstrtobool()?

>=20
> > +		return -EINVAL;
> > +
> > +	ret =3D 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[] =3D {
> >  	&amd_pstate_highest_perf,
> >  	&amd_pstate_prefcore_ranking,
> >  	&amd_pstate_hw_prefcore,
> > +	&boost,
> >  	NULL,
> >  };
> > =20
> > @@ -1437,6 +1463,7 @@ static struct freq_attr *amd_pstate_epp_attr[] =
=3D {
> >  	&amd_pstate_hw_prefcore,
> >  	&energy_performance_preference,
> >  	&energy_performance_available_preferences,
> > +	&boost,
> >  	NULL,
> >  };
> > =20
> >=20
>=20
>=20
>=20


=2D-=20
Oleksandr Natalenko (post-factum)
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