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Commit bb15e7f2 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Linus Torvalds
Browse files

ibmaem: don't query the entire sensor repository when reading energy meter 



Currently, all sensors are read when the energy meter is queried via
sysfs.  This introduces a considerable amount of delay and variation in
the sysfs reading, which is not desirable when trying to profile energy
use.  Therefore, read only the energy meters when a sysfs query comes in
for them, and don't cache the results so that we always get the latest
reading.

Signed-off-by: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9c5413ea

drivers/hwmon/ibmaem.c

+13 −5
Original line number Diff line number Diff line
@@ -463,12 +463,18 @@ static int aem_read_sensor(struct aem_data *data, u8 elt, u8 reg, 
}



/* Update AEM energy registers */

static void update_aem_energy_one(struct aem_data *data, int which)

{

	aem_read_sensor(data, AEM_ENERGY_ELEMENT, which,

			&data->energy[which], 8);

}



static void update_aem_energy(struct aem_data *data)

{

	aem_read_sensor(data, AEM_ENERGY_ELEMENT, 0, &data->energy[0], 8);

	update_aem_energy_one(data, 0);

	if (data->ver_major < 2)

		return;

	aem_read_sensor(data, AEM_ENERGY_ELEMENT, 1, &data->energy[1], 8);

	update_aem_energy_one(data, 1);

}



/* Update all AEM1 sensors */
@@ -850,7 +856,7 @@ static ssize_t aem_show_power(struct device *dev, 
	struct timespec b, a;



	mutex_lock(&data->lock);

	update_aem_energy(data);

	update_aem_energy_one(data, attr->index);

	getnstimeofday(&b);

	before = data->energy[attr->index];
@@ -862,7 +868,7 @@ static ssize_t aem_show_power(struct device *dev, 
		return 0;

	}



	update_aem_energy(data);

	update_aem_energy_one(data, attr->index);

	getnstimeofday(&a);

	after = data->energy[attr->index];

	mutex_unlock(&data->lock);
@@ -881,7 +887,9 @@ static ssize_t aem_show_energy(struct device *dev, 
{

	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);

	struct aem_data *a = dev_get_drvdata(dev);

	a->update(a);

	mutex_lock(&a->lock);

	update_aem_energy_one(a, attr->index);

	mutex_unlock(&a->lock);



	return sprintf(buf, "%llu\n",

			(unsigned long long)a->energy[attr->index] * 1000);