06-18-2013
It is the same measurement as in "iostat". There is a sensor inside the OS for every hdisk device. This sensor either shows "busy", when the command queue of the disk is non-empty, or "idle", if it is. This sensor is queried several times per second (i have forgotten the exact rate). Then, a percentage is calculated by matching the number of "idle" answers to the number of "busy" answers.
It is in the nature of this measurement that many very small disk requests can saturate the comman buffer and make a disk "100% busy" when it effectively doesn't do that much. This does not necessarily mean the disk is at its limit, just that the command queue has never been empty. Correlate this with the I/O amount ("kb_read" and "kb_written") to get a picture about how much stress the disk is effectively exposed to.
I hope this helps.
bakunin
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LEARN ABOUT DEBIAN
sofieldsensor
SoFieldSensor(3) Coin SoFieldSensor(3)
NAME
SoFieldSensor -
The SoFieldSensor class detects changes to a field.
Attach a field to a sensor of this type to put it under surveillance, so you can act upon changes to the field.
SYNOPSIS
#include <Inventor/sensors/SoFieldSensor.h>
Inherits SoDataSensor.
Public Member Functions
SoFieldSensor (void)
SoFieldSensor (SoSensorCB *func, void *data)
virtual ~SoFieldSensor (void)
void attach (SoField *field)
void detach (void)
SoField * getAttachedField (void) const
virtual void trigger (void)
Additional Inherited Members
Detailed Description
The SoFieldSensor class detects changes to a field.
Attach a field to a sensor of this type to put it under surveillance, so you can act upon changes to the field.
An SoFieldSensor can also act for delete-callback purposes alone and does not need a regular notification-based callback.
Constructor & Destructor Documentation
SoFieldSensor::SoFieldSensor (void)
Constructor.
SoFieldSensor::SoFieldSensor (SoSensorCB *func, void *data)
Constructor taking as parameters the sensor callback function and the userdata which will be passed the callback.
See also:
setFunction(), setData()
SoFieldSensor::~SoFieldSensor (void) [virtual]
Destructor.
Member Function Documentation
void SoFieldSensor::attach (SoField *field)
Attach sensor to a field. Whenever the field's value changes, the sensor will be triggered and call the callback function.
A field sensor can be attached to only a single field at a time. When this method is invoked multiple times, each subsequent call will
replace the field the sensor is monitoring with the new field.
When the given field is deleted, the sensor will automatically be detached.
See also:
detach()
void SoFieldSensor::detach (void)
Detach sensor from field. As long as an SoFieldSensor is detached, it will never call its callback function.
See also:
attach()
SoField * SoFieldSensor::getAttachedField (void) const
Returns a pointer to the field connected to the sensor.
See also:
attach(), detach()
void SoFieldSensor::trigger (void) [virtual]
Trigger the sensor's callback function.
Reimplemented from SoDataSensor.
Author
Generated automatically by Doxygen for Coin from the source code.
Version 3.1.3 Wed May 23 2012 SoFieldSensor(3)