Re: [PATCH v2 07/10] hwmon: (fam15h_power) Introduce a cpu accumulated power reporting algorithm

[Borislav Petkov]

On Tue, Oct 20, 2015 at 10:28:26AM +0800, Huang Rui wrote:
> This patch introduces an algorithm that computes the average power by
> reading a delta value of âcore power accumulatorâ 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:       23.73 mW (avg = 634.63 mW, interval =   0.01 s)
>                        (crit =  15.00 W)
> 
> ...

I need to play with this more after I get back from KS. Just a partial
review for now.

> 
> The result is current average processor power consumption in 10
> millisecond. The unit of the result is uWatt.
> 
> Suggested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> ---
>  drivers/hwmon/fam15h_power.c | 120 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 120 insertions(+)
> 
> diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
> index 6321f73..a5a539e 100644
> --- a/drivers/hwmon/fam15h_power.c
> +++ b/drivers/hwmon/fam15h_power.c
> @@ -26,6 +26,9 @@
>  #include <linux/pci.h>
>  #include <linux/bitops.h>
>  #include <linux/cpumask.h>
> +#include <linux/mutex.h>
> +#include <linux/time.h>
> +#include <linux/sched.h>
>  #include <asm/processor.h>
>  #include <asm/msr.h>
>  
> @@ -64,6 +67,10 @@ 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;
> +	struct mutex acc_pwr_mutex;
>  };
>  
>  static ssize_t show_power(struct device *dev,
> @@ -132,11 +139,15 @@ static void do_read_registers_on_cu(void *_data)
>  	cores_per_cu = amd_get_cores_per_cu();
>  	cu = cpu / cores_per_cu;
>  
> +	mutex_lock(&data->acc_pwr_mutex);
>  	WARN_ON(rdmsrl_safe(MSR_F15H_CU_PWR_ACCUMULATOR,
>  			    &data->cu_acc_power[cu]));
>  
>  	WARN_ON(rdmsrl_safe(MSR_F15H_PTSC,
>  			    &data->cpu_sw_pwr_ptsc[cu]));
> +
> +	data->cu_on[cu] = 1;
> +	mutex_unlock(&data->acc_pwr_mutex);
>  }
>  
>  static int read_registers(struct fam15h_power_data *data)
> @@ -148,6 +159,10 @@ static int read_registers(struct fam15h_power_data *data)
>  	cores_per_cu = amd_get_cores_per_cu();
>  	cu_num = boot_cpu_data.x86_max_cores / cores_per_cu;
>  
> +	mutex_lock(&data->acc_pwr_mutex);
> +	memset(data->cu_on, 0, sizeof(int) * MAX_CUS);
> +	mutex_unlock(&data->acc_pwr_mutex);
> +
>  	WARN_ON_ONCE(cu_num > MAX_CUS);
>  
>  	ret = zalloc_cpumask_var(&mask, GFP_KERNEL);
> @@ -184,18 +199,113 @@ 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, cores_per_cu, ret;
> +	signed long leftover;
> +
> +	cores_per_cu = amd_get_cores_per_cu();
> +	cu_num = boot_cpu_data.x86_max_cores / cores_per_cu;
> +
> +	ret = read_registers(data);
> +	if (ret)
> +		return 0;
> +
> +	cu = 0;
> +	while(cu++ < cu_num) {
> +		prev_cu_acc_power[cu] = data->cu_acc_power[cu];
> +		prev_ptsc[cu] = data->cpu_sw_pwr_ptsc[cu];
> +	}

Please integrate checkpatch into your workflow of creating patches - it
can be correct sometimes:

ERROR: space required before the open parenthesis '('
#130: FILE: drivers/hwmon/fam15h_power.c:221:
+       while(cu++ < cu_num) {


> +
> +	leftover = schedule_timeout_interruptible(
> +			msecs_to_jiffies(data->power_period)
> +		   );

This way of writing a function call is reaaally ugly. What's wrong with:

	leftover = schedule_timeout_interruptible(msecs_to_jiffies(data->power_period));

?

And don't tell me 80 columns - that rule is not a hard one.

> +	if (leftover)
> +		return 0;
> +

...

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix ImendÃrffer, Jane Smithard, Graham Norton, HRB 21284 (AG NÃrnberg)
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