Configurations and Optimizations of TDMA Schedules for Periodic Packet Communication on Networks on Chip Tim Harde 1 , Matthias Freier 2 , Georg von der Br¨ uggen 1 , and Jian-Jia Chen 1 1 TU Dortmund University, Germany 2 Robert Bosch GmbH, Germany 11.10.2018 von der Br¨ uggen (TU Dortmund) 1 / 19
52
Embed
Con gurations and Optimizations of TDMA Schedules for ... · Con gurations and Optimizations of TDMA Schedules for Periodic Packet Communication on Networks on Chip Tim Harde1, Matthias
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Configurations and Optimizations of TDMASchedules for Periodic Packet Communication on
Networks on Chip
Tim Harde1, Matthias Freier2,Georg von der Bruggen1, and Jian-Jia Chen1
Example: communication task τi with ri = C0,1 and di = C2,2
⇒ route Ri : LC0,1
S0,1LS0,1S1,1
LS1,1S2,1
LS2,1S2,2
LS2,2C2,2
von der Bruggen (TU Dortmund) 6 / 19
Time Division Multiple Access (TDMA)
slot 1 slot 2 slot 3 ... slot n
TDMA frame
TDMA slot
t
Idea: partitioning the access time to a specific resource
Advantages• bandwidth guarantees
• isolation
• predictable timing behavior
• good analyzability
Problem: parameter selection: frame size, slot size and alignment
von der Bruggen (TU Dortmund) 7 / 19
Time Division Multiple Access (TDMA)
slot 1 slot 2 slot 3 ... slot n
TDMA frame
TDMA slot
t
Idea: partitioning the access time to a specific resource
Advantages• bandwidth guarantees
• isolation
• predictable timing behavior
• good analyzability
Disadvantages• global synchronization
• global overhead
• tough design problem
• empty
Problem: parameter selection: frame size, slot size and alignment
von der Bruggen (TU Dortmund) 7 / 19
Time Division Multiple Access (TDMA)
slot 1 slot 2 slot 3 ... slot n
TDMA frame
TDMA slot
t
Idea: partitioning the access time to a specific resource
Advantages• bandwidth guarantees
• isolation
• predictable timing behavior
• good analyzability
Disadvantages• global synchronization
• global overhead
• tough design problem
• empty
Problem: parameter selection: frame size, slot size and alignment
von der Bruggen (TU Dortmund) 7 / 19
Global TDMA Approach
τi τj
si sj0 ctL
• synchronous execution of the TDMA schedule on all nodes• start and end of a TDMA slot can be defined arbitrarily
⇒ unused bandwidth possible
TDMA Parameters• TDMA cycle length c
⇒ identical for all TDMA arbiters
• TDMA slot length si⇒ sufficient bandwidth to forward the flits of τi
von der Bruggen (TU Dortmund) 8 / 19
Global TDMA Approach
τi τj
si sj0 ctL
• synchronous execution of the TDMA schedule on all nodes• start and end of a TDMA slot can be defined arbitrarily
⇒ unused bandwidth possible
TDMA Parameters• TDMA cycle length c
⇒ identical for all TDMA arbiters
• TDMA slot length si⇒ sufficient bandwidth to forward the flits of τi
von der Bruggen (TU Dortmund) 8 / 19
TDMA Slot Aligning
τi
si0 ctLi1
τi
l si0 ctLi2
τi
2 · l si0 ctLi3
• align TDMA slots on consecutively traversed links⇒ immediate forwarding of flits⇒ no buffering required⇒ no flow control mechanism required (bandwidth guarantee)⇒ no contention from other packets (isolation property)
TDMA slot assignment respecting the alignment property
von der Bruggen (TU Dortmund) 9 / 19
TDMA Slot Aligning
τi
si0 ctLi1
τi
l si0 ctLi2
τi
2 · l si0 ctLi3
• align TDMA slots on consecutively traversed links⇒ immediate forwarding of flits⇒ no buffering required⇒ no flow control mechanism required (bandwidth guarantee)⇒ no contention from other packets (isolation property)
TDMA slot assignment respecting the alignment property
von der Bruggen (TU Dortmund) 9 / 19
TDMA Slot Aligning
τi
si0 ctLi1
τi
l si0 ctLi2
τi
2 · l si0 ctLi3
• align TDMA slots on consecutively traversed links⇒ immediate forwarding of flits⇒ no buffering required⇒ no flow control mechanism required (bandwidth guarantee)⇒ no contention from other packets (isolation property)
TDMA slot assignment respecting the alignment property
von der Bruggen (TU Dortmund) 9 / 19
TDMA Parameter Selection - Cycle Length
TDMA Cycle Length
• identical for all TDMA arbiters in the NoC
TDMA cycle length c ∈ {T1,T2, ...,Tn}
Harmonic Property of τ :
⇒ packets are released at the same offset of the TDMA cycle
⇒ identical response times for consecutive packet releases
Fragmentation:
• Ti < c : integer number of packets releases per TDMA cycle
• Ti = c : one packet release per TDMA cycle
• Ti > c : one packet release every Tic TDMA cycles
Directly provides the slot size si for each task
von der Bruggen (TU Dortmund) 10 / 19
TDMA Parameter Selection - Cycle Length
TDMA Cycle Length
• identical for all TDMA arbiters in the NoC
TDMA cycle length c ∈ {T1,T2, ...,Tn}
Harmonic Property of τ :
⇒ packets are released at the same offset of the TDMA cycle
⇒ identical response times for consecutive packet releases
Fragmentation:
• Ti < c : integer number of packets releases per TDMA cycle
• Ti = c : one packet release per TDMA cycle
• Ti > c : one packet release every Tic TDMA cycles
Directly provides the slot size si for each task
von der Bruggen (TU Dortmund) 10 / 19
TDMA Parameter Selection - Cycle Length
TDMA Cycle Length
• identical for all TDMA arbiters in the NoC
TDMA cycle length c ∈ {T1,T2, ...,Tn}
Harmonic Property of τ :
⇒ packets are released at the same offset of the TDMA cycle
⇒ identical response times for consecutive packet releases
Fragmentation:
• Ti < c : integer number of packets releases per TDMA cycle
• Ti = c : one packet release per TDMA cycle
• Ti > c : one packet release every Tic TDMA cycles
Directly provides the slot size si for each task
von der Bruggen (TU Dortmund) 10 / 19
TDMA Parameter Selection - Cycle Length
TDMA Cycle Length
• identical for all TDMA arbiters in the NoC
TDMA cycle length c ∈ {T1,T2, ...,Tn}
Harmonic Property of τ :
⇒ packets are released at the same offset of the TDMA cycle
⇒ identical response times for consecutive packet releases
Fragmentation:
• Ti < c : integer number of packets releases per TDMA cycle
• Ti = c : one packet release per TDMA cycle
• Ti > c : one packet release every Tic TDMA cycles
Directly provides the slot size si for each task
von der Bruggen (TU Dortmund) 10 / 19
TDMA Parameter Selection - Cycle Length
TDMA Cycle Length
• identical for all TDMA arbiters in the NoC
TDMA cycle length c ∈ {T1,T2, ...,Tn}
Harmonic Property of τ :
⇒ packets are released at the same offset of the TDMA cycle
⇒ identical response times for consecutive packet releases
Fragmentation:
• Ti < c : integer number of packets releases per TDMA cycle
• Ti = c : one packet release per TDMA cycle
• Ti > c : one packet release every Tic TDMA cycles
Directly provides the slot size si for each task
von der Bruggen (TU Dortmund) 10 / 19
TDMA Schedule Design - Overview
Given:• communication task set τ = {τ1, τ2, ..., τn}⇒ harmonic periods⇒ implicit deadlines
• r × s NoC platform
The problem is to determine
1 the TDMA cycle length
: c ∈ {T1,T2, ...,Tn}
2 the TDMA slot size si
: fragmentation, # releases
3 the offset of each TDMA slot in the TDMA cycles
all tasks can be feasibly scheduled and the TDMA slots are aligned
Approaches:
• First-Fit Greedy Heuristic
• Rectangular Scheduling (solver-based approach)
von der Bruggen (TU Dortmund) 11 / 19
TDMA Schedule Design - Overview
Given:• communication task set τ = {τ1, τ2, ..., τn}⇒ harmonic periods⇒ implicit deadlines
• r × s NoC platform
The problem is to determine
1 the TDMA cycle length
: c ∈ {T1,T2, ...,Tn}
2 the TDMA slot size si
: fragmentation, # releases
3 the offset of each TDMA slot in the TDMA cycles
all tasks can be feasibly scheduled and the TDMA slots are aligned
Approaches:
• First-Fit Greedy Heuristic
• Rectangular Scheduling (solver-based approach)
von der Bruggen (TU Dortmund) 11 / 19
TDMA Schedule Design - Overview
Given:• communication task set τ = {τ1, τ2, ..., τn}⇒ harmonic periods⇒ implicit deadlines
• r × s NoC platform
The problem is to determine
1 the TDMA cycle length: c ∈ {T1,T2, ...,Tn}2 the TDMA slot size si
: fragmentation, # releases
3 the offset of each TDMA slot in the TDMA cycles
all tasks can be feasibly scheduled and the TDMA slots are aligned
Approaches:
• First-Fit Greedy Heuristic
• Rectangular Scheduling (solver-based approach)
von der Bruggen (TU Dortmund) 11 / 19
TDMA Schedule Design - Overview
Given:• communication task set τ = {τ1, τ2, ..., τn}⇒ harmonic periods⇒ implicit deadlines
• r × s NoC platform
The problem is to determine
1 the TDMA cycle length: c ∈ {T1,T2, ...,Tn}2 the TDMA slot size si : fragmentation, # releases
3 the offset of each TDMA slot in the TDMA cycles
all tasks can be feasibly scheduled and the TDMA slots are aligned
Approaches:
• First-Fit Greedy Heuristic
• Rectangular Scheduling (solver-based approach)
von der Bruggen (TU Dortmund) 11 / 19
TDMA Schedule Design - Overview
Given:• communication task set τ = {τ1, τ2, ..., τn}⇒ harmonic periods⇒ implicit deadlines
• r × s NoC platform
The problem is to determine
1 the TDMA cycle length: c ∈ {T1,T2, ...,Tn}2 the TDMA slot size si : fragmentation, # releases
3 the offset of each TDMA slot in the TDMA cycles
all tasks can be feasibly scheduled and the TDMA slots are aligned
Approaches:
• First-Fit Greedy Heuristic
• Rectangular Scheduling (solver-based approach)
von der Bruggen (TU Dortmund) 11 / 19
TDMA Design - Greedy Heuristics
• Communication Task Scheduling• tasks are scheduled successively• tasks are scheduled in a specific order
• TDMA Slot Assignment:• start as early as possible• alignment property is maintained• isolation property is maintained (non-overlapping slots)
• Ordering Strategies:• Largest Utilization First (LUF)• Smallest Utilization First (SUF)• Largest Period First (LPF)• Smallest Period First (SPF)• Random• Largest Hop Count First + {LUF, SUF,LPF,SPF}• Hop-Count Weighted LUF (HC-W-LUF)
von der Bruggen (TU Dortmund) 12 / 19
TDMA Design - Greedy Heuristics
• Communication Task Scheduling• tasks are scheduled successively• tasks are scheduled in a specific order
• TDMA Slot Assignment:• start as early as possible• alignment property is maintained• isolation property is maintained (non-overlapping slots)
• Ordering Strategies:• Largest Utilization First (LUF)• Smallest Utilization First (SUF)• Largest Period First (LPF)• Smallest Period First (SPF)• Random• Largest Hop Count First + {LUF, SUF,LPF,SPF}• Hop-Count Weighted LUF (HC-W-LUF)
von der Bruggen (TU Dortmund) 12 / 19
TDMA Design - Greedy Heuristics
• Communication Task Scheduling• tasks are scheduled successively• tasks are scheduled in a specific order
• TDMA Slot Assignment:• start as early as possible• alignment property is maintained• isolation property is maintained (non-overlapping slots)
• Ordering Strategies:• Largest Utilization First (LUF)• Smallest Utilization First (SUF)• Largest Period First (LPF)• Smallest Period First (SPF)• Random• Largest Hop Count First + {LUF, SUF,LPF,SPF}• Hop-Count Weighted LUF (HC-W-LUF)