New performance measures, detailed examples, modeling of error detection process, performance evaluation of rollback recovery methods, experiments on FTMP, and optimal size of an NMR cluster are discussed

Shin, K. G.

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https://ntrs.nasa.gov/search.jsp?R=19830027381 2020-03-21T01:08:30+00:00Z
•_	 0 R	 • s -
STATUS REPORT
on the Grant Project Entitled
"Performance and Evaluation of Real-Time Multicomputer Control Systems"
-.w
1CQ'
COY
By
Kang G. Shin
Department of Electrical and Computer Engineering
The University of Michigan
Ann Arbor, Michigan 48109
(313) 763-0391
XV,'4
OCT 1983
RECEIVED
NASA STl MOM .
ACCESS DEPT. _y^1
Prepared for:
NASA Langley Research Center
Hampton, Virginia 23665
Attention: Ricky W. Butler
Grant No. NAG 1-296
August 1983
(NASA-CR-173075) PERFORMANCE AND EVALCATICN
	 W83-35E52
OF REAL-TIME MULTICCMEUTER CCNTFCL SYSTEMS
Status Report, Sep. 1982 - Aug. 1983
jllichigan Univ.) 6 p HC AC2/MF A01 CSCL S8B
	 Unclas
G3/60 1502`_
e	 %
Kang G. Shin. Status Report
1. INTRODUCTION
In this status report, we briefly outline the research accomplishments and
activities during the period of September 1982 - August 1983.
The overall goal of this project Is to develop a structured method for design and
evaluation of real-time multicomputers/multiprocessors.
2. SUMMARY OF ACCOMPLISHMENTS
2.1. New Performance Measures
This work arose as a result of a rea;: . -ion that conventional performance meas-
ures are inappropriate and even misleading when used to characterize real-time sys-
tems such as aircraft. We have developed a set of performance measures for real-
time control systems. These have been s .-_.vn to be more appropriate than conven-
tional measures. For details, see [1],[2],[8]. As a result of these new measures, the
solution of several interesting problems such as the number-power tradeoff, the allo-
cation of tasks to processors, and the optimai share-out of control information among
distributed controllers has been facilitated.
2.2. Detailed Examples
To check the applicability of the performance measures to real-life systems, two
typical examples are studied in detail; an idealized communications satellite [2] and
an aircraft in the final stages of its landing [7],[9]. These examples ha , fe served to
refine our performance measures and have lent them credibility.
2.3. Modeling of Error Detection Process
This is a microscopic view of real-time computers. In other words, error detec-
tion process is one of the fundamental issues that affect the overall performance of
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Kang G. Shin: Status Report
real-time computers. In this work, we have proposed a model to describe the entire
error detection process. The detection mechanisms are divided Into three classes
which are signal level, function level detection mechanisms and diagnostic. For each
class, we assign different performance measure and use these measures to evaluate
detection capability of the whole system. When these detection mechanisms are nei-
ther perfect nor complete, the system will suffer from two undesirable results; one is
the probability of putting out potentially erroneous results, the other is the additional
recovery overhead. With the proposed model, we estimate these two effects and
then discuss the design problem associated with the error detection proccbs. Finally,
the feasible space for detection mechanisms is outlined. For further details, see
[3],[10].
2.4. Performance Evaluation of Rollback Recovery Methods
The principle of rollback recovery method is to save process states during the
normal execution and to use the saved states for rescuing the failed process after
an error is detected. To begin with, we consider the asynchronous recovery blocks
and estimate the interval between two successive recovery lines which is the upper
bound of rollback distance for this case. Then, two refinements of this asynchronous
method: synchronized recovery blocks and pseudo recovery points, are discussed in
regard to their overheads and performance. For details, see [4],[5].
2.5. Experiments on FTMP
Two experiments on FTMP were begun, and are expected to be completed by
the end of this year. These are an investigation of paging in the FTMP, and error gen-
eration and detection. From the first experiment, a computation of the optimal page
size will become possible. From the second, some experimental data for one of the
error detection models described above will be obtained.
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Kang G. Shin: Status Report
2.6. Optimal Size of an NMR Cluster
Due to the considerable overhead involved in voting and Byzantine general algo-
rithms in an NMR cluster, increasing the size of the cluster to provide greater redun-
dance is not always profitable. We have begun t;, develop an algorithm that will
accept as inputs timing constraints and run-times of the individual computational
jobs, the failure law of the processors, a.nd the nature of the voting/Byzantine algo-
rithm and produce as output, for a selected set of interconnection structures, the
optimal number of processors in an NMR cluster. This work should be complete by the
end of this year.
3. PARTICIPATING PERSONNEL
• Dr. Byung Kook Kim: visiting researcher in the area of r3al-time control
• Chandrasekar Mani Krishna: Ph.D. student
• Yann-Hang Lee: Ph. D. student
• Michael Woodbury: M. S. student
4. TRAVEL
- C. M. Krishna: attended the 20th Annual Allerton Conf. on Communications, Control,
and Computing, University of Illinois, Urbana-Champaigne, IL., October 1982.
• K. G. Shin: visited NASA Langley Research Center for research review, January
1983.
• K. G. Shin: attended the IEEE Workshop for Reliable Computing Laboratories, NASA
Langley Research Center, April 1983.
• K. G. Shin: attended the Performance'83, University of Maryland, College Park, MD.,
May 1983.
• K. G. Shin: attended the 13t Fault-Tolerant Computing Symposium, Milan, Italy, June
1983.
• C. M. Krishna and Y.-H. Lee: visited Airlab, NASA Langley Research Center, August
1983.
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Kang G. Shin: Status Report
• K. G. Shin and Y.-H. Lee: attended the 1983 International Conference on Parallel
Processing, Bellaire, MI, August 1983.
• K. G. Shin and C. M. Krishna: attended the 1983 SIGMETRICS Conference, Minneapo-
lis, MN., August 1983.
5. TECHNICAL PAPERS AND REPORTS UNDER THE GRANT SUPPORT
The following technical papers/reports present in some detail the work accom-
plished thus far.
[1] C. M. Krishna and K. G. Shin, "Performance Measures for Fault-Tolerant Mul-
tiprocessor Controllers for Critical Processes," Proc, of the 20th Annual All-
erton Conf. on Communications, Control, and Computing, University of Illi-
nois, IL, October 1982.
[2] C. M. Krishna and K. G. Shin, "Performance Measures for Multiprocessor Con-
trollers," Periormance'83, A. K. Agrawala and S. K. Tripathi (eds.), North-
Holland, pp. 229-250, 1983. and also published as Computing Research
Laboratory Report, CRL-TR-1-82, University of Michigan, October 1982.
[3] K. G. Shin and Y. H. Lee, "Analysis of the Impact of Error Detection on Computer
Performance," Digest of FTCS-13, and also published as Computing
Research Laboratory Report, CRL-TR-2-82, University of Michigan, November
1982.
[4] Y. H. Lee and K. G. Shin, "Design and Evaluation of a Fault-Tolerant Multipro-
cessor Using Hardware Recovery Blocks," to appear in IEEE Trans. on Com-
puters, and also published as Computing Research Laboratory Report,
CRL-TR-6-82, University of Michigan, September 1982.
[5] K. G. Shin and Y. - H. Lee, "Analysis of Backward Error Recovery for Concurrent
Processes with Recovery Blocks", Proc, of the 1983 International Conf, on
Parallel Processing, Bellaire, MI, August 23-26, 1983. (Also this is being
considered for IEEE Trans. on Software Engineering),
[6] C. M. Krishna and K. G. Shin, "Queueing Analysis of a Canonical Model of Real-
Time Multiprocessors", Proc. 1983 ACM SIGMETRICS Conf, on Measurement
and Modelling of Computer Systems, Minneapolis, MN, August 29-31, 1983.
[7] K. G. Shin, C. M. Krishna, and Y. - H. Lee, "The Application to the Aircraft Land-
ing Problem of a Unified Method for Characterizing Real-Time Systems," To
appear in Proc. of Real-Time Systems Symposium, Arlington, VA., December
6-8, 1983.
[8] K. G. Shin and C. M. Krishna, "New Pertormance Measures for Design and
Evaluation of Real-Time Multiprocessors," submitted to IEEE Trans, on Com-
puters.
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Kang G. Shin: Status Report
[9] K. G. Shin, C. M. Krishna, and Y. - H. Lee, "A Unified Method for Evaluating
Real-Time Computer Controllers: A Case Study," submitted to IEEE Trans, on
Computers.
[10] K. G. Shin and Y. - H. Lee, "Error Detection Process: Model, Design, and Its
Impact on Computer Performance," submitted to IEEE Trans. on Computers.
[11 ] C. M. Krishna, K. G. Shin, and Y. - H. Lee, "On Optimiza'_ion Criteria for Check-
point Placement", submitted to Communi-,ations of ACM.
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Performance and evaluation of real-time multicomputer control systems

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