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Date: Mon, 6 May 2024 15:01:49 +0000
From: "Yuan, Perry" <Perry.Yuan@....com>
To: "Limonciello, Mario" <Mario.Limonciello@....com>
CC: "Deucher, Alexander" <Alexander.Deucher@....com>, "Huang, Shimmer"
<Shimmer.Huang@....com>, "Du, Xiaojian" <Xiaojian.Du@....com>, "Meng, Li
(Jassmine)" <Li.Meng@....com>, "linux-pm@...r.kernel.org"
<linux-pm@...r.kernel.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "rafael.j.wysocki@...el.com"
<rafael.j.wysocki@...el.com>, "Petkov, Borislav" <Borislav.Petkov@....com>,
"Shenoy, Gautham Ranjal" <gautham.shenoy@....com>, "viresh.kumar@...aro.org"
<viresh.kumar@...aro.org>, "Huang, Ray" <Ray.Huang@....com>
Subject: RE: [PATCH v9 3/7] cpufreq: amd-pstate: implement cpb_boost sysfs
entry for boost control
[AMD Official Use Only - General]
Hi Mario,
> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@....com>
> Sent: Monday, May 6, 2024 9:28 PM
> To: Yuan, Perry <Perry.Yuan@....com>
> Cc: Deucher, Alexander <Alexander.Deucher@....com>; Huang, Shimmer
> <Shimmer.Huang@....com>; Du, Xiaojian <Xiaojian.Du@....com>; Meng,
> Li (Jassmine) <Li.Meng@....com>; linux-pm@...r.kernel.org; linux-
> kernel@...r.kernel.org; rafael.j.wysocki@...el.com; Petkov, Borislav
> <Borislav.Petkov@....com>; Shenoy, Gautham Ranjal
> <gautham.shenoy@....com>; viresh.kumar@...aro.org; Huang, Ray
> <Ray.Huang@....com>
> Subject: Re: [PATCH v9 3/7] cpufreq: amd-pstate: implement cpb_boost
> sysfs entry for boost control
>
>
>
> On 5/6/2024 5:19 AM, Perry Yuan wrote:
> > From: Perry Yuan <Perry.Yuan@....com>
> >
> > With this new sysfs entry `cpb_boost`created, user can change CPU
> > boost state dynamically under `active`, `guided` and `passive` modes.
> > And the highest perf and frequency will also be updated as the boost
> > state changing.
> >
> > 0): check current boost state
> > cat /sys/devices/system/cpu/amd_pstate/cpb_boost
> >
> > 1): disable CPU boost
> > sudo bash -c "echo 0 > /sys/devices/system/cpu/amd_pstate/cpb_boost"
> >
> > 2): enable CPU boost
> > sudo bash -c "echo 1 > /sys/devices/system/cpu/amd_pstate/cpb_boost"
> >
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=217931
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=217618
> > Signed-off-by: Perry Yuan <Perry.Yuan@....com>
>
> As I mentioned in v8, I think this makes more sense as a "per CPU attribute".
> You're already changing the MSR for each CPU when you change the global
> one.
>
> I think the only global member should be whether CPB is supported and you
> can use this for the visibility of the file each CPU.
>
> Could you justify why it's better as a global amd-ptate "driver attribute" still?
The whole patch set mainly want to support CPB switching with single global control file. That design is like the intel pstate boost.
And you know that the CPB BIOS setting option, it is not PER CPU feature as well.
Once the CPB turned off in BIOS, all the CPU boost will be disabled from kernel booting.
The per CPU control is not supported in the legacy boost control as well, I want to make the new feature patch set to allow users to switch CPB from sysfs file easily.
If we make the CPB control as PER CPU only, users need to update each CPU boost file , if the system has 192 CPUs, most of users will think it is not a convenient way to switch CPB via PER CPU control file without any users space tool support, just change it by command line.
I add a PER CPU sysfs file, user can switch CPB for specific CPU, it will not be conflicted with global sysfs, even I think most user will not use it at all.
for example, TR CPU, 192 CPUs, without script and GUI, one global sysfs will be the best choice.
Perry.
>
> > ---
> > drivers/cpufreq/amd-pstate-ut.c | 2 +-
> > drivers/cpufreq/amd-pstate.c | 114
> +++++++++++++++++++++++++++++++-
> > include/linux/amd-pstate.h | 1 +
> > 3 files changed, 115 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate-ut.c
> > b/drivers/cpufreq/amd-pstate-ut.c index f04ae67dda37..b3601b0e6dd3
> > 100644
> > --- a/drivers/cpufreq/amd-pstate-ut.c
> > +++ b/drivers/cpufreq/amd-pstate-ut.c
> > @@ -226,7 +226,7 @@ static void amd_pstate_ut_check_freq(u32 index)
> > goto skip_test;
> > }
> >
> > - if (cpudata->boost_supported) {
> > + if (amd_pstate_global_params.cpb_boost) {
> > if ((policy->max == cpudata->max_freq) ||
> > (policy->max == cpudata-
> >nominal_freq))
> > amd_pstate_ut_cases[index].result =
> AMD_PSTATE_UT_RESULT_PASS;
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index f7dab0f7b452..f81fd61dd2a9 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -686,8 +686,10 @@ static int amd_pstate_boost_init(struct
> amd_cpudata *cpudata)
> > }
> >
> > amd_pstate_global_params.cpb_supported = !(boost_val &
> MSR_K7_HWCR_CPB_DIS);
> > - if (amd_pstate_global_params.cpb_supported)
> > + if (amd_pstate_global_params.cpb_supported) {
> > current_pstate_driver->boost_enabled = true;
> > + cpudata->boost_state = true;
> > + }
> >
> > amd_pstate_global_params.cpb_boost =
> > amd_pstate_global_params.cpb_supported;
> >
> > @@ -1293,6 +1295,114 @@ static ssize_t prefcore_show(struct device
> *dev,
> > return sysfs_emit(buf, "%s\n",
> str_enabled_disabled(amd_pstate_prefcore));
> > }
> >
> > +static int amd_pstate_cpu_boost_update(struct cpufreq_policy *policy,
> > +bool on) {
> > + struct amd_cpudata *cpudata = policy->driver_data;
> > + struct cppc_perf_ctrls perf_ctrls;
> > + u32 highest_perf, nominal_perf, nominal_freq, max_freq;
> > + int ret;
> > +
> > + if (!policy) {
> > + pr_err("policy is null\n");
> > + return -ENODATA;
> > + }
> > +
> > + highest_perf = READ_ONCE(cpudata->highest_perf);
> > + nominal_perf = READ_ONCE(cpudata->nominal_perf);
> > + nominal_freq = READ_ONCE(cpudata->nominal_freq);
> > + max_freq = READ_ONCE(cpudata->max_freq);
> > +
> > + if (boot_cpu_has(X86_FEATURE_CPPC)) {
> > + u64 value = READ_ONCE(cpudata->cppc_req_cached);
> > +
> > + value &= ~GENMASK_ULL(7, 0);
> > + value |= on ? highest_perf : nominal_perf;
> > + WRITE_ONCE(cpudata->cppc_req_cached, value);
> > +
> > + wrmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ,
> value);
> > + } else {
> > + perf_ctrls.max_perf = on ? highest_perf : nominal_perf;
> > + ret = cppc_set_epp_perf(cpudata->cpu, &perf_ctrls, 1);
> > + if (ret) {
> > + cpufreq_cpu_release(policy);
> > + pr_debug("failed to set energy perf value (%d)\n",
> ret);
> > + return ret;
> > + }
> > + }
> > +
> > + if (on)
> > + policy->cpuinfo.max_freq = max_freq;
> > + else
> > + policy->cpuinfo.max_freq = nominal_freq * 1000;
> > +
> > + policy->max = policy->cpuinfo.max_freq;
> > +
> > + if (cppc_state == AMD_PSTATE_PASSIVE) {
> > + ret = freq_qos_update_request(&cpudata->req[1],
> > + policy->cpuinfo.max_freq);
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +static int amd_pstate_cpu_boost(int cpu, bool state) {
> > + int ret;
> > + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> > + struct amd_cpudata *cpudata = policy->driver_data;
> > +
> > + if (!policy) {
> > + pr_err("policy is NULL\n");
> > + ret = -ENODATA;
> > + goto err_exit;
> > + }
> > +
> > + ret = amd_pstate_cpu_boost_update(policy, state);
> > + refresh_frequency_limits(policy);
> > + cpudata->boost_state = !!state;
> > +
> > +err_exit:
> > + cpufreq_cpu_put(policy);
> > + return ret < 0 ? ret : 0;
> > +}
> > +
> > +static ssize_t cpb_boost_show(struct device *dev,
> > + struct device_attribute *attr, char *buf) {
> > + return sysfs_emit(buf, "%u\n",
> amd_pstate_global_params.cpb_boost);
> > +}
> > +
> > +static ssize_t cpb_boost_store(struct device *dev, struct device_attribute
> *b,
> > + const char *buf, size_t count) {
> > + bool new_state;
> > + ssize_t ret;
> > + int cpu;
> > +
> > + if (!amd_pstate_global_params.cpb_supported) {
> > + pr_err("Boost mode is not supported by this processor or
> SBIOS\n");
> > + return -EINVAL;
> > + }
> > +
> > + ret = kstrtobool(buf, &new_state);
> > + if (ret)
> > + return ret;
> > +
> > + mutex_lock(&amd_pstate_driver_lock);
> > + for_each_present_cpu(cpu) {
> > + ret = amd_pstate_cpu_boost(cpu, new_state);
> > + if (ret < 0) {
> > + pr_warn("failed to update cpu boost for CPU%d
> (%d)\n", cpu, ret);
> > + goto err_exit;
> > + }
> > + }
> > + amd_pstate_global_params.cpb_boost = !!new_state;
> > +
> > +err_exit:
> > + mutex_unlock(&amd_pstate_driver_lock);
> > + return ret < 0 ? ret : count;
> > +}
> > +
> > cpufreq_freq_attr_ro(amd_pstate_max_freq);
> > cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
> >
> > @@ -1303,6 +1413,7 @@
> cpufreq_freq_attr_rw(energy_performance_preference);
> > cpufreq_freq_attr_ro(energy_performance_available_preferences);
> > static DEVICE_ATTR_RW(status);
> > static DEVICE_ATTR_RO(prefcore);
> > +static DEVICE_ATTR_RW(cpb_boost);
> >
> > static struct freq_attr *amd_pstate_attr[] = {
> > &amd_pstate_max_freq,
> > @@ -1327,6 +1438,7 @@ static struct freq_attr *amd_pstate_epp_attr[] =
> {
> > static struct attribute *pstate_global_attributes[] = {
> > &dev_attr_status.attr,
> > &dev_attr_prefcore.attr,
> > + &dev_attr_cpb_boost.attr,
> > NULL
> > };
> >
> > diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> > index 8ba5dd4d3405..56f616a5cd0f 100644
> > --- a/include/linux/amd-pstate.h
> > +++ b/include/linux/amd-pstate.h
> > @@ -106,6 +106,7 @@ struct amd_cpudata {
> > u32 policy;
> > u64 cppc_cap1_cached;
> > bool suspended;
> > + bool boost_state;
> > };
> >
> > /*
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