Regarding the Optimality of Speedup Bounds of Mixed-Criticality - - PowerPoint PPT Presentation
Regarding the Optimality of Speedup Bounds of Mixed-Criticality Schedulability Tests Zhishan Guo Department of Computer Science, Missouri S&T Presented at Dagstuhl Seminar 17131 Mar. 29, 2017 MC & Vestals Interpretation Mixed
Department of Computer Science, Missouri S&T Presented at Dagstuhl Seminar 17131
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
Mode switch ci
L
ci
H
t Static Analysis; Pessimistic Measurement Based; Optimistic
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
Mode switch ci
L
ci
H
t Static Analysis; Pessimistic Measurement Based; Optimistic
Q: Why Mixed Criticality? A: The resources over-provisioned to the critical functionalities can be used to execute the less- critical functionalities instead.
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
– Important & Interesting: 300+ papers in 8 years [1] – Hard [2]
Mode switch ci
L
ci
H
t Static Analysis; Pessimistic Measurement Based; Optimistic
Q: Why Mixed Criticality? A: The resources over-provisioned to the critical functionalities can be used to execute the less- critical functionalities instead.
[1] A Burns and R Davis. Mixed-criticality systems, a review. 9th ed, 2017. [2] S Baruah. Mixed criticality scheduling is highly intractable, 2008.
NP-Hard in the strong sense
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
– Important, Interesting, & Hard
Mode switch
Speedup Bound
Strategy Work Uniprocessor, Vestal Job 1.618, Best OCBP [Baruah, Li, Soutgie RTAS’10] Uniprocessor, Vestal Task 4/3, Best EDF-VD [Li & Baruah RTSS’10] [Baruah et al. ECRTS’12] Multi processor, Vestal Task 1.618 4/3 MC-Fluid [Lee et al. RTSS’14] 4/3, Best MCF [Our Work, RTSS’15]
A schedulability test has speedup factor s, s≥1, if any task set that is schedulable by any algorithm on platform with processing speed of 1, it will be deemed schedulable by this test upon a processor that is s times as fast.
NP-Hard in the strong sense
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
– Important, Interesting, & Hard
Mode switch
Speedup Bound
Strategy Work Uniprocessor, Vestal Job 1.618, Best OCBP [Baruah, Li, Soutgie RTAS’10] Uniprocessor, Vestal Task 4/3, Best EDF-VD [Li & Baruah RTSS’10] [Baruah et al. ECRTS’12] Multi processor, Vestal Task 1.618 4/3 MC-Fluid [Lee et al. RTSS’14] 4/3, Best MCF [Our Work, RTSS’15]
A schedulability test has speedup factor s, s≥1, if any task set that is schedulable by any algorithm on platform with processing speed of 1, it will be deemed schedulable by this test upon a processor that is s times as fast.
NP-Hard in the strong sense
“Optimal” Strategy
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
– Important, Interesting, & Hard
Mode switch
Speedup Bound
Strategy Work Uniprocessor, Vestal Job 1.618, Best OCBP [Baruah, Li, Stougie RTAS’10] Uniprocessor, Vestal Task 4/3, Best EDF-VD [Li & Baruah RTSS’10] [Baruah et al. ECRTS’12] Multi processor, Vestal Task 1.618 4/3 MC-Fluid [Lee et al. RTSS’14] 4/3, Best MCF [Our Work, RTSS’15]
A schedulability test has speedup factor s, s≥1, if any task set that is schedulable by any algorithm on platform with processing speed of 1, it will be deemed schedulable by this test upon a processor that is s times as fast.
NP-Hard in the strong sense
“Optimal” Strategy
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
– Important, Interesting, & Hard
Speedup Bound
Strategy Work Uniprocessor, Vestal Job 1.618, Best OCBP [Baruah, Li, Soutgie RTAS’10] Uniprocessor, Vestal Task 4/3, Best EDF-VD [Li & Baruah RTSS’10] [Baruah et al. ECRTS’12] Multi processor, Vestal Task 1.618 4/3 Best MC-Fluid [Lee et al. RTSS’14] 4/3, Best MCF [Our Work, RTSS’15]
A schedulability test has speedup factor s, s≥1, if any task set that is schedulable by any algorithm on platform with processing speed of 1, it will be deemed schedulable by this test upon a processor that is s times as fast.
DOMINATE
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
– Important, Interesting, & Hard
Speedup Bound
Strategy Work Uniprocessor, Vestal Job 1.618, Best OCBP [Baruah, Li, Soutgie RTAS’10] Uniprocessor, Vestal Task 4/3, Best EDF-VD [Li & Baruah RTSS’10] [Baruah et al. ECRTS’12] Multi processor, Vestal Task 1.618 4/3 Best MC-Fluid [Lee et al. RTSS’14] 4/3, Best MCF [Our Work, RTSS’15]
A schedulability test has speedup factor s, s≥1, if any task set that is schedulable by any algorithm on platform with processing speed of 1, it will be deemed schedulable by this test upon a processor that is s times as fast.
Demand-Based MC [Easwaran, RTSS’13] [Ekberg & Yi, RTS 50(1)] DOMINATE
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
– Important, Interesting, & Hard
Speedup Bound
Strategy Work Uniprocessor, Vestal Job 1.618, Best OCBP [Baruah, Li, Soutgie RTAS’10] Uniprocessor, Vestal Task 4/3, Best EDF-VD [Li & Baruah RTSS’10] [Baruah et al. ECRTS’12] Multi processor, Vestal Task 1.618 4/3 Best MC-Fluid [Lee et al. RTSS’14] 4/3, Best MCF [Our Work, RTSS’15]
Lazy Priority Adjustment [Gu et al., RTCSA’13] LE-EDF [Guo & Baruah, RTNS’15] DOMINATE
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
– Important, Interesting, & Hard
Mode switch
Speedup Bound
Strategy Work Uniprocessor, Vestal Job 1.618, Best OCBP [Baruah, Li, Soutgie RTAS’10] Uniprocessor, Vestal Task 4/3, Best EDF-VD [Li & Baruah RTSS’10] [Baruah et al. ECRTS’12] Multi processor, Vestal Task 1.618 4/3 MC-Fluid [Lee et al. RTSS’14] 4/3, Best MCF [Our Work, RTSS’15]
A schedulability test has speedup factor s, s≥1, if any task set that is schedulable by any algorithm on platform with processing speed of 1, it will be deemed schedulable by this test upon a processor that is s times as fast.
NP-Hard in the strong sense
“Optimal” clairvoyant Strategy
NECESSARY CONDITIONS SUFFICIENT CONDITIONS
– MC: functionalities of different degree of importance are implemented upon a shared platform. – MC Correctness:
– Important, Interesting, & Hard
Speedup Bound
Strategy Work Uniprocessor, Vestal Job 1.618, Best OCBP [Baruah, Li, Soutgie RTAS’10] Uniprocessor, Vestal Task 4/3, Best EDF-VD [Li & Baruah RTSS’10] [Baruah et al. ECRTS’12] Multi processor, Vestal Task 1.618 4/3 Best MC-Fluid [Lee et al. RTSS’14] 4/3, Best MCF [Our Work, RTSS’15]
Lazy Priority Adjustment [Gu et al., RTCSA’13] LE-EDF [Guo & Baruah, RTNS’15]
Chairman of IBM, 1943
President of Digital Equipment Corporation, 1977
– Provide ideal schedule for multiprocessor – Each task τi executes at a given rate θi
– Provide ideal schedule for multiprocessor – Each task τi executes at a given rate θi
– A task τi is executed with
· LO-rate θi
L under normal mode
· HI-rate θi
H after mode switch
Fig from [WMC 2015]
Mode switch ci
L
ci
H
t Static Analysis; Pessimistic Measurement Based; Optimistic
– Provide ideal schedule for multiprocessor – Each task τi executes at a given rate θi
– A task τi is executed with
· LO-rate θi
L under normal mode
· HI-rate θi
H after mode switch
– Proof Idea
Fig from [WMC 2015]
Any task set that is schedulable on a c-speed platform: Will be schedulable by MCF
SUFFICIENT NECESSARY
c c c
– Provide ideal schedule for multiprocessor – Each task τi executes at a given rate θi
– A task τi is executed with
· LO-rate θi
L under normal mode
· HI-rate θi
H after mode switch
– Proof Idea
Fig from [WMC 2015]
Any task set that is schedulable on a ¾-speed platform: Will be schedulable by MCF
SUFFICIENT NECESSARY
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