Khalid Latif1, Amir-Mohammad Rahmani1, Tiberiu Seceleanu2, Hannu Tenhunen1
1University of Turku, Finland. 2ABB Corporate Research, Västerås, Sweden
Power- and Performance-Aware IP Mapping for NoC-
Based MPSoC Platforms
2
Outline
• Networks-on-Chip (NoCs)
• Problem
• Allocation/Placement
• Prioritization
• Placement Algorithm
• Comparison with existing techniques
3
Networks-on-Chip
• An on-chip interconnection.• Approach extracted from computer networks.• Communication resources increase with the number of cores.• Abstraction between computation and communication.• Sophiticated routing algorithms.• Plug and play platform.• Solution for 100s of cores on a single chip.
router router router
router router router
router router router
router router router
DSP Mem
PE0
Mem
PE1 PE2
UP
ACC CoP Arb
Ctrl Mng
router
router
router
router
FPU
ALU
MPEG
MP3
router router router router
PE5Profil PE3 PE4
4
Networks-on-Chip
• All the benefits are provided at the cost of router area, power consumption, data packetization and de-packetization.
•Cache coherence is the big issue.
router router router
router router router
router router router
router router router
DSP Mem
PE0
Mem
PE1 PE2
UP
ACC CoP Arb
Ctrl Mng
router
router
router
router
FPU
ALU
MPEG
MP3
router router router router
PE5Profil PE3 PE4
5
Networks-on-Chip
• Typical NoC
router router router
router router router
router router router
router router router
DSP Mem
PE0
Mem
PE1 PE2
UP
ACC CoP Arb
Ctrl Mng
• Comprises:
• Interconnects• Routers• Processing Elements
6
Networks-on-Chip
• Typical NoC• Key challenge:
• Flow control• Store and forword• Cut through
• Less buffer requirements
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Cycle
Chann
el H B B B T
H B B B TH B B B T
0123
Time-Space diagramsH B B B T
H B B B TH B B B T
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Cycle
Chann
el 0
123
Chann
el H B B B T
H B B B TH B B B T
0123
7
Networks-on-Chip
• Typical NoC• Key challenge:
• Flow control• Store and forword• Cut through
DEADLOCK!!!All channels are free.
IP3Interface
IP2
InterfaceIP1
(HM)
Interface
8
Networks-on-Chip
• Typical NoC• Key challenge:
• Flow control• Store and forword• Cut through
• Overall higher throughput but problem for time critical applications.• Good mapping/placement technique needed.
9
Networks-on-Chip
• Typical NoC• Target:
• Minimization of communication cost.•In terms of hop-count.
• Average hop-count should be one (Best case).• Inturn, power optimization.
• Mapping Criteria:• Cores communicating more often should be neighbors.
• Neighboring cores might not serve, when needed.• High piriority core/process should be mapped to highly suitable position. Piriority? Suitable position?
10
Core Prioritization
• Core Piriority:•Total number of packets to be communicated to-and-by the core. (Npi)•Number of neighboring cores required. (Ni)•Traffic distribution σxi
2 (statistical varience):•Number of neighbors of neighboring cores. (Nf)
2xiiPi
iNN
P
11
Placement Algorithm
12
Sample Application
• Priority:
MC > YUV Generator > ME > SRAM > DCT > Predictor > Q . . .
13
Sample Application
• Placement
14
Experimental Results
15
Future Work
•Extension to 3D NoCs•Cosideration of TSV features
THANKS!
16