Re: [PATCH 12/15] hwmon, fam15h_power: introduce a cpu accumulated power reporting algorithm

Guenter Roeck
2015-08-27T17:30:47Z

On Thu, Aug 27, 2015 at 04:07:43PM +0800, Huang Rui wrote:
> 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_acc entry to measure the processor power
> consumption and power1_acc just needs to be read twice with an needed
> interval in-between.
>
> A simple example:
>
> $ cat /sys/bus/pci/devices/0000\:00\:18.4/hwmon/hwmon0/power1_acc
> $ sleep 10000s
> $ cat /sys/bus/pci/devices/0000\:00\:18.4/hwmon/hwmon0/power1_acc
>
> The result is current average processor power consumption in 10000
> seconds. The unit of the result is uWatt.
>
> Signed-off-by: Huang Rui <ray.huang@amd.com>
> ---
> drivers/hwmon/fam15h_power.c | 62 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 62 insertions(+)
>
> diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
> index d529e4b..3bab797 100644
> --- a/drivers/hwmon/fam15h_power.c
> +++ b/drivers/hwmon/fam15h_power.c
> @@ -60,6 +60,7 @@ struct fam15h_power_data {
> u64 cu_acc_power[MAX_CUS];
> /* performance timestamp counter */
> u64 cpu_sw_pwr_ptsc[MAX_CUS];
> + struct mutex acc_pwr_mutex;
> };
>
> static ssize_t show_power(struct device *dev,
> @@ -121,17 +122,74 @@ static DEVICE_ATTR(power1_crit, S_IRUGO, show_power_crit, NULL);
> static struct attribute_group fam15h_power_group;
> __ATTRIBUTE_GROUPS(fam15h_power);
>
> +static ssize_t show_power_acc(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + int cpu, cu, cu_num, cores_per_cu;
> + u64 curr_cu_acc_power[MAX_CUS],
> + curr_ptsc[MAX_CUS], jdelta[MAX_CUS];
> + u64 tdelta, avg_acc;
> + struct fam15h_power_data *data = dev_get_drvdata(dev);
> +
> + cores_per_cu = amd_get_cores_per_cu();
> + cu_num = boot_cpu_data.x86_max_cores / cores_per_cu;
> +
> + for (cpu = 0, avg_acc = 0; cpu < cu_num * cores_per_cu; cpu += cores_per_cu) {
> + cu = cpu / cores_per_cu;
> + if (rdmsrl_safe_on_cpu(cpu, MSR_F15H_PTSC, &curr_ptsc[cu])) {
> + pr_err("Failed to read PTSC counter MSR on core%d\n",
> + cpu);
> + return 0;
> + }
> +
> + if (rdmsrl_safe_on_cpu(cpu, MSR_F15H_CU_PWR_ACCUMULATOR,
> + &curr_cu_acc_power[cu])) {
> + pr_err("Failed to read compute unit power accumulator MSR on core%d\n",
> + cpu);
> + return 0;
> + }
> +
> + if (curr_cu_acc_power[cu] < data->cu_acc_power[cu]) {
> + jdelta[cu] = data->max_cu_acc_power + curr_cu_acc_power[cu];
> + jdelta[cu] -= data->cu_acc_power[cu];
> + } else {
> + jdelta[cu] = curr_cu_acc_power[cu] - data->cu_acc_power[cu];
> + }
> + tdelta = curr_ptsc[cu] - data->cpu_sw_pwr_ptsc[cu];
> + jdelta[cu] *= data->cpu_pwr_sample_ratio * 1000;
> + do_div(jdelta[cu], tdelta);
> +
> + mutex_lock(&data->acc_pwr_mutex);
> + data->cu_acc_power[cu] = curr_cu_acc_power[cu];
> + data->cpu_sw_pwr_ptsc[cu] = curr_ptsc[cu];
> + mutex_unlock(&data->acc_pwr_mutex);
> +
> + /* the unit is microWatt */
> + avg_acc += jdelta[cu];
> + }
> +
> + return sprintf(buf, "%u\n", (unsigned int) avg_acc);
> +}
> +static DEVICE_ATTR(power1_acc, S_IRUGO, show_power_acc, NULL);

I am not really a friend of introducing a non-standard attribute.
Does the energy attribute not work here ?

Thanks,
Guenter