1. Standards and Patterns for Dynamic Resource Management
Lonnie R. Welch
Center for Intelligent, Distributed and Dependable Systems
School of EECS
Ohio University

2. Overview solution patterns for common problems
typically, at least three solutions exist
a solid basis for standardization

3. The Common Problems Characterizing the system and its requirements
Monitoring system performance
Allocating resources to meet objectives

4. Characterizing a System
Hardware
profiling
Characterizing
a system and
its requirements
Software
profiling
Specification

5. Hardware Profile
Knowledge of the host resource performance abilities is needed
Heterogeneous hardware platforms
Need a means for normalizing performance abilities

6. Hardware Profile
SPEC: benchmark and metrics for evaluation of computers
18 different programs measure CPU, memory and compiler
SPECint: a measure of a host's fixed point performance
SPECfp: a measure of a host's floating point performance
Normalization: compare to a reference host
SPEC_RATE(Hi) = AVG(SPECint(Hi)/ Max(SPECin(Hj), SPECfp(Hi)/Max(SPECfp(Hj)))

7. Software Profile
A dynamic real-time system may process varying amounts of data
Ensuring that dynamic real-time system requirements are met is a difficult task if there is no way to determine the amount of processing, memory and communication required to operate in a particular environmental context
Resource usage patterns at various workloads should be characterized to enable effective online allocation analysis

8. Software Profile
Y. Zhou, L.R. Welch, E. Huh, et al., "Execution Time Analysis for Dynamic, Periodic Processes," Proc. 9th Workshop on Parallel and Distributed Real-Time Systems (WPDRTS), April 2001.

9. System Specification
To derive a feasible allocation of a DRTS to resources, it is necessary to understand
the characteristics of the resources
the characteristics of the DRTS
the constraints and objectives
How are these features described?
The descriptions should be factored out from the components, to facilitate easy modification

10. System Specification PATH Sensing { Connectivity{…}
Type…; // periodic, event-driven, hybrid.
Criticality 5; //
RealTimeQoS{…}
Scalability{…}
DATASTREAM{…}
} // end PATH sensing

11. The Common Problems Characterizing the system and its requirements
Monitoring system performance
Allocating resources to meet objectives

12. Monitoring QoS information monitoring QoS information reporting
Resource monitoring
Allocation policing

13. QoS Information Reporter
The resource needs of a DRTS change during execution
Also, the real-time performance of a DRTS can vary
How does an application make its resource needs and QoS-relevant performance metrics known?

14. QoS Information Reporter
Provides methods for gathering and communicating the following:
CPU utilization
communication needs
memory usage
the amount of time taken to handle one activation
the workload

15. QoS Information Reporter
S.Brandt, et al., “A dynamic quality of service middleware agent for mediating application resource usage,” Proc. 19th IEEE Real-Time Systems Symposium, 307–317, IEEE Computer Society, Los Alamitos, CA, 1998.

16. QoS Monitor Gather and analyze info. regarding QoS and workload
Aggregate process-level events into a single QoS metric
Determine when to adapt the resource allocation

17. QoS Monitor
F. Jahanian, “Run-Time Monitoring of Real-Time Systems,” Advances in Real-Time Systems, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1995.

18. Resource Monitor Determine the status and utilization of the resources
Track the historical utilization values and trends
Provide aggregate load indices (e.g., host load index)
Enables evaluation of current and proposed allocations

19. Real-Time Applications
Resource Monitor
Real-Time Applications
instr
RM-SPEC
S/W
&
H/W
QoS Managers
Resource
requests
negotiations
Resource Allocations
Resource Managers
instr
ctrl
ctrl
instr
Compute. h/w
Comm. h/w

20. Allocation Policer
Reduce the number of violations via proactive analysis
Determine when analysis should be performed
Proactively trigger reallocation of resources
Determine
if a DRTS is likely to violate any of its QoS constraints
if feasibility analysis should be activated
if instability is occurring
if current allocation can be improved significantly

21. Allocation Policer analysis policing monitoring
Flow diagram for an Allocation Policer.
E. Huh and L.R. Welch, “Toward Schedulability Analysis for Dynamic Real-Time Systems,” IEEE Real-Time Technology and Applications Symposium – WIP, June 2000.

22. The Common Problems Characterizing the system and its requirements
Monitoring system performance
Allocating resources to meet objectives

23. Allocating Resources Enact Optimize Allocation Analyze Feasibility
Estimate Performance

24. Performance Estimator
Determine what the real-time performance will be when a particular allocation is enacted
Analytically determine the real-time performance of distributed systems that contend for resources
Use the Hardware and Software Profiles, the QoS and Resource Monitor, and the System Specification

25. Performance Estimator
Predict the real-time QoS by modeling CPU contention
pred(ai, tl, Ht) = Cpred(ai, tl, Ht) + Dpred(ai, tl, Ht)
Cpred(ai,tl,Ht) = Cprof(ai,tl,Hk)*SPEC_RATE(Hk)/SPEC_RATE(Ht)
Dpred(ai, tl, Ht) = Cpred(ai, tl, Ht) * CUP(Ht,t) / Trate

26. Performance Estimator
Response time predictions for a filtering application.
E. Huh, A. Neelamegam, L. Welch, H. Park and B. Pfarr “Worst-Case Analysis for Real-Time Processes in Time-Sharing Environments,” Journal of Parallel and Distributed Computing Practices, to appear.

27. Feasibility Analyzer Find allocations that meet real-time constraints
Predicted response time,
Application requirement
<application>, <host> 1
Predict Response
Time 2
Check Schedulability
Schedulability
Analysis result
Resource
Manager
Find allocations that meet real-time constraints
pred(ai) /  req(ai)  1, i
Requires the Latency Estimation and the System Specification patterns

28. Allocation Optimizer
Find an allocation such that all applications can be scheduled feasibly and it is optimal
Objectives include load balancing, maximization of slack, and optimization of utility

29. Allocation Optimizer

30. Allocation Enactor
Provide a means of executing resource allocation decisions
Examples include:
Process migration
Process replication
Adjustment of algorithm fidelity
Route selection
Resource reservation

31. Real-Time Applications
Allocation Enactor
Real-Time Applications
instr
RM-SPEC
S/W
&
H/W
QoS Managers
Resource
requests
negotiations
Resource Allocations
Resource Managers
instr
ctrl
ctrl
instr
Compute. h/w
Comm. h/w

32. Needed Standards
System characterization
Monitoring
Allocation