Praveen Vishakantaiah, President of Intel India, discussed the challenges of validating next generation CPUs. Validation is increasingly complex due to factors like rising design complexity from multi-core processors and chipset integration, as well as shorter time to market windows. Validation efforts are also not scaling incrementally with post-silicon development. Addressing these challenges requires experienced architects and validators working closely together, instrumentation of design models to enable validation, reuse of validation tools, and scaling of emulation and formal verification techniques. Validation is critical to meeting customer satisfaction and business goals around schedule and costs.

1. Validating next generation CPUs
Praveen Vishakantaiah
President, Intel India
Feb 22, 2008
DV Club Bangalore

2. “Validation is increasingly in the critical path of product
success and requires continuous innovation to meet
customer satisfaction, schedule and margin
requirements”
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3. Agenda
• Current Challenges
• Addressing the challenges
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4. CPU bug trends
Exponential growth of design complexity
• Deeply pipelined complex micro-architecture
• Logic bugs increase 3 - 4x per generation
Pre-silicon logic bugs per generation 25000
( Source: Tom Schubert, Intel, DAC 2003 )
7855
800 2240
Pentium Pentium Pro Pentium 4 Next ?
Up to 70% of design time and resources are spent during
Up to 70% of design time and resources are spent during
functional validation
functional validation
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5. The Pre-Si Verification gap
EE Times 2004
EE Times 03/18/2004
Verification Capabilities is fast becoming the limiting
Verification Capabilities is fast becoming the limiting
5 factor for VLSI design improvements
factor for VLSI design improvements

6. Current Challenges – Technical
• Increasing CPU design complexity
– Multi core
– Chipset integration
– Power Management
– New technology like security
• Increasingly bulky validation environment
– Increase in development and maintenance cost
– Environment bugs >= Logic design bugs
• Increasing number of product variants
– Validation is not as incremental as design
• Increasing micro-architectural coverage space increases probability of escapes
• Decreasing simulation/emulation speed limits pre-silicon cycles
• Legacy features and compatibility validation
High volumes magnify the cost of a
High volumes magnify the cost of a
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validation escape – can not let it happen!
validation escape – can not let it happen!

7. Current Challenges – Non-Technical
• Shorter TTM (Time to Market)
• Physical limits and cost of data centers
• CPU validation expertise
– More pronounced in India due to frequent job changes
• Cross site development
– Design and validation may not be co-located
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8. Post-silicon validation
• SOC and Multi core leverage incremental design effort
– Design interactions are spatial in nature
– Effective design reuse is possible
• Post Si Validation efforts currently not scaling incrementally
- Logic interactions across widely separated areas introduces
unexpected bugs
- No effective coverage feedback mechanism
- When is Validation enough ?
- Synthesis of approx coverage measure
- Effective Mathematical Models
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9. Addressing the challenges
• Use experienced architects, micro-architects and front end designers
– Very likely to have lot more validation “burn” marks and will proactively code less bugs
– Will be able to help validators debug issues faster
– Raise the watermark for bugs and reduce iterations
• Validators drive requirements into architecture and micro-architecture
– Influence technology decisions to keep validation tractable
– Minimize feature creep during execution
– Reduce back end design impact on front end design
• Instrument design models to enable validation
– Assertions, instrumentation signals, comments
– Aim for sweet spot with Effectiveness vs. Efficiency trade offs
• Validation Environment
– Minimize custom tool development
• Reuse design, validation and debug tools across programs
• Scale emulation, formal verification and mixed signal validation
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10. Validation coverage profile and Efficacy
•Efficiency: Catch bugs fast
•Effectiveness: Catch all customer visible bugs
Probability of bugs
Si Spin1 Si Spin2 Time
Early detection and bug acceleration
Early detection and bug acceleration
10 has significant business benefits
has significant business benefits

11. Q&A
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