[PATCH v6 4/6] hwmon: (fam15h_power) Introduce a cpu accumulated power reporting algorithm

Huang Rui
2016-04-06T07:44:07Z

This patch introduces an algorithm that computes the average power by
reading a delta value of “core power accumulator” register during
measurement interval, and then dividing delta value by the length of
the time interval.

User is able to use power1_average entry to measure the processor power
consumption and power1_average_interval entry to set the interval.

A simple example:

ray@hr-ub:~/tip$ sensors
fam15h_power-pci-00c4
Adapter: PCI adapter
power1: 19.58 mW (avg = 2.55 mW, interval = 0.01 s)
(crit = 15.00 W)

...

The result is current average processor power consumption in 10
millisecond. The unit of the result is uWatt.

Suggested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Huang Rui <ray.huang@amd.com>
Cc: Borislav Petkov <bp@alien8.de>
---
drivers/hwmon/fam15h_power.c | 128 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 124 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
index 336d422..5abbfa8 100644
--- a/drivers/hwmon/fam15h_power.c
+++ b/drivers/hwmon/fam15h_power.c
@@ -27,6 +27,8 @@
#include <linux/bitops.h>
#include <linux/cpu.h>
#include <linux/cpumask.h>
+#include <linux/time.h>
+#include <linux/sched.h>
#include <asm/processor.h>
#include <asm/msr.h>

@@ -48,6 +50,9 @@ MODULE_LICENSE("GPL");
#define FAM15H_NUM_GROUPS 2
#define MAX_CUS 8

+/* set maximum interval as 1 second */
+#define MAX_INTERVAL 1000
+
#define MSR_F15H_CU_PWR_ACCUMULATOR 0xc001007a
#define MSR_F15H_CU_MAX_PWR_ACCUMULATOR 0xc001007b
#define MSR_F15H_PTSC 0xc0010280
@@ -68,6 +73,9 @@ struct fam15h_power_data {
u64 cu_acc_power[MAX_CUS];
/* performance timestamp counter */
u64 cpu_sw_pwr_ptsc[MAX_CUS];
+ /* online/offline status of current compute unit */
+ int cu_on[MAX_CUS];
+ unsigned long power_period;
};

static ssize_t show_power(struct device *dev,
@@ -149,6 +157,8 @@ static void do_read_registers_on_cu(void *_data)

rdmsrl_safe(MSR_F15H_CU_PWR_ACCUMULATOR, &data->cu_acc_power[cu]);
rdmsrl_safe(MSR_F15H_PTSC, &data->cpu_sw_pwr_ptsc[cu]);
+
+ data->cu_on[cu] = 1;
}

/*
@@ -165,6 +175,8 @@ static int read_registers(struct fam15h_power_data *data)
if (!ret)
return -ENOMEM;

+ memset(data->cu_on, 0, sizeof(int) * MAX_CUS);
+
get_online_cpus();
this_cpu = smp_processor_id();

@@ -199,6 +211,98 @@ static int read_registers(struct fam15h_power_data *data)
return 0;
}

+static ssize_t acc_show_power(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct fam15h_power_data *data = dev_get_drvdata(dev);
+ u64 prev_cu_acc_power[MAX_CUS], prev_ptsc[MAX_CUS],
+ jdelta[MAX_CUS];
+ u64 tdelta, avg_acc;
+ int cu, cu_num, ret;
+ signed long leftover;
+
+ /*
+ * With the new x86 topology modelling, x86_max_cores is the
+ * compute unit number.
+ */
+ cu_num = boot_cpu_data.x86_max_cores;
+
+ ret = read_registers(data);
+ if (ret)
+ return 0;
+
+ for (cu = 0; cu < cu_num; cu++) {
+ prev_cu_acc_power[cu] = data->cu_acc_power[cu];
+ prev_ptsc[cu] = data->cpu_sw_pwr_ptsc[cu];
+ }
+
+ leftover = schedule_timeout_interruptible(msecs_to_jiffies(data->power_period));
+ if (leftover)
+ return 0;
+
+ ret = read_registers(data);
+ if (ret)
+ return 0;
+
+ for (cu = 0, avg_acc = 0; cu < cu_num; cu++) {
+ /* check if current compute unit is online */
+ if (data->cu_on[cu] == 0)
+ continue;
+
+ if (data->cu_acc_power[cu] < prev_cu_acc_power[cu]) {
+ jdelta[cu] = data->max_cu_acc_power + data->cu_acc_power[cu];
+ jdelta[cu] -= prev_cu_acc_power[cu];
+ } else {
+ jdelta[cu] = data->cu_acc_power[cu] - prev_cu_acc_power[cu];
+ }
+ tdelta = data->cpu_sw_pwr_ptsc[cu] - prev_ptsc[cu];
+ jdelta[cu] *= data->cpu_pwr_sample_ratio * 1000;
+ do_div(jdelta[cu], tdelta);
+
+ /* the unit is microWatt */
+ avg_acc += jdelta[cu];
+ }
+
+ return sprintf(buf, "%llu\n", (unsigned long long)avg_acc);
+}
+static DEVICE_ATTR(power1_average, S_IRUGO, acc_show_power, NULL);
+
+static ssize_t acc_show_power_period(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct fam15h_power_data *data = dev_get_drvdata(dev);
+
+ return sprintf(buf, "%lu\n", data->power_period);
+}
+
+static ssize_t acc_set_power_period(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct fam15h_power_data *data = dev_get_drvdata(dev);
+ unsigned long temp;
+ int ret;
+
+ ret = kstrtoul(buf, 10, &temp);
+ if (ret)
+ return ret;
+
+ if (temp > MAX_INTERVAL)
+ return -EINVAL;
+
+ /* the interval value should be greater than 0 */
+ if (temp <= 0)
+ return -EINVAL;
+
+ data->power_period = temp;
+
+ return count;
+}
+static DEVICE_ATTR(power1_average_interval, S_IRUGO | S_IWUSR,
+ acc_show_power_period, acc_set_power_period);
+
static int fam15h_power_init_attrs(struct pci_dev *pdev,
struct fam15h_power_data *data)
{
@@ -211,6 +315,10 @@ static int fam15h_power_init_attrs(struct pci_dev *pdev,
(c->x86_model >= 0x60 && c->x86_model <= 0x7f)))
n += 1;

+ /* check if processor supports accumulated power */
+ if (boot_cpu_has(X86_FEATURE_ACC_POWER))
+ n += 2;
+
fam15h_power_attrs = devm_kcalloc(&pdev->dev, n,
sizeof(*fam15h_power_attrs),
GFP_KERNEL);
@@ -225,6 +333,11 @@ static int fam15h_power_init_attrs(struct pci_dev *pdev,
(c->x86_model >= 0x60 && c->x86_model <= 0x7f)))
fam15h_power_attrs[n++] = &dev_attr_power1_input.attr;

+ if (boot_cpu_has(X86_FEATURE_ACC_POWER)) {
+ fam15h_power_attrs[n++] = &dev_attr_power1_average.attr;
+ fam15h_power_attrs[n++] = &dev_attr_power1_average_interval.attr;
+ }
+
data->group.attrs = fam15h_power_attrs;

return 0;
@@ -290,7 +403,7 @@ static int fam15h_power_resume(struct pci_dev *pdev)
static int fam15h_power_init_data(struct pci_dev *f4,
struct fam15h_power_data *data)
{
- u32 val, eax, ebx, ecx, edx;
+ u32 val;
u64 tmp;
int ret;

@@ -317,10 +430,9 @@ static int fam15h_power_init_data(struct pci_dev *f4,
if (ret)
return ret;

- cpuid(0x80000007, &eax, &ebx, &ecx, &edx);

/* CPUID Fn8000_0007:EDX[12] indicates to support accumulated power */
- if (!(edx & BIT(12)))
+ if (!boot_cpu_has(X86_FEATURE_ACC_POWER))
return 0;

/*
@@ -328,7 +440,7 @@ static int fam15h_power_init_data(struct pci_dev *f4,
* sample period to the PTSC counter period by executing CPUID
* Fn8000_0007:ECX
*/
- data->cpu_pwr_sample_ratio = ecx;
+ data->cpu_pwr_sample_ratio = cpuid_ecx(0x80000007);

if (rdmsrl_safe(MSR_F15H_CU_MAX_PWR_ACCUMULATOR, &tmp)) {
pr_err("Failed to read max compute unit power accumulator MSR\n");
@@ -337,6 +449,14 @@ static int fam15h_power_init_data(struct pci_dev *f4,

data->max_cu_acc_power = tmp;

+ /*
+ * Milliseconds are a reasonable interval for the measurement.
+ * But it shouldn't set too long here, because several seconds
+ * would cause the read function to hang. So set default
+ * interval as 10 ms.
+ */
+ data->power_period = 10;
+
return read_registers(data);
}

--
1.9.1