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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: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Darrick J. Wong 2008-08-15 00:40:41 -07:00 committed by Linus Torvalds
parent 9c5413eac5
commit bb15e7f286
1 changed files with 13 additions and 5 deletions
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18
drivers/hwmon/ibmaem.c
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@ -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);