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Reiner Pope – Chip design from the bottom up

Dwarkesh Podcast

Shownote

New blackboard lecture with Reiner Pope: how do chips actually work - starting with basic logic gates, and working up to why GPUs, TPUs, FPGAs, and the human brain each look the way they do. Reiner [https://reiner.org/] is CEO of MatX [https://matx.com/], a new chip startup (full disclosure - I’m an angel investor). He was previously at Google, where he worked on software [https://arxiv.org/abs/2211.05102] efficiency [https://jax-ml.github.io/scaling-book/], compilers, and TPU architecture. Watch this one on YouTube [https://youtu.be/oIk3R-sMX5o] so you can see the chalkboard. Read the transcript [https://www.dwarkesh.com/p/reiner-pope-2]. Sponsors * Crusoe [https://crusoe.ai/dwarkesh] was one of only five GPU clouds that made the gold tier in SemiAnalysis' most recent ClusterMAX report. Gold-tier providers like Crusoe delivered 5-15% lower TCO than silver-tier clouds, even with identical GPU pricing. This is because optimizations like early fault detection and rapid node replacement don't necessarily show up in the sticker price, but still matter a ton in the real world. Learn more at crusoe.ai/dwarkesh [https://crusoe.ai/dwarkesh] * Cursor [https://cursor.com/dwarkesh] is where I do most of my work—from reading research papers to visualizing technical concepts to coding up internal tools for the podcast. Most recently, I used it to build two different review interfaces for my essay contest, one that anonymizes submissions for scoring and another that lets me see applicants' essays next to their resumes and websites. Whatever you're working on, you should try doing it in Cursor. Get started at cursor.com/dwarkesh [https://cursor.com/dwarkesh] * Jane Street [https://janestreet.com/dwarkesh] let me ask Ron Minsky and Dan Pontecorvo, two senior Jane Streeters, a bunch of questions about how they use AI. We discussed everything from the types of models they're training to how they think about the future of trading to why they're more bullish than ever on hiring technical talent. You can watch the full conversation and learn more about their open positions at janestreet.com/dwarkesh [https://janestreet.com/dwarkesh] Timestamps 00:00:00 – Building a multiply-accumulate from logic gates 00:16:31 – Muxes and the cost of data movement 00:26:10 – How systolic arrays work 00:39:11 – Clock cycles and pipeline registers 00:51:51 – FPGAs vs ASICs 01:03:25 – Cache vs scratchpad 01:07:27 – Why CPU cores are much bigger than GPU cores 01:12:00 – Brains vs chips 01:15:33 – A GPU is just a bunch of tiny TPUs Get full access to Dwarkesh Podcast at www.dwarkesh.com/subscribe [https://www.dwarkesh.com/subscribe?utm_medium=podcast&utm_campaign=CTA_4]

Highlights

This podcast features a detailed technical discussion on how computer chips, from basic logic gates to advanced AI accelerators, are designed and how they function. The conversation explores the fundamental trade-offs in chip architecture, focusing on the balance between computation and data movement, and compares different processor types including CPUs, GPUs, TPUs, and FPGAs.
09:54
Multiply-accumulate is the core primitive in AI chips.
22:39
Register file costs motivated the shift to tensor cores.
26:10
Quadratic compute growth with only linear communication costs.
48:23
Adding pipeline registers increases clock speed but consumes area
1:01:25
FPGAs are 10x slower than ASICs.
1:03:32
Deterministic latency is possible in CPUs but avoided for market reasons.
1:10:47
Branch prediction enables high clock speeds
1:12:05
Slowing a chip to MHz reduces energy linearly but not 1000x due to idle circuits.
1:18:54
GPUs have higher data movement bandwidth than TPUs

Chapters

Building a multiply-accumulate from logic gates
00:00
Muxes and the cost of data movement
16:31
How systolic arrays work
26:10
Clock cycles and pipeline registers
39:11
FPGAs vs ASICs
51:51
Cache vs scratchpad
1:03:25
Why CPU cores are much bigger than GPU cores
1:07:27
Brains vs chips
1:12:00
A GPU is just a bunch of tiny TPUs
1:15:33

Transcript

Dwarkesh Patel: I'm back with Reiner Pope, who is the CEO of MatX, which is a new AI chip company. Last time we were talking about what happens inside a data center. Now I understand what happens inside an AI chip. How does a chip actually work? Full discl...