9th International SoC Conference 2011 FUSION APU & TRENDS/ CHALLENGES IN FUTURE SoC DESIGN

1. FUSION APU AND TRENDS/
CHALLENGES IN FUTURE
SOC (PROCESSOR) DESIGN
Pankaj Singh,
Acknowledgement:
Denis Foley. Sr. Fellow, AMD
9th International SoC Conference
2nd & 3rd November 2011

2. 2 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
TODAY’S TOPICS
 Trends:
– Three Eras of Processor Performance
– Evolution of Heterogeneous Computing
 FSA and Open Standard:
– Why Fusion ?
– Open Standard, Open CL
 Power, Performance
 High Speed, Scalable Interconnect: NoC’s
 3-D Stacking
 SoC Trends & Challenges
– Verification Effort
– IP Integration
– TLM, RTL Co-simulation challenges.

3. 3 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
TRENDS: THREE ERAS OF PROCESSOR PERFORMANCE
Single-Core
Era
Single-threadPerformance
?
Time
we are
here
o
Enabled by:
 Moore’s Law
 Voltage Scaling
 MicroArchitecture
Constrained by:
Power
Complexity
Multi-Core
Era
ThroughputPerformance
Time
(# of Processors)
we are
here
o
Enabled by:
 Moore’s Law
 Desire for Throughput
 20 years of SMP arch
Constrained by:
Power
Parallel SW availability
Scalability
Heterogeneous
Systems Era
TargetedApplication
Performance
Time
(Data-parallel exploitation)
we are
here
o
Enabled by:
 Moore’s Law
 Abundant data parallelism
 Power efficient GPUs
Currently constrained by:
Programming models
Communication overheads

4. 4 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
TRENDS: EVOLUTION OF HETEROGENEOUS COMPUTINGArchitectureMaturity&ProgrammerAccessibility
PoorExcellent
2012 - 20202009 - 20112002 - 2008
Graphics & Proprietary
Driver-based APIs
Proprietary Drivers Era
 “Adventurous” programmers
 Exploit early programmable
“shader cores” in the GPU
 Make your program look like
“graphics” to the GPU
 CUDA™, Brook+, etc
OpenCL™, DirectCompute
Driver-based APIs
Standards Drivers Era
 Expert programmers
 C and C++ subsets
 Compute centric APIs , data
types
 Multiple address spaces with
explicit data movement
 Specialized work queue based
structures
 Kernel mode dispatch
Fusion™ System Architecture
GPU Peer Processor
Architected Era
 Mainstream programmers
 Full C++
 GPU as a co-processor
 Unified coherent address space
 Task parallel runtimes
 Nested Data Parallel programs
 User mode dispatch
 Pre-emption and context
switching
More uptodate information on FSA:
http://developer.amd.com/afds/pages/keynote.aspx#/Dev_AFDS_Reb_2

5. 5 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
FSA & OPEN STANDARD: ENTER FUSION
Dual Core CPU Northbridge DirectX®11 GPU
FUSION APU
(Accelerated Processing Unit)
Heterogeneous compute engine combining
x86 compute and parallel processing
capabilities of the GPU on a single die

6. 6 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
FSA & OPEN STANDARD: WHY FUSION?
6
 Integrating CPUs, Northbridge and GPU enables:
– Unified Memory
– High-bandwidth, low latency access by GPU
– Saves on interface power and PHY area
– Shared Power Control and TDP envelope
Potential bandwidth bottleneck
Relatively long memory latency

7. 7 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
COMMITTED TO OPEN STANDARDS
 AMD drives open and de-facto
standards
– Compete on the best
implementation
 Open standards are the basis for
large ecosystems
 Open standards always win over
time
– SW developers want their
applications to run on multiple
platforms from multiple
hardware vendors
DirectX®

8. 8 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
OPENCL™ AND FSA
 FSA is an optimized platform
architecture for OpenCL™
– Not an alternative to OpenCL™
 OpenCL™ on FSA will benefit from
– Avoidance of wasteful copies
– Low latency dispatch
– Improved memory model
– Shared pointers
 FSA also exposes a lower level
programming interface, for those
that want the ultimate in control
and performance
 Optimized libraries may choose
the lower level interface

9. POWER & PERFORMANCE

10. 10 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
POWER-THERMAL EFFECTS IN SYSTEMS ON CHIPS
¡ Local failures !
Part not working
 Complex SoCs: High power density
 Non-uniform power dissipation: Hotspots
 Spatial gradients: Cause malfunctions
 High on-chip temperatures cause
malfunctions affecting reliability.
 Power consumption depends on
frequency
 Setting frequencies to control power and
temperature

11. 11 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
OPTIONS FOR POWER SAVINGS
 Convergence of Performance and Low Power
– Notebook->Netbook-> Tablet
Tablet<-Smartphone

12. 12 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
PERFORMANCE AND POWER
S3 idle Static
Screen
MM07 Media
Playback
Full
Compute
APU Power vs. Use Case
Performance
Power
 Performance versus Power Efficiency
 Power Management versus Power reduction
 Performance & Thermal Design Power

13. HIGH SPEED, SCALABLE
INTERCONNECT

14. 14 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
NOC’S: FROM BUSES TO NETWORKS:
[Friedman Harel:10]
Note: This slide presents industry specific information does not relate to AMD NoC status

15. 15 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
NOC CHALLENGES: CAD TOOLS
 Capturing application traffic.
 Which Topology ?
 Mapping? Routes to use?
 Fixing communication
architecture : parameters.
 Verification for correctness, performance.
 Build models.
 QoS under un-reliable conditions.
Key to success: Automate & integrate the steps.
Mesh Topology
homogeneous systems, with
regular tiles
Customized Topology
heterogeneous systems, with
different cores & irregular FP
Software Services
Mapping, QoS, middleware...
Architecture
Packeting, buffering, flow control...
Physical Implementation
Synchronization, wires, power...
CAD Tools

16. 16 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
Synchronous Delay Insensitive
Global None
Timing Assumptions
Less Detection
Local Clocks, Interaction
with data (becoming aperiodic)
 A complete spectrum of approaches to system-timing exist
[Mullins06-07]
NOC CHALLENGES: BEYOND GLOBAL SYNCHRONY
Delay Insensitive

17. 3-D STACKING

18. 18 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
3-D STACKING
 Supporting Heterogeneous computing: high density, high performance,
high memory B.W requirement.
 3-D NoC’s option
 Futuristic view:
Integrating Bio-sensor
Note:
This slide presents industry specific information does not relate to AMD 3-D stacking status

19. SOC TRENDS &
CHALLENGES:
1. VERIFICATION EFFORT
2. IP INTEGRATION
3. TLM-RTL CO-SIMULATION

20. 20 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
WHAT’S NEW IN SOC DESIGN?
 Larger and more complex chips with heavy use of pre-existing cores.
 Heavy use of multi core processors and DSPs.
 Complex Interconnect.
 Shorter time to market and Smaller design teams.
 … and software.
 Leads to:
– Increased verification effort: Debugging is harder.
– Integration is more difficult.
– Need for scalable and high speed interconnect.
– SW / HW co-simulation is a major issue.
– Power –Performance challenge.
– How do we treat the system software?

21. 21 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
VERIFICATION EFFORT
 Debugging
– Seamless debug across
h/w and software[especially SW]
 Testbench Development:
– Several methodologies
 VMM,OVMUVM.
 New developments
[Unified strategy]
– UCIS,UVM TLM2.0
– Coverage trend
 Address Gaps in VHDL,
System C coverage

22. 22 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
VERIFICATION EFFORT
 Creating/Running Testcase:
– Direct & Random
– Run time improvement
Save-restore.
Verification Cycle per second instead of Cycles per second:
Configuring environment to dynamically select relevant
design/core.
Alternate options

23. 23 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
Emulation Focus Areas:
1. Tests/regression run with Long run time
2. Corner case bugs that may escape traditional verification
3. Replicating System level scenarios
Ongoing Initiatives/Need:
1.Seemless support for assertions.
2.Improve portability between Simulation & Emulation
3. Common model from TLM-HDL-Emulation
VERIFICATION EFFORT
 Alternate Options

24. 24 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
IP INTEGRATION CHALLENGE
 Integration of IP :
– Multiple IP’s, various configurations, design languages
– IP’s to be in Sync: macro’s , libraries.
– Complexity increases with mixed language designs
SYSTEM
C
SVLO
G
VERILOG
VHDL
Unique Strengths
of Languages
Diversity of Design
Teams
Importing Existing
IP
Legacy Testbench
Environment

25. 25 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
IP INTEGRATION CHALLENGE COMPARISON OF CHOICES
Direct
Instantiation
SV Bind
Construct
SystemC
Control/Observe
SCV-
Connect()
SC-DPI
Source Code
Available
Yes Yes Yes Yes Yes
One IP
Compiled
Yes Yes Yes Yes Yes
Both IP
Compiled
No Yes No No No
Performance ++++ (3) +++ (2) + (1) + (1) +++++(4)
Delta Delay Yes Yes No No No
Languages
Supported
SV, SC,
VHDL
SV, SC,
VHDL
SC + SV/VHDL
SC +
SV/VHDL
SC + SV
Gap: No standardized automated methodology for integration.
Recommended Approach:
• Understand IP blocks: language, source code availability.
• Understand connection: 1-1, distributed, method port
• Option for optimized solution to quickly build a system

26. 26 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
IP INTEGRATION CHALLENGE: GAPS WITH ANALOG IP
INTEGRATION IN SOC
Table1. Gaps with Analog IP Integration in SoC
Gaps Root Cause
Testchip setup
-Testchip scenario is different
-Tester used for testchip differs
Inbuilt debug
-Incomplete inbuilt SoC test/debug capability or derisk option for basic
functionality such as PLL clock
IP I/F verification -Incomplete test setup
Review process
-No common detailed review process between IP and SoC team. Incorrect
assumption based on past analog IP working silicon
IP Modelling
-Mismtach in version between IP simulation model and spice netlist
-Limitations of behavioral model to replicate actual analog IP functionality
-Timing issue
-DFT issue
EDA tools -Gaps in analog and digital simulation environment

27. 27 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
 Verification Environment Bring-up
– Automated Assertions for early checks.
– Review forces, tie-off and relevant checkers from IP to SoC
– Bottleneck for SoC team to get started with verification: Option to use
fake model for initial bring up. Usage of system model.
– Super Block Concept: pre-verified IP blocks at similar frequency &
interface
 Requirement:
 Current solution: In-house methodology and process. No clear solution
from EDA vendors.
IP INTEGRATION CHALLENGE
IP
Block1
IP
Block2
Minimum
Manual
Effort
Hookup
Using ICU
No BUGS!

28. 28 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
TLM, RTL Co-simulation
 Traditional use of System level models : Architecture profiling &
Performance Analysis
 Increasing Demand for Co-simulation: Tradeoff between Accuracy and
Performance.
 Open Challenges
 Different level of Abstraction.
 Need for improvement in Integration methodology and Test bench
development
 Seamless Debug and Coverage methodology.
 Using System Level model for HDL generation
 Legacy system model not written with conversion in mind.
 Current limitation: Incomplete translation.
 Lack of reliable Equivalence Check tool.
 Need: Merge top down (SystemC) and bottom-up (System Verilog)
methodology/flow.
 Gaps/Work to do: How to do Power analysis

29. 29 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
THANK YOU!

30. 30 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
REFERENCES
[1] Wilson Research Group-MGC study blog 2011.
[2] AMD Coolchip2011 presentation. Denis Foley, AMD Sr. Fellow.
[3] Fusion Processors and HPC-2011, Chuck Moore, AMD Corporate
Fellow & Technology Group CTO
[3] AMD Fusion Developer Summit 2011. Phil Rogers, AMD Corporate
Fellow
[4] Fully Asynchronous framework for GALS network on chip. Friedman H
[5]Future of EE, NoC’s presentation. Dr. Srinivasan Murali
[6] Analog IP integration in SoC, IP reuse’09. Mixed language IP integration
DVCoN 2010. Extending Fucntional coverage to SystemC, VHDL-IP’10.
Pankaj S

31. 31 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
GLOSSARY
 GPU – Graphics processing unit
 APU: Accelerated Processing Unit
 Open CL: Open Computing Language
 TDP – Thermal Design power – a measure of a design
infrastructure’s ability to cool a device
 NoC: Network On Chip
 TLM: Transaction Level Modeling
 Turbo Core – AMD boost mechanism
 QoS: Quality of Service
 UVM: Universal Verification Methodology
 UCIS: Unified Coverage Interoperability Standard

32. 32 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
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33. 33 | 9th Intl. SoC Conference| Nov 2nd,3rd, 2011
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