1. Processor Design Challenges
Vojin G. Oklobdzija
University of California / Integration
ISSCC Microprocessor Design Workshop 2001
Thursday, Feb 8th, 2001, San Francisco, CA

2. Processor Design Challenges
Will technology be able to keep up ?
Will the bandwidth keep up ?
Will the power be manageable ?
Can we deliver the power ?
What will we do with all those transistors ?
April 4, 2019
V. G. Oklobdzija, Integration Corp.

3. CMOS Performance Roadmap
Source : B. Davari, Symp. VLSI Circuits, 1999
April 4, 2019
V. G. Oklobdzija, Integration Corp.

4. V. G. Oklobdzija, Integration Corp.
April 4, 2019
V. G. Oklobdzija, Integration Corp.

5. V. G. Oklobdzija, Integration Corp.
Performance
3X / generation
Source:
ISSCC, uP Report, Hot-Chips
April 4, 2019
V. G. Oklobdzija, Integration Corp.

6. V. G. Oklobdzija, Integration Corp.
Total transistors
3X / generation
Logic transistors
2X / generation
Source:
ISSCC, uP Report, Hot-Chips
Source:
ISSCC, uP Report, Hot-Chips
April 4, 2019
V. G. Oklobdzija, Integration Corp.

7. Processor Design Challenges
Performance seems to be tracking frequency increase
Where are the transistors being used ?
3X per generation growth in transistors seems to be uncompensated as far as performance is concerned
April 4, 2019
V. G. Oklobdzija, Integration Corp.

8. Well, it will make up in power …
100
x4 / 3years 10
Power (W) 1
0.1
0.01 80 85 90 95
Courtesy of Sakurai Sensei
April 4, 2019
V. G. Oklobdzija, Integration Corp.

9. Gloom and Doom predictions
Source: Shekhar Borkar, Intel
April 4, 2019
V. G. Oklobdzija, Integration Corp.

10. V. G. Oklobdzija, Integration Corp.
Power versus Year
High-end growing at 25% / year
12% / yr
15% / yr
Consumer (low-end)
At 13% / year
April 4, 2019
V. G. Oklobdzija, Integration Corp.

11. V. G. Oklobdzija, Integration Corp.
Energy-Delay product is improving more than 2x / generation
Saving Grace !
April 4, 2019
V. G. Oklobdzija, Integration Corp.

12. V. G. Oklobdzija, Integration Corp.
X86 efficiency improving dramatically
4X / generation
average improving
3X / generation
High-End processors efficiency not improving
April 4, 2019
V. G. Oklobdzija, Integration Corp.

13. Power Delivery Problem (not just California)
Your car
starter !
Source: Shekhar Borkar, Intel
April 4, 2019
V. G. Oklobdzija, Integration Corp.

14. V. G. Oklobdzija, Integration Corp.
Trend in L di/dt:
di/dt is roughly proportional to
I * f, where I is the chip’s current and f is the clock frequency
or I * Vdd * f / Vdd = P * f / Vdd, where P is the chip’s power.
The trend is:
P f Vdd
on-chip L package L slightly decreases
Therefore, L di/dt fluctuation increases significantly.
Source: Shen Lin, Hewlett Packard Labs
April 4, 2019
V. G. Oklobdzija, Integration Corp.

15. What to do with all those transistors ?
We have reached 170 Million
We will reach 1 Billion in the next 5 years !
Memory transistors will save us from power crisis
What should the architecture look like ?
April 4, 2019
V. G. Oklobdzija, Integration Corp.

16. What Drives the Architecture ?
Processor to memory speed gap continues to widen
Transistor densities continue to increase
Application fine-grain parallelism is limited
Time and resources required for more complex designs is increasing
Time-to-market is as critical as ever
Multiprocessing on the Chip ?
April 4, 2019
V. G. Oklobdzija, Integration Corp.

17. V. G. Oklobdzija, Integration Corp.
ccNUMA Design
Source: Pete Bannon, DEC
Metrics
Topologies
Cache Coherence C4 M4 IO C5 M5 C0 M0 C7 M7 C6 M6
X bar or Network C1 M1 C2 M2 C3 M3
April 4, 2019
V. G. Oklobdzija, Integration Corp.

18. How can we survive the challenges ?
Advances in Technology and Circuits (SOI)
Advances in High-Performance I/O
Advances in Power Management and Delivery
New Trends in Chip Architecture
April 4, 2019
V. G. Oklobdzija, Integration Corp.