CS249r Notes: What We Learned

Weekly recaps and reflections from Harvard’s CS249r: Architecture 2.0


Week 6: Can AI Co-Design Distributed Systems? Scaling from 1 GPU to 1,000

October 08, 2024 • Software, systems • 24 min read

Let’s imagine the following (quite realistic) scenario: You’ve learned how AI can optimize CPU code. You’ve seen AI generate blazingly fast GPU kernels. Your single machine performance is perfect. Now you need to scale to 1,000 GPUs to train your frontier model. Or maybe 200,000 GPUs, like xAI’s Colossus supercomputer,...

Read More →

Week 5: Can LLMs Optimize GPU Performance? From CPU Transparency to GPU Complexity

October 01, 2024 • Software, performance • 24 min read

Over the past four weeks, we’ve been exploring a central question: can AI systems help us optimize performance at scale? We started with the foundational challenges of Architecture 2.0, examined the software engineering reality gap between AI capabilities and real development tasks, and investigated how Google’s ECO system tackles CPU...

Read More →

Week 4: Can AI Optimize Production Code? From Contest Winners to Google's ECO

September 24, 2024 • Software • 29 min read

On September 12, 2024, AI models demonstrated stunning capabilities at the International Collegiate Programming Contest (ICPC). OpenAI’s GPT-5 managed to achieve a perfect score, answering 12 out of 12 problems, a performance akin to winning a gold medal. Not to be outdone, Google’s Gemini 2.5 Deep Think solved 10 of...

Read More →

Week 3: Can AI Really Replace Software Engineers? The Reality Behind Contest-Winning Code

September 17, 2024 • Software • 16 min read

As we were teaching class this very Wednesday, September 17th, news broke that Google DeepMind’s Gemini achieved gold medal level performance at the 2025 International Collegiate Programming Contest (ICPC) World Finals, solving 10 of 12 complex algorithmic problems in the world’s most prestigious competitive programming competition.Gemini’s ICPC performance builds on...

Read More →

Week 2: The Fundamental Challenges Nobody Talks About

September 08, 2024 • Architecture • 13 min read

Here’s what nobody tells you about applying AI to computer architecture: it’s not just harder than other domains. It’s fundamentally different in ways that make most AI success stories irrelevant. This week, we confronted why the techniques that conquered vision, language, and games stumble when faced with cache hierarchies and...

Read More →

Week 1: The End of an Era, The Dawn of Architecture 2.0

September 03, 2024 • Architecture • 11 min read

Moore’s Law is dying. Dennard scaling ended years ago.Dennard scaling, formulated by Robert Dennard at IBM in 1974, observed that as transistors became smaller, their switching voltage and current could be reduced proportionally, keeping power density roughly constant. This meant each new generation delivered faster processors without exponentially increasing power...

Read More →

Follow the Frontier

New posts drop every Monday. Don’t miss the insights:

These are the conversations that will define the next decade of computer systems. Be part of them.