philips research 1st meeting of project ees.5653 29 june 2015 alina albu, [email protected] tu/e...

April 18, 2023 Alina Albu, [email protected]

TU/e Computer Science, System Architecture and NetworkingPhilips Research Laboratories Eindhoven

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1st meeting of project EES.5653

Quality of Service for In-Home Digital Networks

PROGRESS PROJECT EES.5653

Terminal QoS

M.A. Albu



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Contents

• Summary work

• Terminal QoS

• Collaboration with MRM project

• Number of context switches estimation method

• Future work



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Summary work

• Literature survey on QoS work

• QoS overview and classification of QoS improvement techniques – internal report

• Number of context switches estimation method:– 1st approach: statistical approach

– 2nd approach: min-max method

– 3rd approach: average method



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Terminal QoS

• QoS determined by resource management of the system in discussion

• Terminal resources under investigation: – CPU,

– Memory,

– Bus



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Collaboration with MRM project

• Why MRM?

– QoS related closely to resource management.

– MRM is concerned with resources management aspects in the context of a terminal.

– MRM provides opportunities for inspiration, validation of my work

• Aim MRM:

– provide methods and means for an integrated approach to resource management in multi-resource systems.

• The integrated approach has to meet at least the following requirements:

– The resource management infrastructure should be able to provide resource guarantees to the building blocks of application functionality.

– Individual building blocks should be able to limit or prevent resource insufficiencies, by dealing with insufficient resources in a graceful and predictable way.



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Collaboration with MRM project Rationale

This leads to the need for developing methods for estimating the necessary of resources for the building blocks of application but also for predicting resources necessary for the composed execution of these blocks.

• Why performance composition? - Just adding clock cycles of the involved components won’t do.

Method for the estimation of the number of context switches occurring during the execution of a streaming application.

• Current experimentation setting:

– HW: Trimedia (TM 1300) • incorporates a media processor for high-performance multimedia applications

that deal with high-quality video and audio.

– SW: TSSA



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MRM project - TSSA

TSSA – TriMedia Streaming Software Architecture

Component1 Component2 Component 3

FP Q FP Q

EP Q EP Q



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Reasons for context switch occurrence

• Blocking. The execution of a task blocks because of the following reasons:

o Communication with the PC host (ex: FRead)

o Unfavorable status of the queues:

- input full packets queue (IFPQ) is empty (no input)

- output full packets queue (OFPQ) is full (task cannot output packets for the moment)

- output empty packets queue (OEPQ) is empty (task cannot output packets for the moment)

• Preemption. The execution of a task is preempted by another task with a higher priority.

• Task execution end. The execution of a task with high priority has ended (no preemption or blocking) and the resources are allocated to another task.



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NCS Estimation MethodProperties of streaming applications executions

• Property1: Running streaming applications, after an initialization phase, adopt a pattern of execution that repeats after a specific interval of time (hyperperiod). The repetitive execution is caused by the differences in the components’ rates of production/consumption of full/empty packets.

• Execution consists of 3 phases: initialization, stable-state, finalization

• => by knowing the NCS occuring during initialization, finalization and during a hyperperiod of the steady-state, we obtain the total NCS

• Property2: When one of the components in the streaming chain is periodic, when other components depend on it in execution, their tasks will execute periodic.

Initialization

Stable-state Finalization

hyperperiod



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NCS Estimation Method Case study description

FRead VDec VRendVO

FP Q FP Q

EP Q EP Q



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NCS Estimation MethodSteps 1 – 4 : initialization, finalization phases

Step 1. Initialization phase:End phase: 169.261 msDuration: 169.261 ms Step 2.Initialization phase:NCS_initializationPhase(FRead) = 26NCS_initializationPhase (VDec) = 22NCS_initializationPhase (VRendVO) = 6 Step 3.Finalization phase:Beginning phase: 4539.029 msDuration: 1569.428 ms Step 4.Finalization phase:NCS_finalizationPhase(FRead) = 8NCS_finalizationPhase(VDec) = 356NCS_finalizationPhase(VRendVO) = 94



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NCS Estimation Method Steps 5 – 6 : stable-state phase, production/consumption rates

Step 5.

Stable state:

Beginning phase: 169.261 ms

End phase: 4539.029 ms

Duration:4369.768 ms

Step 6.

Identify for each component the full packets production rate (FPPR), the full packets consumption rate (FPCR), and the empty packets production rate (EPPR).

Priority FPPR FPCR EPPR T AT CT CEPT (ms)

FRead 90 2.2 2.524

Vdec 70 4.6 17.9 4.5 2

VrendVO 80 16.3 16.3 0.056 32.6

- measurements of components rates and computation times in isolation.



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Step 5.

Stable state:




Step 6.



FRead 90 2.2 2.524

Vdec 70 4.6 17.9 4.5 2

VrendVO 80 16.3 2*FPPR(VO) 16.3 0.056 32.6



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Step 5.

Stable state:




Step 6.



FRead 90 2.2 2.524

Vdec 70 4.6 17.9 4.5 2

VrendVO 80 16.3 2*FPPR(VO) 2*FPPR(VO) 16.3 0.056 32.6



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Step 5.

Stable state:




Step 6.


Priority FPPR FPCR EPPR T AT CT CEPT(ms)

FRead 90 2.2 2.524

Vdec 70 4.6 17.9 4*FPPR(VDec) 4.5 2




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Step 5.

Stable state:




Step 6.



FRead 90 2.2 - - 2.524 -Vdec 70 4.6 17.9 4*FPPR(VDec) 4.5 2




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NCS Estimation Method Step 7 : dependencies between components

Step 7

a - Determine the dependencies in the execution of the components by taking into consideration FPPR, FPCR and EPPR for each component.

b - Determining the dependencies in the execution of the components, leads to determining the period (T(Ti)) of each task Ti on which the components C i are mapped.

VDec:

a - FPPR (VDec) > FPCR (VRendVO) (> = rate higher) => OFPQ (VDec) at stable state is full => OEPQ (VDec) is empty => VDec depends on VRendVO to produce 1 EP so that VDec can produce 1 FP =>

FPPR (VDec) := EPPR (VRendVO) = 2 * FPPR(VrendVO) = 2 * T(VrendVO) = 32.6 ms.

=>

b - Since T(Vdec) = FPPR(VDec) => T(Vdec) = 32.6 ms



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Step 7

a - Determine the dependencies in the execution of the components by taking into consideration FPPR, FPCR and EPPR for each component.

b - Determining the dependencies in the execution of the components, leads to determining the period (T(Ti)) of each task Ti on which the components C i are mapped.

FRead:

a – FPPR (FRead) > FPCR (VDec) (> = rate higher) => OFPQ (FRead) at stable state is full => OEPQ (FRead) is empty => FRead depends on VDec to produce 1 EP so that FRead can produce 1 FP =>

FPPR (FRead) := EPPR (VDec) = 4 * FPPR(VDec) = 4 * T(VDec) = 4*2*T(VrendVO) :=130.4 ms

=>

b - Since T(FRead) = FPPR(FRead) => T(FRead) = 130.4 ms



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Step 7


FRead 90 2.2 - - 2.524 -Vdec 70 4.6 17.9 4*FPPR(VDec) 4.5 2




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Step 7


FRead 90 2.2 - - 2.524 -Vdec 70 4.6 17.9 130.4 4.5 2

VrendVO 80 16.3 32.6 32.6 16.3 0.056 32.6



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Step 7


FRead 90 130.4 - - 2.524 -Vdec 70 32.6 17.9 130.4 4.5 2

VrendVO 80 16.3 32.6 32.6 16.3 0.056 32.6



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Step 7


FRead 90 130.4 - - 130.4 2.524 -Vdec 70 32.6 17.9 130.4 32.6 4.5 2

VrendVO 80 16.3 32.6 32.6 16.3 0.056 32.6



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NCS Estimation Method Step 8 : hyperperiod length, number of hyperperiods

Step 8.

Identify hyperperiod length.

CIS (component index set) = the set of natural numbers that serve as indexes for components

in a streaming chain. The indexes of components will be equal with the indexes of the tasks on

which the components are mapped at execution.

HL = max T(Ti) = 8 * T(VRendVO) = 130.4 ms

iCIS

Duration stable phase = 4369.768 ms

=> average number of hyperperiods during stable phase:

HN = Duration_stableStatePhase/HL = 4369.768/HL = 4369.768/130.4 = 34



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NCS Estimation Method Step 9 : NCS due to blocking

Step 9.

Determine the NCS due to blocking.

FRead:

• FRead blocks 4 times for each packet that it delivers due to communication with the PC host and has its period equal with the hyperperiod (because it only gets to deliveres 1 full packet during the hyperperiod after which it blocks until the next hyperperiod) =>

NCS_blocking(FRead) = HL / T(Ti)+ NCS_inherentBlocking(FRead) =1 + 4 = 5;



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NCS Estimation Method Step 9 : NCS due to blocking

Step 9. VDec:

• VDec delivers 1 full packet every time it is activated after which it is blocked. • VDec is activated periodically and that its period fits 4 time during the hyperperiod => • VDec is activated 4 times during the hyperperiod => VDec is blocked 4 times during

the hyperperiod. NCS_blocking(VDec) = HL / T(Ti)+ NCS_inherentBlocking(VDec) = HL / T(VDEc) + 0 = 8*T(VRendVO) / 2*T(VRendVO) = 4; VRendVO:

• VRendVO is the component that does not depend on any other component in its execution, and has no inherent blockings => it does not block.

NCS_blocking(VRendVO) = 0;



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NCS Estimation Method Step 10 : NCS due to normal execution end.

Step 10.

Determine the NCS due to normal execution.

• Applies only to components that are not preempted and do not depend on any other component in its execution, thus do not get blocked.

=> Applies only to VRendVO:

NCS_normalExecutionEnd(VRendVO) = HL / T(VRendVO) = 8*T(VRendVO) / T(VRendVO) = 8



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NCS Estimation Method Step 11 : Task activation time (AT)

Step 11.

For each component by considering the dependencies dictated by the rates of production/consumption packets, calculate the first AT in the hyperperiod.

In general: For each component Ci mapped on task Ti:

1. If j CIS | Ci dependent on Cj:

If P(Ti) < P(Tj): AT(Ti) = AT(Tj) + (N-1)* FPPR(Tj) + CT(Tj) if Ti depends on Tj to release N FP.

(N-1)* EPPR(Tj) + CT(Tj) if Ti depends on Tj to release N EP.

Ti

Tj

CEPT(CFPT) EPPR(FPPR)

CT-CEPT

(CT-CFPT)

CT-CEPT

(CT-CFPT)

N=4

CT



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If P(Ti) > P(Tj): AT(Ti) = AT(Tj) + CFPT(Tj) + (N-1)* FPPR(Tj) if Ti depends on Tj to release N FP.

CEPT(Tj) + (N-1)* EPPR(Tj) if Ti depends on Tj to release N EP.

Ti

Tj

CEPT(CFPT) EPPR(FPPR)

N=4

CT



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For the current case study:

FRead: FRead dependent on Vdec to release 1 EP => P(FRead) > P(VDec) => AT(FRead) = AT(VDec) + (1-1)*EPPR(Vdec) + CEPT (VDec) = AT(VDec) + CEPT(VDec) = AT(VDec) + 2ms.Vdec: Vdec dependent on VRendVO to release 1 EP => P(VRendVO) > P(VDec) => AT(VDec) = AT(VRendVO) + (1-1)*EPPR(VRendVO) + CT (VRendVO) = AT(VRendVO) + CT (VRendVO) = AT(VRendVO) + 0.056 ms. = 0.056 ms First AT(VRendVO) = 0 relative to the beginning of the hyperperiod. => AT(FRead) = 0.056 ms +2 ms = 2.056 ms



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Step 11


FRead 90 130.4 - - 130.4 2.524 -Vdec 70 32.6 17.9 130.4 32.6 4.5 2

VrendVO 80 16.3 32.6 32.6 16.3 0.056 32.6



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Step 11


FRead 90 130.4 - - 130.4 2.056 2.524 -Vdec 70 32.6 17.9 130.4 32.6 0.056 4.5 2

VrendVO 80 16.3 32.6 32.6 16.3 0 0.056 32.6



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NCS Estimation Method Task response time, NCS due to preemptions

P(Ti) > P(Tj) AT(Ti) (AT(Tj), AT(Tj) + CT(Tj)) => Ti preempts Tj.

Ti

Tj

CT(Tj)AT(Tj)

R0(Tj) = CT(Tj)



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Ti

Tj

AT(Tj) AT(Ti)R1(Tj) = Ro(Tj)+CT(Ti)

CT(Ti)



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Ti

Tj

AT(Tj) AT(Ti) AT(Ti)R1(Tj) = Ro(Tj)+2*CT(Ti)

T(Ti)CT(Ti)



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NCS_preemption(Tj) = Ro (Tj)/T(Ti)R1(Tj) = NCS_preemption(Tj)*CT(Ti)

Ti

Tj

AT(Tj) AT(Ti) AT(Ti) R1(Tj) = Ro(Tj)+3*CT(Ti)

T(Ti)CT(Ti)

AT(Ti)



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NCS Estimation Method Step 12:Task response time, NCS due to preemptions

Step 12 Calculate NCS_preemption for all components:

In general:

Rn(Ti) = Rn-1 (Ti) + Rn-1 (Ti)/T(Tj) * CT(Tj), j {k CIS | P(Tk) > P(Ti) AT(Tk) (AT(Ti), AT(Ti) + CT(Ti))}

where Ro – initial response time, Ro(Ti) = CT(Ti)

From here, the total number of context switches due to preemptions will be:

NCS_preemption(Ti) = Rn-1 (Ti)/Tj j {k CIS | P(Tk) > P(Ti) AT(Tk) (AT(Ti), AT(Ti) + CT(Ti))}



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NCS Estimation Method Step 12:Task response time, NCS due to preemptions

Step 12 For the current case study:FRead: FRead has he highest priority assigned => never preempted. => NCS(FRead)_preemption = 0

VDec:P(VRendVO) > P(VDec) AT(VRendVO), AT(VRendVO) (AT(VDec), AT(VDec) + CT(VDec)) => VrendVO does not preempt VDec.P(FRead) > P(VDec) AT(FRead), AT(FRead) (AT(VDec), AT(VDec) + CT(VDec)) => FRead preempts VDec NCS_preemption (VDec) = 5

VRendVO:P(FRead) > P(VRendVO)

AT(FRead), AT(FRead) (AT(VRendVO), AT(VRendVO) + CT(VRendVO)) => FRead does not preempt VRendVO.

=> NCS_preemption(VRendVO)=0



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NCS Estimation Method Step 13: Total NCS/hyperperiod

Step 13

Determine NCS_total for each of the components involved:

For each hyperperiod:

NCS_total(Ci) = NCS_blocking(Ci) + NCS_preemption(Ci) + NCS_normalExecutionEnd(Ci)

=> Total NCS/hyperperiod:

NCS_hyperperiod (FRead) = NCS_blocking(FRead) + NCS_preemption(FRead) = 5 + 0=5

NCS_hyperperiod (VDec) = NCS_blocking (VDec) + NCS_preemption (VDec) = 5 + 4 = 9

NCS_hyperperiod (VRendVO) = NCS_blocking VRendVO) + NCS_preemption (VRendVO) + NCS_normalExecutionEnd(VRendVO) = 0 + 0 + 8 = 8



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NCS Estimation Method Step 14: Total NCS

Step 14

Determine the total NCS during the entire execution of the streaming application.

We know that the average number of hyperperiods during stable phase HN = 34 (from step 8)

=> Total estimated NCS:

NCS_total(FRead) = 5*34 + 26 + 8 = 204 vs measured 207

NCS_total (VDec) = 9*34 + 22 + 356 = 684 vs measured 679

NCS_total (VRendVO) = 8*34 + 6 + 94 = 372 vs measured 362

Note: Differences come from the fact that we work with averages in the components models which determines an average length for the hyperperiod and an average number of hyperperiods.



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Future work

• Test method on more complex, realistic case studies

• Write paper describing the aforementioned findings

• Extend estimation method for applications containing multiple dependent/independent chains.

• Continue studies to finding ways to estimate the necessary of memory and bus for streaming applications.

• Continue studies on estimating necessary of resources streaming applications running on multiple processors platforms.

philips research 1st meeting of project ees.5653 29 june 2015 alina albu, [email protected] tu/e...

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