AMD Pstate Driver Core Performance Boost

From: Perry Yuan <[email protected]>

With this new sysfs entry cpb_boostcreated, 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 <[email protected]>

---
  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(-)

drivers/cpufreq/amd-pstate-ut.c +1 -1

index f04ae67dda37..b3601b0e6dd3 100644
@@ -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;

drivers/cpufreq/amd-pstate.c +113 -1

index f7dab0f7b452..f81fd61dd2a9 100644
@@ -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
  };
 

include/linux/amd-pstate.h +1 -0

index 8ba5dd4d3405..56f616a5cd0f 100644
@@ -106,6 +106,7 @@ struct amd_cpudata {
  	u32	policy;
  	u64	cppc_cap1_cached;
  	bool	suspended;
+	bool	boost_state;
  };
 
  /*

-----Original Message-----
From: Limonciello, Mario <[email protected]>
Sent: Monday, May 6, 2024 9:28 PM
To: Yuan, Perry <[email protected]>
Cc: Deucher, Alexander <[email protected]>; Huang, Shimmer <[email protected]>; Du, Xiaojian <[email protected]>; Meng, Li (Jassmine) <[email protected]>; [email protected]; linux- [email protected]; [email protected]; Petkov, Borislav <[email protected]>; Shenoy, Gautham Ranjal <[email protected]>; [email protected]; Huang, Ray <[email protected]>
Subject: Re: [PATCH v9 3/7] cpufreq: amd-pstate: implement cpb_boost sysfs entry for boost control

Quoted 13 lines · Perry Yuan

From: Perry Yuan <[email protected]>

With this new sysfs entry cpb_boostcreated, 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"

Quoted 6 lines

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 <[email protected]>

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?

Quoted 4 lines

---
  drivers/cpufreq/amd-pstate-ut.c |   2 +-
  drivers/cpufreq/amd-pstate.c    | 114

+++++++++++++++++++++++++++++++-

Quoted 17 lines

  include/linux/amd-pstate.h      |   1 +
  3 files changed, 115 insertions(+), 2 deletions(-)

(quoted diff) +0 -0

b/drivers/cpufreq/amd-pstate-ut.c index f04ae67dda37..b3601b0e6dd3 100644

drivers/cpufreq/amd-pstate-ut.c +1 -1

@@ -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))

Quoted 1 line

amd_pstate_ut_cases[index].result =

AMD_PSTATE_UT_RESULT_PASS;

drivers/cpufreq/amd-pstate.c static int amd_pstate_boost_init(struct

Quoted 5 lines

(quoted diff) +0 -0

b/drivers/cpufreq/amd-pstate.c index f7dab0f7b452..f81fd61dd2a9 100644

drivers/cpufreq/amd-pstate.c +0 -0

@@ -686,8 +686,10 @@ static int amd_pstate_boost_init(struct

amd_cpudata *cpudata)

drivers/cpufreq/amd-pstate.c static int amd_pstate_boost_init(struct · line 688

Quoted 3 lines

drivers/cpufreq/amd-pstate.c +0 -0

    }
 
    amd_pstate_global_params.cpb_supported = !(boost_val &

MSR_K7_HWCR_CPB_DIS);

drivers/cpufreq/amd-pstate.c static ssize_t prefcore_show(struct device

Quoted 10 lines

drivers/cpufreq/amd-pstate.c +3 -1

-   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,

drivers/cpufreq/amd-pstate.c static ssize_t prefcore_show(struct device · line 1295

Quoted 1 line

drivers/cpufreq/amd-pstate.c +0 -0

    return sysfs_emit(buf, "%s\n",

str_enabled_disabled(amd_pstate_prefcore));

Quoted 17 lines

drivers/cpufreq/amd-pstate.c +15 -0

  }
 
+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);

drivers/cpufreq/amd-pstate.c static ssize_t prefcore_show(struct device *dev,

Quoted 10 lines

drivers/cpufreq/amd-pstate.c +10 -0

+   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);

drivers/cpufreq/amd-pstate.c static ssize_t prefcore_show(struct device *dev,

Quoted 6 lines

drivers/cpufreq/amd-pstate.c +6 -0

+   } 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);

Quoted 32 lines

drivers/cpufreq/amd-pstate.c +32 -0

+                   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);

drivers/cpufreq/amd-pstate.c static ssize_t prefcore_show(struct device *dev,

Quoted 10 lines

drivers/cpufreq/amd-pstate.c +10 -0

+   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);

drivers/cpufreq/amd-pstate.c static ssize_t prefcore_show(struct device *dev,

Quoted 3 lines

drivers/cpufreq/amd-pstate.c +3 -0

+}
+
+static ssize_t cpb_boost_store(struct device *dev, struct device_attribute

*b,

drivers/cpufreq/amd-pstate.c static ssize_t prefcore_show(struct device *dev,

Quoted 7 lines

drivers/cpufreq/amd-pstate.c +7 -0

+                       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");

drivers/cpufreq/amd-pstate.c static ssize_t prefcore_show(struct device *dev,

Quoted 12 lines

drivers/cpufreq/amd-pstate.c +12 -0

+           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);

drivers/cpufreq/amd-pstate.c

Quoted 14 lines

drivers/cpufreq/amd-pstate.c +10 -0

+                   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);

drivers/cpufreq/amd-pstate.c static struct freq_attr *amd_pstate_epp_attr[] =

Quoted 8 lines

drivers/cpufreq/amd-pstate.c +1 -0

  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[] =

{

Quoted 19 lines

drivers/cpufreq/amd-pstate.c +1 -0

  static struct attribute *pstate_global_attributes[] = {
    &dev_attr_status.attr,
    &dev_attr_prefcore.attr,
+   &dev_attr_cpb_boost.attr,
    NULL
  };
 

include/linux/amd-pstate.h +1 -0

index 8ba5dd4d3405..56f616a5cd0f 100644
@@ -106,6 +106,7 @@ struct amd_cpudata {
    u32     policy;
    u64     cppc_cap1_cached;
    bool    suspended;
+   bool    boost_state;
  };
 
  /*

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/amd_pstate_boost_cpb, 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/amd_pstate_boost_cpb"

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/amd_pstate_boost_cpb"

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 <[email protected]>

---
  drivers/cpufreq/amd-pstate.c | 27 +++++++++++++++++++++++++++
  1 file changed, 27 insertions(+)

drivers/cpufreq/amd-pstate.c +27 -0

index 11bce2c1db32..44531711a5fa 100644
@@ -1371,6 +1371,30 @@ static int amd_pstate_cpu_boost(int cpu, bool state)
  	return ret < 0 ? ret : 0;
  }
 
+static ssize_t show_amd_pstate_boost_cpb(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_amd_pstate_boost_cpb(
+		struct cpufreq_policy *policy, const char *buf, size_t count)
+{
+	bool boost_val;
+	int ret;
+
+	if (sscanf(buf, "%d", &boost_val) != 1)
+		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(amd_pstate_boost_cpb);
  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,
+	&amd_pstate_boost_cpb,
  	NULL,
  };
 

@@ -1437,6 +1463,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
  	&amd_pstate_hw_prefcore,
  	&energy_performance_preference,
  	&energy_performance_available_preferences,
+	&amd_pstate_boost_cpb,
  	NULL,
  };