An interview with AMD's Mike Clark, the Father of Zen — 'Zen Daddy'

[erek]

“Intel has famously abandoned injecting hardware acceleration support for high-performance AVX-512 instructions, but AMD's Zen 5 marks the debut of full AVX-512 acceleration for the Ryzen family. Unlike Intel, which has to reduce clock speeds when its processors run AVX-512 workloads, AMD says these powerful instructions will run at the same clock speeds as standard integer operations. Clark also expanded on how the company achieved that feat and said that its Zen 5c cores can also run full AVX-512.


Below is a lightly edited transcript of the key points of our conversation with Clark.”

Source: https://www.tomshardware.com/pc-com...ast-3nm-launch-zen-5c-cores-for-desktop-chips

 

[Elf_Boy]

Why does Intel need to downclock for AVX-512?

Does that add all sorts of logic, with an am I doing this check before every instruction? Wouldn't that really slow things down?

Dont really know much about the insides of CPU's and am curious.

 

[toast0]

Why does Intel need to downclock for AVX-512?

Does that add all sorts of logic, with an am I doing this check before every instruction? Wouldn't that really slow things down?

Historically, Intel downclocked for avx-512 because a sustained stream of avx-512 instructions uses a lot more of the chip than a normal instruction stream, and resulted in unsustainable power/heat/etc.

As I understand it, there's some sort of flag for used avx in the last while, that the clock setting logic uses. So if you do one avx instruction, the clock gets lowered for a while. That lead people to try to only use avx if they have a sustained load. But I don't keep up to date on this... that's probably several generations old; I think newer Intel chips with avx-512 are supposed to be better.

 

[Marees]

Another interview with Mike Clark. A very technical one

https://chipsandcheese.com/2024/07/...ith-mike-clark-chief-architect-of-zen-at-amd/

 

[Marees]

Apparently Clark is the father of zen & Jim Keller just one of the 'uncles'

https://forums.tomshardware.com/thr...mpact-cores-for-desktop.3850068/post-23305020

Mike Clark was the lead architect from day one. I was in the audience when he introduced Zen 1 at Hot Chips in 2016 as the lead architect. I even interviewed him backstage after the presentation. (Fun fact: I interviewed him in the same green room Steve Jobs used before his most famous presentations).

https://www.tomshardware.com/news/amd-zen-cpu-microarchitecture,32540.html

Keller, worked on the Infinity Fabric. He made contributions there, but was not the lead architect.

https://forums.tomshardware.com/thr...mpact-cores-for-desktop.3850068/post-23305023

Ian Cutress: A few people consider you 'The Father of Zen', do you think you’d scribe to that position? Or should that go to somebody else?

Jim Keller: Perhaps one of the uncles. There were a lot of really great people on Zen. There was a methodology team that was worldwide, the SoC team was partly in Austin and partly in India, the floating-point cache was done in Colorado, the core execution front end was in Austin, the Arm front end was in Sunnyvale, and we had good technical leaders. I was in daily communication for a while with Suzanne Plummer and Steve Hale, who kind of built the front end of the Zen core, and the Colorado team. It was really good people. Mike Clark's a great architect, so we had a lot of fun, and success. Success has a lot of authors - failure has one. So that was a success. Then some teams stepped up - we moved Excavator to the Boston team, where they took over finishing the design and the physical stuff, Harry Fair and his guys did a great job on that. So there were some fairly stressful organizational changes that we did, going through that. The team all came together, so I think there was a lot of camaraderie in it. So I won't claim to be the ‘father’ - I was brought in, you know, as the instigator and the chief nudge, but part architect part transformational leader. That was fun.

Source: https://www.anandtech.com/show/16762/an-anandtech-interview-with-jim-keller-laziest-person-at-tesla