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From: Meng Li
To: "Rafael J . Wysocki" ,
Huang Rui
CC: , ,
, ,
Shuah Khan , ,
"Nathan Fontenot" ,
Deepak Sharma ,
Alex Deucher ,
Mario Limonciello ,
Shimmer Huang , "Perry Yuan" ,
Xiaojian Du , Viresh Kumar ,
Borislav Petkov , Meng Li
Subject: [PATCH V7 3/7] cpufreq: amd-pstate: Enable amd-pstate preferred core
supporting.
Date: Mon, 18 Sep 2023 16:14:03 +0800
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amd-pstate driver utilizes the functions and data structures
provided by the ITMT architecture to enable the scheduler to
favor scheduling on cores which can be get a higher frequency
with lower voltage. We call it amd-pstate preferrred core.
Here sched_set_itmt_core_prio() is called to set priorities and
sched_set_itmt_support() is called to enable ITMT feature.
amd-pstate driver uses the highest performance value to indicate
the priority of CPU. The higher value has a higher priority.
The initial core rankings are set up by amd-pstate when the
system boots.
Add device attribute for hardware preferred core. It will check
if the processor and power firmware support preferred core
feature.
Add device attribute for preferred core. Only when hardware
supports preferred core and user set `enabled` in early parameter,
it can be set to enabled.
Add one new early parameter `disable` to allow user to disable
the preferred core.
Reviewed-by: Mario Limonciello
Co-developed-by: Perry Yuan
Signed-off-by: Perry Yuan
Signed-off-by: Meng Li
---
drivers/cpufreq/amd-pstate.c | 163 +++++++++++++++++++++++++++++++----
1 file changed, 147 insertions(+), 16 deletions(-)
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 9a1e194d5cf8..050e23594057 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -37,6 +37,7 @@
#include
#include
#include
+#include
#include
#include
@@ -49,6 +50,8 @@
#define AMD_PSTATE_TRANSITION_LATENCY 20000
#define AMD_PSTATE_TRANSITION_DELAY 1000
+#define AMD_PSTATE_PREFCORE_THRESHOLD 166
+#define AMD_PSTATE_MAX_CPPC_PERF 255
/*
* TODO: We need more time to fine tune processors with shared memory solution
@@ -65,6 +68,12 @@ static struct cpufreq_driver amd_pstate_epp_driver;
static int cppc_state = AMD_PSTATE_UNDEFINED;
static bool cppc_enabled;
+/*HW preferred Core featue is supported*/
+static bool hw_prefcore = true;
+
+/*Preferred Core featue is supported*/
+static bool prefcore = true;
+
/*
* AMD Energy Preference Performance (EPP)
* The EPP is used in the CCLK DPM controller to drive
@@ -290,23 +299,21 @@ static inline int amd_pstate_enable(bool enable)
static int pstate_init_perf(struct amd_cpudata *cpudata)
{
u64 cap1;
- u32 highest_perf;
int ret = rdmsrl_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
&cap1);
if (ret)
return ret;
- /*
- * TODO: Introduce AMD specific power feature.
- *
- * CPPC entry doesn't indicate the highest performance in some ASICs.
+ /* For platforms that do not support the preferred core feature, the
+ * highest_pef may be configured with 166 or 255, to avoid max frequency
+ * calculated wrongly. we take the AMD_CPPC_HIGHEST_PERF(cap1) value as
+ * the default max perf.
*/
- highest_perf = amd_get_highest_perf();
- if (highest_perf > AMD_CPPC_HIGHEST_PERF(cap1))
- highest_perf = AMD_CPPC_HIGHEST_PERF(cap1);
-
- WRITE_ONCE(cpudata->highest_perf, highest_perf);
+ if (hw_prefcore)
+ WRITE_ONCE(cpudata->highest_perf, AMD_PSTATE_PREFCORE_THRESHOLD);
+ else
+ WRITE_ONCE(cpudata->highest_perf, AMD_CPPC_HIGHEST_PERF(cap1));
WRITE_ONCE(cpudata->nominal_perf, AMD_CPPC_NOMINAL_PERF(cap1));
WRITE_ONCE(cpudata->lowest_nonlinear_perf, AMD_CPPC_LOWNONLIN_PERF(cap1));
@@ -318,17 +325,15 @@ static int pstate_init_perf(struct amd_cpudata *cpudata)
static int cppc_init_perf(struct amd_cpudata *cpudata)
{
struct cppc_perf_caps cppc_perf;
- u32 highest_perf;
int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
if (ret)
return ret;
- highest_perf = amd_get_highest_perf();
- if (highest_perf > cppc_perf.highest_perf)
- highest_perf = cppc_perf.highest_perf;
-
- WRITE_ONCE(cpudata->highest_perf, highest_perf);
+ if (hw_prefcore)
+ WRITE_ONCE(cpudata->highest_perf, AMD_PSTATE_PREFCORE_THRESHOLD);
+ else
+ WRITE_ONCE(cpudata->highest_perf, cppc_perf.highest_perf);
WRITE_ONCE(cpudata->nominal_perf, cppc_perf.nominal_perf);
WRITE_ONCE(cpudata->lowest_nonlinear_perf,
@@ -676,6 +681,90 @@ static void amd_perf_ctl_reset(unsigned int cpu)
wrmsrl_on_cpu(cpu, MSR_AMD_PERF_CTL, 0);
}
+/*
+ * Set amd-pstate preferred core enable can't be done directly from cpufreq callbacks
+ * due to locking, so queue the work for later.
+ */
+static void amd_pstste_sched_prefcore_workfn(struct work_struct *work)
+{
+ sched_set_itmt_support();
+}
+static DECLARE_WORK(sched_prefcore_work, amd_pstste_sched_prefcore_workfn);
+
+/*
+ * Get the highest performance register value.
+ * @cpu: CPU from which to get highest performance.
+ * @highest_perf: Return address.
+ *
+ * Return: 0 for success, -EIO otherwise.
+ */
+static int amd_pstate_get_highest_perf(int cpu, u32 *highest_perf)
+{
+ int ret;
+ u64 cppc_highest_perf;
+
+ if (boot_cpu_has(X86_FEATURE_CPPC)) {
+ u64 cap1;
+
+ ret = rdmsrl_safe_on_cpu(cpu, MSR_AMD_CPPC_CAP1, &cap1);
+ if (ret)
+ return ret;
+ WRITE_ONCE(*highest_perf, AMD_CPPC_HIGHEST_PERF(cap1));
+ } else {
+ ret = cppc_get_highest_perf(cpu, &cppc_highest_perf);
+ *highest_perf = (u32)(cppc_highest_perf & 0xFFFF);
+ }
+
+ return (ret);
+}
+
+static void amd_pstate_init_prefcore(unsigned int cpu)
+{
+ int ret;
+ u32 highest_perf;
+ static u32 max_highest_perf = 0, min_highest_perf = U32_MAX;
+
+ if (!prefcore)
+ return;
+
+ ret = amd_pstate_get_highest_perf(cpu, &highest_perf);
+ if (ret)
+ return;
+
+ /*
+ * The priorities can be set regardless of whether or not
+ * sched_set_itmt_support(true) has been called and it is valid to
+ * update them at any time after it has been called.
+ */
+ sched_set_itmt_core_prio(highest_perf, cpu);
+
+ /* check if CPPC preferred core feature is enabled*/
+ if (highest_perf == AMD_PSTATE_MAX_CPPC_PERF) {
+ pr_debug("AMD CPPC preferred core is unsupported!\n");
+ hw_prefcore = false;
+ prefcore = false;
+ return;
+ }
+
+ if (max_highest_perf <= min_highest_perf) {
+ if (highest_perf > max_highest_perf)
+ max_highest_perf = highest_perf;
+
+ if (highest_perf < min_highest_perf)
+ min_highest_perf = highest_perf;
+
+ if (max_highest_perf > min_highest_perf) {
+ /*
+ * This code can be run during CPU online under the
+ * CPU hotplug locks, so sched_set_itmt_support()
+ * cannot be called from here. Queue up a work item
+ * to invoke it.
+ */
+ schedule_work(&sched_prefcore_work);
+ }
+ }
+}
+
static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
{
int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
@@ -697,6 +786,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
cpudata->cpu = policy->cpu;
+ amd_pstate_init_prefcore(policy->cpu);
+
ret = amd_pstate_init_perf(cpudata);
if (ret)
goto free_cpudata1;
@@ -763,6 +854,22 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
return ret;
}
+static int amd_pstate_cpu_online(struct cpufreq_policy *policy)
+{
+ struct amd_cpudata *cpudata = policy->driver_data;
+
+ pr_debug("CPU %d going online\n", cpudata->cpu);
+
+ amd_pstate_init_prefcore(cpudata->cpu);
+
+ return 0;
+}
+
+static int amd_pstate_cpu_offline(struct cpufreq_policy *policy)
+{
+ return 0;
+}
+
static int amd_pstate_cpu_exit(struct cpufreq_policy *policy)
{
struct amd_cpudata *cpudata = policy->driver_data;
@@ -1037,6 +1144,12 @@ static ssize_t status_store(struct device *a, struct device_attribute *b,
return ret < 0 ? ret : count;
}
+static ssize_t prefcore_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%s\n", prefcore ? "enabled" : "disabled");
+}
+
cpufreq_freq_attr_ro(amd_pstate_max_freq);
cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
@@ -1044,6 +1157,7 @@ cpufreq_freq_attr_ro(amd_pstate_highest_perf);
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 struct freq_attr *amd_pstate_attr[] = {
&amd_pstate_max_freq,
@@ -1063,6 +1177,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
static struct attribute *pstate_global_attributes[] = {
&dev_attr_status.attr,
+ &dev_attr_prefcore.attr,
NULL
};
@@ -1114,6 +1229,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
cpudata->cpu = policy->cpu;
cpudata->epp_policy = 0;
+ amd_pstate_init_prefcore(policy->cpu);
+
ret = amd_pstate_init_perf(cpudata);
if (ret)
goto free_cpudata1;
@@ -1285,6 +1402,8 @@ static int amd_pstate_epp_cpu_online(struct cpufreq_policy *policy)
pr_debug("AMD CPU Core %d going online\n", cpudata->cpu);
+ amd_pstate_init_prefcore(cpudata->cpu);
+
if (cppc_state == AMD_PSTATE_ACTIVE) {
amd_pstate_epp_reenable(cpudata);
cpudata->suspended = false;
@@ -1389,6 +1508,8 @@ static struct cpufreq_driver amd_pstate_driver = {
.fast_switch = amd_pstate_fast_switch,
.init = amd_pstate_cpu_init,
.exit = amd_pstate_cpu_exit,
+ .offline = amd_pstate_cpu_offline,
+ .online = amd_pstate_cpu_online,
.suspend = amd_pstate_cpu_suspend,
.resume = amd_pstate_cpu_resume,
.set_boost = amd_pstate_set_boost,
@@ -1527,7 +1648,17 @@ static int __init amd_pstate_param(char *str)
return amd_pstate_set_driver(mode_idx);
}
+
+static int __init amd_prefcore_param(char *str)
+{
+ if (!strcmp(str, "disable"))
+ prefcore = false;
+
+ return 0;
+}
+
early_param("amd_pstate", amd_pstate_param);
+early_param("amd_prefcore", amd_prefcore_param);
MODULE_AUTHOR("Huang Rui ");
MODULE_DESCRIPTION("AMD Processor P-state Frequency Driver");
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From: Meng Li
To: "Rafael J . Wysocki" ,
Huang Rui
CC: , ,
, ,
Shuah Khan , ,
"Nathan Fontenot" ,
Deepak Sharma ,
Alex Deucher ,
Mario Limonciello ,
Shimmer Huang , "Perry Yuan" ,
Xiaojian Du , Viresh Kumar ,
Borislav Petkov , Meng Li
Subject: [PATCH V7 6/7] Documentation: amd-pstate: introduce amd-pstate
preferred core
Date: Mon, 18 Sep 2023 16:14:06 +0800
Message-ID: <20230918081407.756858-7-li.meng@amd.com>
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Introduce amd-pstate preferred core.
check preferred core state:
$ cat /sys/devices/system/cpu/amd-pstate/prefcore
Signed-off-by: Meng Li
---
Documentation/admin-guide/pm/amd-pstate.rst | 58 ++++++++++++++++++++-
1 file changed, 56 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
index 1cf40f69278c..b729bc6dabd8 100644
--- a/Documentation/admin-guide/pm/amd-pstate.rst
+++ b/Documentation/admin-guide/pm/amd-pstate.rst
@@ -300,8 +300,8 @@ platforms. The AMD P-States mechanism is the more performance and energy
efficiency frequency management method on AMD processors.
-AMD Pstate Driver Operation Modes
-=================================
+``amd-pstate`` Driver Operation Modes
+======================================
``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode,
non-autonomous (passive) mode and guided autonomous (guided) mode.
@@ -353,6 +353,48 @@ is activated. In this mode, driver requests minimum and maximum performance
level and the platform autonomously selects a performance level in this range
and appropriate to the current workload.
+``amd-pstate`` Preferred Core
+=================================
+
+The core frequency is subjected to the process variation in semiconductors.
+Not all cores are able to reach the maximum frequency respecting the
+infrastructure limits. Consequently, AMD has redefined the concept of
+maximum frequency of a part. This means that a fraction of cores can reach
+maximum frequency. To find the best process scheduling policy for a given
+scenario, OS needs to know the core ordering informed by the platform through
+highest performance capability register of the CPPC interface.
+
+``amd-pstate`` preferred core enables the scheduler to prefer scheduling on
+cores that can achieve a higher frequency with lower voltage. The preferred
+core rankings can dynamically change based on the workload, platform conditions,
+thermals and ageing.
+
+The priority metric will be initialized by the ``amd-pstate`` driver. The ``amd-pstate``
+driver will also determine whether or not ``amd-pstate`` preferred core is
+supported by the platform.
+
+``amd-pstate`` driver will provide an initial core ordering when the system boots.
+The platform uses the CPPC interfaces to communicate the core ranking to the
+operating system and scheduler to make sure that OS is choosing the cores
+with highest performance firstly for scheduling the process. When ``amd-pstate``
+driver receives a message with the highest performance change, it will
+update the core ranking and set the cpu's priority.
+
+``amd-pstate`` Preferred Core Switch
+=================================
+Kernel Parameters
+-----------------
+
+``amd-pstate`` peferred core`` has two states: enable and disable.
+Enable/disable states can be chosen by different kernel parameters.
+Default enable ``amd-pstate`` preferred core.
+
+``amd_prefcore=disable``
+
+For systems that support ``amd-pstate`` preferred core, the core rankings will
+always be advertised by the platform. But OS can choose to ignore that via the
+kernel parameter ``amd_prefcore=disable``.
+
User Space Interface in ``sysfs`` - General
===========================================
@@ -385,6 +427,18 @@ control its functionality at the system level. They are located in the
to the operation mode represented by that string - or to be
unregistered in the "disable" case.
+``prefcore``
+ Preferred core state of the driver: "enabled" or "disabled".
+
+ "enabled"
+ Enable the ``amd-pstate`` preferred core.
+
+ "disabled"
+ Disable the ``amd-pstate`` preferred core
+
+
+ This attribute is read-only to check the state of preferred core.
+
``cpupower`` tool support for ``amd-pstate``
===============================================
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From: Meng Li
To: "Rafael J . Wysocki" ,
Huang Rui
CC: , ,
, ,
Shuah Khan , ,
"Nathan Fontenot" ,
Deepak Sharma ,
Alex Deucher ,
Mario Limonciello ,
Shimmer Huang , "Perry Yuan" ,
Xiaojian Du , Viresh Kumar ,
Borislav Petkov , Meng Li ,
Wyes Karny
Subject: [PATCH V7 7/7] Documentation: introduce amd-pstate preferrd core mode
kernel command line options
Date: Mon, 18 Sep 2023 16:14:07 +0800
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amd-pstate driver support enable/disable preferred core.
Default enabled on platforms supporting amd-pstate preferred core.
Disable amd-pstate preferred core with
"amd_prefcore=disable" added to the kernel command line.
Signed-off-by: Meng Li
Reviewed-by: Mario Limonciello
Reviewed-by: Wyes Karny
---
Documentation/admin-guide/kernel-parameters.txt | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0a1731a0f0ef..e35b795aa8aa 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -363,6 +363,11 @@
selects a performance level in this range and appropriate
to the current workload.
+ amd_prefcore=
+ [X86]
+ disable
+ Disable amd-pstate preferred core.
+
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
Format: ,