University of Michigan Electrical Engineering and Computer Science From SODA to Scotch: The Evolution of a Wireless Baseband Processor Mark Woh (University of Michigan - Ann Arbor) Yuan Lin (University of Michigan - Ann Arbor) Sangwon Seo (University of Michigan - Ann Arbor) Scott Mahlke (University of Michigan - Ann Arbor) Trevor Mudge (University of Michigan - Ann Arbor) Chaitali Chakrabarti (Arizona State University) Richard Bruce (ARM Ltd.) Danny Kershaw (ARM Ltd.) Alastair Reid (ARM Ltd.) Mladen Wilder (ARM Ltd.) Krisztian Flautner (ARM Ltd.)
Transcript
University of MichiganElectrical Engineering and Computer Science
From SODA to Scotch: The Evolution of a Wireless Baseband Processor
Mark Woh (University of Michigan - Ann Arbor)Yuan Lin (University of Michigan - Ann Arbor)Sangwon Seo (University of Michigan - Ann Arbor)Scott Mahlke (University of Michigan - Ann Arbor)Trevor Mudge (University of Michigan - Ann Arbor)Chaitali Chakrabarti (Arizona State University)Richard Bruce (ARM Ltd.)Danny Kershaw (ARM Ltd.)Alastair Reid (ARM Ltd.)Mladen Wilder (ARM Ltd.)Krisztian Flautner (ARM Ltd.)
2University of Michigan
Electrical Engineering and Computer Science
From SODA to Scotch : What is this talk about?
• If a fully programmable 3G baseband processor commercially viable?
► The SODA processor was the first full research design [ISCA06]
► ARM R&D developed the Ardbeg SDR commercial prototype
• What we will present► Comparison study between SODA and Ardbeg► Lessons learned in the evolution
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Mobile Computing
• In 2007, world-wide mobile telephone subscription: 3.3 billion1
► ~Half of the world’s population► Some countries have mobile penetration over 100%► Largest consumer electronic device in terms of volume
3 Read/2 Write RF for VLIW3 Read/2 Write RF for VLIW
Sparse Connected VLIWSparse Connected VLIW
Multiple Data Address AccessesMultiple Data Address Accesses
Fused Permute ALU operationsFused Permute ALU operations
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Electrical Engineering and Computer Science
Evolution to Ardbeg : Lessons Learned
• Ardbeg achieved ~3x speedup overall at 30% lower power than SODA
• To get these improvements many lessons were learned as a result of the studies done
• We will present a few of these studies► 1) Benefit of Wide SIMD► 2) VLIW on SIMD support► 3) Support for Complex Shuffle Network ► 4) Application Specific Hardware
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1) Benefiting from Wide SIMD
• Increasing SIMD width still a good idea for SDR• But area becomes a big concern
► 32 wide 16-bit SIMD at 90nm seems a good fit
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SIMD Width
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rma
lize
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Electrical Engineering and Computer Science
2) VLIW Support for Wide SIMD
• VLIW execution on top of the SIMD datapath
• 3 read ports, 2 write ports
► Shared between SIMD units► 2-issue SIMD LIW► Only support the most
frequently used SIMD op pairs
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SIMD
32-lane
SIMDALU
32-lane
SIMDALU
SIMDRF
SIMDRF
128-laneSSN
128-laneSSN
SIMDscalartrans.unit
SIMDscalartrans.unit
EXEX
WB
WB
scalarRF
scalarRF
16-bitALU
16-bitALU
EXEX
WB
WB
InterconnectsInterconnects
EXEX
WB
WB
InterconnectsInterconnects
EXEX
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Scalar
AGUAGU
DataMEMDataMEM
AGUAGU
AGUAGU
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Electrical Engineering and Computer Science
2) VLIW on SIMD Support
• There is a distinct set of instructions that execute frequently at the same time
• We want to take advantage of this in order to reduce complexity of VLIW
Mem.Arith.Mult.
ShuffleTrans.Move
Comp.
Mem.
NAHighHighLowHighLowLow
Arith.
--NAMidHighMidLowLow
Mult.
----
NAMidHighHighLow
Shuffle
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NAMidLowLow
Trans.
--------
NALowLow
Move
----------
NALow
Comp.
------------
NA
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Electrical Engineering and Computer Science
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FIR CFIR FFT Radix-2 FFT Radix-4 Viterbi K7 Viterbi K9 Average
