Communications of the ACM

from 35 different countries. They have already accomplished amazing things, and they represent every school in the university, from law and business to engineering and the social sciences. Given the gigantic leadership problems that we have around the world, hopefully we can get a new generation of young people out there that are determined to do better.

John, you’re also writing a book about
leadership.

JOHN: It is at the publisher now. It’s a short book—it’s meant to be readable on a cross-country flight. It’s about my experiences with a variety of leadership issues and what I learned about it. The first chapter is humility.

Anything else?

DAVE: With the ending of Dennard Scaling and Moore’s Law, we must change the instruction set for major gains in cost, performance, energy, or security. Freeing architects from the chains of proprietary instruction sets may spur innovation like in the 1980s. Hence the title of our Turing Lecture: “A New Golden Age for Computer Architecture: Domain Specific Hardware/Soft-ware Co-Design, Enhanced Security, Open Instruction Sets, and Agile Chip Development.”

Leah Hoffmann is a technology writer based in Piermont, NY, USA.

kinds of functions that these machines need to do well.

DAVID: The reason that John and I are such good co-authors is that we have almost identical world views. Domain-specific architectures are in the newest chapter of our book, and for sure they’re an exciting development.

There are two other things I’m interested in. First is RISC-V, an open instruction set architecture that’s based on RISC principles. Not too many people get to work on proprietary instruction sets like ARM and x86, but everybody can get involved in the instruction set evolution of RISC-V. The other thing is getting better at security. So far, we haven’t asked much of computer hardware in security. I think architects need to step up and really help attack this problem. What’s exciting about the RISC-V is that you can download a full viable software stack, prototype your idea using an FPGA, stick it on the Internet, let people attack it, and see whether or not it works. The iteration loop can be days instead of the years it takes with proprietary instruction sets.

John, you’re also involved with the Knight-Hennessy Scholars Program, which aims to “build a multidisciplinary community of Stanford graduate students dedicated to finding creative solutions to the world’s greatest challenges.”

JOHN: We just admitted our first class coming this fall. We have 49 students

all smartphones and mobile devices.

JOHN: The key thing to understand is the efficiency issue. When Dave and I were developing RISC architectures, we had to find efficient ways to use the silicon that was available at the time to get the highest-performance machines. Today, you’re constrained by a whole set of different factors. Sometimes it’s a question of the silicon area, because you’ve got to be able to sell processors for a dollar. But the other big constraint is energy efficiency, because so many things are battery powered, or you can’t include a fan to cool them. So the RISC’s underlying efficiency has enabled it to catapult into this critical role.

DAVID: It’s kind of like “Back to The Future.” When they’re selling things for pennies, people care a lot about the number of transistors they use. At the very high end, the instruction set matters less because there are so many other things going on. At the low end, you even worry about how many registers you have. What’s nice about RISC is that it works fine at the high end, and it’s a big asset at the low end, and that’s why it’s been so successful.

What excites you both in the field of
computer architecture?

JOHN: As conventional uniprocessors stall out, there’s a focus now on what Dave and I have called domain-specific architectures—architectures that are designed for specific classes of problems. The obvious example now is deep neural networks; they use very specific computing strategies, and you can get an order of magnitude in efficiency by designing an architecture that does the