A New Quality of Service Metric for Hard/Soft Real-Time Applications

View/ Open
Date
2003-04Author
Hua, Shaoxiong
Qu, Gang
Citation
S. Hua and G. Qu. "A New Quality of Service Metric for Hard/Soft Real-Time Applications," IEEE International Conference on Information Technology: Coding and Computing (ITCC'03), pp. 347-351, April 2003.
Metadata
Show full item recordAbstract
Real-time applications often have mixed hard and soft
deadlines, can be preempted subject to the cost of context
switching or the restart of computation, and have various
data dependency. The simple but widely used task completion
ratio, as the Quality of Service (QoS) metric, does not
capture these characteristics and can not reflect user perceived
QoS well. In this paper, we propose a new quantitative
QoS metric, which is based on task completion ratio
but differentiates hard and soft deadlines and models data
dependency as well. Basically, it assigns different weights
to hard and soft deadline tasks, penalizes late soft task
completion, and measures the tasks affected by any
dropped tasks. We apply popular online schedulers, such as
EDF (earliest deadline first), FCFS (first come first serve),
and LETF (least execution time first), on a set of simulated
MPEG movies at the frame level and for each application
compare the new QoS measurement, traditional completion
ratio with the “real” completion ratio which considers the
number of correctly decoded frames and has been mapped
to the user perceived QoS well. Experimental results show
that our proposed QoS metric can reflect real life QoS
much better than the traditional one.