Kaichen Zhao & Junhan Zhu ECE 750 Course Project PID Control for GPS
Dec 28, 2015
Content
Preliminaries 3 min Related Work 1 min Algorithms 5 min
Weighted Round Robin WF2Q+ Control Method
Experiments & Analysis 4 min
Conclusion 1 min
Preliminaries—PID Control
Why do we use PID control:Model FreeEasy to be calculated in
digital systemProportionalIntegralDerivative
Related Works—WRR and WF2Q+
Weighted Round Robin
WF2Q+- The simplest
implementation of GPS. - Each workflow is
allocated a time slice to process task in that flow
- When the time slice is used up, the server terminate the task and move to next flow
- The server will also terminate if there is no task in one workflow though this flow’s time slice hasn’t been used up
- More complicated than Round Robin
- Choose a task with the earliest finish time to transmit
- Still a approximation to GPS
- When implementing, need a virtual clock and a table to track the status of each flow
Related Works
J.A. Stankovic(Univ. of Vriginia):
- Feedback control in task scheduling/WebServer
- They introduce the idea of PID control into EDF
Tarek Ablelzaher(UIUC):
- Control of resource scheduling in complicated (MIMO) system.
- Introduce control theory to software and web system
Parameswaran Ramanathan(UW-Madison):
- Overload management
- He mainly proposed a technique for management of processor overloaded in real-time
control applications.
Algorithms—Control Method
Reference Values(Expected Util):If a queue is empty, it will give its band width to other non-empty queues.
Errors:
Experiments & Analysis
Weighted Round Robin WF2Q
Control Method
Weight SettingWorkflow1: 0.1Workflow2: 0.2Workflow3: 0.3Workflow4: 0.4
Experiments & Analysis
Algorithm Flow 1 Flow 2 Flow 3 Flow 4
Ideal 0.1 0.2 0.3 0.4
Weighted Round Robin
0.01016 0.1980 0.2993 0.4011
WF2Q 0.10005 0.19712 0.29989 0.40193
Control Method 0.10010 0.20060 0.30030 0.39940
Utilization Comparison
Experiments & Analysis
Weighted Round Robin WF2Q
Control Method
Weight SettingWorkflow1: 0.1Workflow2: 0.2Workflow3: 0.3Workflow4: 0.4
Experiments & Analysis
Algorithm Flow 1 Flow 2 Flow 3 Flow 4
Weighted Round Robin
33.94 28.59 30.24 25.16
WF2Q 39.66 17.10 10.32 7.30
Control Method 40.12 16.60 10.11 7.37
Average Response Time Comparison
Experiments & Analysis
Algorithm Average Response Time
Variance of Response Time
UtilizationError
Weighted Round Robin
29.56 711.95 0.00396
WF2Q 19.17 1276 0.00497
Control Method 19.17 1213 0.00016
Response Time Comparison
Experiments & Analysis
Algorithm Float point computation number
Branch number
Parameter size
Weighted Round Robin
12 * flow number
5 3 * flow number + 2
WF2Q 14 * flow number
8 3 * flow number + 2
Control Method 16 * flow number
6 5 * flow number + 2
Complexity
Future work
We didn’t research in deep to see how PID parameters will influence the performance
Find better problems to be solved by PID control
Summary
We proposed a new method to implement GPS: Based on the idea of PID control Make schedule decision according
to the error between the real utilization and expected utilization
We did some literature research on related topics: GPS Control theory in RTS
Summary
Compared with two other algorithms by writing three programs and one application
Did some analysis and experiments on control method and two classical methods.