Criteria For Performance Evaluation
UTILIZATION The fraction of time a device is in use. ( ratio of in-use time / total observation time )
THROUGHPUT The number of job completions in a period of time. (jobs / second )
SERVICE TIME The time required by a device to handle a request. (seconds)
QUEUEING TIME Time on a queue waiting for service from the device. (seconds)
RESIDENCE TIME The time spent by a request at a device.
RESIDENCE TIME = SERVICE TIME + QUEUEING TIME.
RESPONSE TIME Time used by a system to respond to a User Job. ( seconds )
THINK TIME The time spent by the user of an interactive system to figure out the next
request. (seconds)
The goal is to optimize both the average and the amount of variation. (but beware the ogre predictability.)