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Some Limits of Power Delivery in the Multicore Era. Runjie Zhang , Brett H. Meyer, Wei Huang, Kevin Skadron and Mircea R. Stan University of Virginia, McGill University, IBM Austin Research Lab. ITRS Projection on Transistor Density (2011 Edition). Source: ITRS 2011. - PowerPoint PPT Presentation
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Some Limits of Power Delivery in the Multicore Era
Runjie Zhang, Brett H. Meyer, Wei Huang, Kevin Skadron and Mircea R. Stan
University of Virginia, McGill University,
IBM Austin Research Lab.
ITRS Projection on Transistor Density (2011 Edition)
2
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 20260
10000
20000
30000
40000
50000
60000
70000
80000
Year
Mtr
an
sist
ors
/cm
2
Source: ITRS 2011
Power Density and Current Density
3
45nm 32nm 22nm 16nm0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Power Density Current Density
Tech Node
W/m
m2
A/m
m2
Current = Power / Supply Voltage
The Chip - Package
4 Source: pcgameshardware.com
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The Chip – Inside the Package
Source: ITRS 2009Edition,
The Chip – C4 Bumps
Source: flipchips.com,Source: Wikipedia
What are the problems?
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2011
2013
2015
2017
2019
2021
2023
2025
2500
3000
3500
Year
Tota
l Pa
d C
ount
Source: ITRS 2011Edition,
3.7% 5.6% 7.4% 11.1%0%
50%
100%
150%
200%
250%
300%
IR drop
Maxim
um
Dela
y I
ncre
ase
Source: Shao et al. IEEE Computer Society Annual Symposium on VLSI, 2005
Source: Ye et al. Applied Physics letters, 2003
Electromigration
Architecture Level PDN Model
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• Input:– PDN physical parameters. E.g. metal width– Processor floorplan and powermap.– Pad configuration
• Output:– Voltage pad– Pad current
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Architecture Level PDN Model
Validation
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• IBM Power Grid analysis benchmarks– Steady-State– SPICE format– Provides details about metal layer and Pad
locations
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Power Map
VDD Pad Distribution
IBM_PG6
Validation Results
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Pad Current Comparison
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Multicore Scaling
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Baseline: 3.7GHz, Duo Core, Intel Penryn 4-way OoO Processor
Private L2 cache, 3MB per core
Mesh-Based NoC
45nm 32nm 22nm 16nm# of Cores 2 4 8 16Area(mm2) 116.4 124.8 131.5 149.3
Supply Voltage 1 0.9 0.8 0.7Peak Total Power (W) 74.62 100.5 116.8 148.5
Peak Total Current(A) 74.6 111.6 145.9 212.1
Flooplan
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Power Delivery Noise Scaling Trend
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Pad Optimization
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Sorted Pad Current After Optimization
Sorted Pad Current Before Optimization
I/O vs. Power Supply
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Const core-to-MC ratio
80 pads per MC
5% IR drop target
Thermal vs. Power Delivery
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Conclusions
• Power delivery is becoming a limiting factor in near future;
• IR drop poses a bigger challenge than ElectroMigration;
• Memory bandwidth will be affected’• With liquid cooling, scaling hit power
delivery wall before thermal wall.
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Questions?
22
Thanks!
23
Temerature Map vs. Voltage Map
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Voltage (V) Temperature(o C)
25
Volta
ge (V
)Te
mpera
ture
(oC
)
