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>
diff --git a/drivers/hwmon/ibmaem.c b/drivers/hwmon/ibmaem.c
index 08c5179..0f70dc2 100644
--- a/drivers/hwmon/ibmaem.c
+++ b/drivers/hwmon/ibmaem.c
@@ -463,12 +463,18 @@
}
/* 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 @@
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 @@
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 @@
{
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);