Energy-Efficient Time-Division Multiplexed Hybrid-Switched NoC for Heterogeneous Multicore Systems Jieming Yin * , Pingqiang Zhou + , Sachin S. Sapatnekar * and Antonia Zhai * * University of Minnesota, Twin Cities, USA + ShanghaiTech University, China 28 th IEEE International Parallel & Distributed Processing Symposium
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Jieming Yin * , Pingqiang Zhou + , Sachin S. Sapatnekar * and Antonia Zhai *
Energy-Efficient Time-Division Multiplexed Hybrid-Switched NoC for Heterogeneous Multicore Systems. Jieming Yin * , Pingqiang Zhou + , Sachin S. Sapatnekar * and Antonia Zhai *. * University of Minnesota, Twin Cities, USA + ShanghaiTech University, China. - PowerPoint PPT Presentation
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How can Packet and Circuit Switching share the same fabric?
ShanghaiTech
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SDM
A
B
C
D
4 bits
2 bits1 bits1 bits
Space-Division Multiplexing
A
B
C
D
A
B
C
D
(Space-divisionMultiplexing)
PS+CS
Physically divide a channel into sub-channels
• K. Lusala et al., IJRC 2012• S. Secchi et al., DSD 2008• A. K. Lusala, ReCoSoC 2011• M. Modarressi et al., DATE 2009SDM suffers from packet serialization problem
• Set up the path before transmission• Setup messages are sent through the packet-switched network• Acknowledge the source upon successful setupKeep time-slot assignment in Slot Tables
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0000
in_1
0
0
0
0
in_2
s0
s1
s2
s3
0
0
1 out_4
1 out_4
in_1
0
0
0
0
in_2
s0
s1
s2
s3
0
0
1 out_4
1 out_4
in_1
0
0
0
0
in_2
s0
s1
s2
s3
0
0
0 out_4
0 out_4
in_1
0
0
0
0
in_2
s0
s1
s2
s3
setup 1(succeed)
in_1 → out_4slot_id = 2
duration = 2
setup 2(fail)
in_1 → out_3slot_id = 3
duration = 1
teardown 1
in_1 → out_4slot_id = 2
duration = 2
① ②
③ ④
v out v out v out v out
v out v outv out v out
Slot Table Configuration Walkthrough
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Slot Table Size
Smaller slot table• Less energy overhead• Smaller packet waiting time• Coarser-grain multiplexing
Larger slot table• More energy overhead• Longer packet waiting time• Finer-grain multiplexing
Initial (reset)
more request
more request
(reset)
Slot table
V.S.
Slot table size should be adjusted dynamically
active
inactive
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Circuit-Switched Path ExclusivenessSlot Table
s0s1s2s3s4s5s6s7
11011011
v out
out_3out_3(PS)
out_2out_2(PS)
out_1out_1
Crossbar
SW Allocator
• Crossbar must be configured before a circuit-switched flit’s arrival. Time slot is wasted if circuit-switched flit is not presented.
configuration signals
Exclusively occupied by
circuit-switched paths
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Time-slot Stealing
SW Allocator
Crossbar
v out
Dec
oderLine Address
valid
Slot Table
VC Allocator
configurationsignals
CS flit enable
From upstream routerEnable path reuse between packet- and circuit-switched data paths
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Routing decision is made based on the utilization of slot tables in neighbor routers