- A rebuttal by a researcher within Google who wrote this at the same time as the "AlphaChip" work was going on ("Stronger Baselines for Evaluating Deep Reinforcement Learning in Chip Placement"): http://47.190.89.225/pub/education/MLcontra.pdf
- The 2023 ISPD paper from a group at UCSD ("Assessment of Reinforcement Learning for Macro Placement"): https://vlsicad.ucsd.edu/Publications/Conferences/396/c396.p...
- A paper from Igor Markov which critically evaluates the "AlphaChip" algorithm ("The False Dawn: Reevaluating Google's Reinforcement Learning for Chip Macro Placement"): https://arxiv.org/pdf/2306.09633
In short, the Google authors did not fairly evaluate their RL macro placement algorithm against other SOTA algorithms: rather they claim to perform better than a human at macro placement, which is far short of what mixed-placement algorithms are capable of today. The RL technique also requires significantly more compute than other algorithms and ultimately is learning a surrogate function for placement iteration rather than learning any novel representation of the placement problem itself.
In full disclosure, I am quite skeptical of their work and wrote a detailed post on my website: https://vighneshiyer.com/misc/ml-for-placement/
The AlphaChip authors address criticism in their addendum, and in a prior statement from the co-lead authors: https://www.nature.com/articles/s41586-024-08032-5 , https://www.annagoldie.com/home/statement
- The 2023 ISPD paper didn't pre-train at all. This means no learning from experience, for a learning-based algorithm. I feel like you can stop reading there.
- The ISPD paper and the MLcontra paper both used much larger older technology node sizes, which have pretty different physical properties. TPU has a sub 10nm technology node size, whereas ISPD uses 45nm and 12nm. These are really different from a physical design perspective. Even worse, MLcontra uses a truly ancient benchmark with >100nm technology node size.
Markov's paper just summarizes the other two.
(Incidentally, none of ISPD / MLcontra / Markov were peer reviewed - ISPD 2023 was an invited paper.)
There's a lot of other stuff wrong with the ISPD paper and the MLcontra paper - happy to go into it - and a ton of weird financial incentives lurking in the background. Commercial EDA companies do NOT want a free open-source tool like AlphaChip to take over.
Reading your post, I appreciate the thoroughness, but it seems like you are too quick to let ISPD 2023 off the hook for failing to pre-train and using less compute. The code for pre-training is just the code for training --- you train on some chips, and you save and reuse the weights between runs. There's really no excuse for failing to do this, and the original Nature paper described at length how valuable pre-training was. Given how different TPU is from the chips they were evaluating on, they should have done their own pre-training, regardless of whether the AlphaChip team released a pre-trained checkpoint on TPU.
(Using less compute isn't just about making it take longer - ISPD 2023 used half as many GPUs and 1/20th as many RL experience collectors, which may screw with the dynamics of the RL job. And... why not just match the original authors' compute, anyway? Isn't this supposed to be a reproduction attempt? I really do not understand their decisions here.)
Kahng's ISPD 2023 paper is not in dispute - no established experts objected to it. The Nature paper is in dispute. Dozens of experts objected to it: Kahng, Cheng, Markov, Madden, Lienig, Swartz objected publically.
The fact that Kahng's paper was invited doesn't mean it wasn't peer reviewed. I checked with ISPD chairs in 2023 - Kahng's paper was thoroughly reviewed and went through multiple rounds of comments. Do you accept it now? Would you accept peer-reviewed versions of other papers?
Kahng is the most prominent active researcher in this field. If anyone knows this stuff, it's Kahng. There were also five other authors in that paper, including another celebrated professor, Cheng.
The pre-training thing was disclaimed in the Google release. No code, data or instructions for pretraining were given by Google for years. The instructions said clearly: you can get results comparable to Nature without pre-training.
The "much older technology" is also a bogus issue because the HPWL scales linearly and is reported by all commercial tools. Rectangles are rectangles. This is textbook material. But Kahng etc al prepared some very fresh examples, including NVDLA, with two recent technologies. Guess what, RL did poorly on those. Are you accepting this result?
The bit about financial incentives and open-source is blatantly bogus, as Kahng leads OpenROAD - the main open-source EDA framework. He is not employed by any EDA companies. It is Google who has huge incentives here, see Demis Hassabis tweet "our chips are so good...".
The "Stronger Baselines" matched compute resources exactly. Kahng and his coauthors performed fair comparisons between annealing and RL, giving the same resources to each. Giving greater resources is unlikely to change results. This was thoroughly addressed in Kahng's FAQ - if you only could read that.
The resources used by Google were huge. Cadence tools in Kahng's paper ran hundreds times faster and produced better results. That is as conclusive as it gets.
It doesn't take a Ph.D. to understand fair comparisons.
Other commenters already addressed the pre-training issue. Please kindly include a link to Kahng's 2023 discussion addressing your complaints. Otherwise, you are unfairly supporting those people you know.
Kahng's placer is open-source and was used in the Nature paper. It does not make sense to accuse Kahng of colluding with companies against open-source.
https://en.wikipedia.org/wiki/Top_Chess_Engine_Championship
So perhaps the critics had a point there.
This is what you get if you make academic researchers compete for citation counts.
Pretraining seems to be an important aspect here, and it makes sense that such pretraining requires good examples, which unfortunately for the free lunch people, is not available to the public.
That's what you get when you let big companies do fundamental research. Would it be better if the companies did not publish anything about their research at all?
It all feels a bit unproductive to attack one another.
Whichever approach ends up winning is improved by careful evaluation and replication of results
When you see a chip that has the datapath identified and laid out properly by a computer algorithm, you've got something. If not, it's vapor.
So, if your layout still looks like a random rat's nest? Nope.
If even a random person can see that your layout actually follows the obvious symmetric patterns from bit 0 to bit 63, maybe you've got something worth looking at.
Analog/RF is a little tougher to evaluate because the smaller number of building blocks means you can use Moore's Law to brute force things much more exhaustively, but if things "looks pretty" then you've got something. If it looks weird, you don't.
They must feel vindicated by their work turning out to be so fruitful now.
[1] https://www.theregister.com/AMP/2023/03/27/google_ai_chip_pa...
[2] https://regmedia.co.uk/2023/03/26/satrajit_vs_google.pdf
I think it is time for you to take a deep breath and think about what you are doing and why.
You seem to be obsessed with the idea that this work is overrated. MediaTek and Google don't think so, and use it in production for their chips, including TPU, Dimensity, Axion, and others. If you're right and they're wrong, using this method loses them money. If it's the other way around, then using this method makes them gain money.
Please read PG's post and ask yourself if it applies to you: https://www.paulgraham.com/fh.html
Chatterjee settled his case. He has moved on. This is not some product being sold -- it is a free, open-source tool. People who see value in it use it; others don't, and so they don't. This is how it always works, and it's fine.
They don’t produce but they are tailored for them just the same. “We have” doesn’t have to mean “we made”. They don’t say it as such here but elsewhere they refer to the IP they can make available, which can also be made in house or cross licensed and still count as “we have”.
Without knowing much, my guess is that “quality” of a chip design is multifaceted and heavily dependent on the use case. That is the ideal chip for a data center would look very different from those for a mobile phone camera or automobile.
So again what does “better” mean in the context of this particular problem / task.
Floorplanning/placement/synthesis is a billion dollar industry, so if their approach were really revolutionary they would be selling the technology, not wasting their time writing blog posts about it.
https://research.google/pubs/spanner-googles-globally-distri...
or Bigtable?
https://research.google/pubs/bigtable-a-distributed-storage-...
or GFS?
or MapReduce?
or Borg?
or...I think you get the idea.
Maybe all together, but I don't think automatic placement algorithms are a billion dollar industry. There's so much more to it than that.
(no paywall): https://www.cl.cam.ac.uk/~ey204/teaching/ACS/R244_2021_2022/...
[1] https://en.wikipedia.org/wiki/Eurisko
What's more, Eurisco was then used in designing Traveler TCS' game fleet of battle spaceships. And Eurisco used symmetry-based placement learned from VLSI design in the design of the spaceships' fleet.
Can AlphaChip's heuistics be used anywhere else?
Instead they could have demonstrated their amazing method on any number of standard NP hard optimization problems e.g. traveling salesman, bin packing, ILP, etc. where we can generate tons of examples and verify easily whether it produces better results than other solvers or not.
This is why many in the chip design and optimization community felt that the paper was suspicious. Even with this addendum they adamantly refuse to share any results that can be independently verified.
It is not obscure (in chip design). If anything it is one of the most easily reachable problems. Almost every other PhD student in the field has implemented a macro placer, even if just for fun, and there are frequent academic competitions. A lot of design houses also roll their own macro placers since it's not a difficult problem and generally adding a bit of knowledge of your design style can help you gain an extra % over the generic commercial tools.
It does not surprise me at all that they decided to start with this for their foray into chip EDA. It's the minimum effort route.
Chips designed with the help of AlphaChip are in datacenters and Samsung phones, right now. That's pretty neat!
I assume that the human benchmark is a human using existing EDA tools, not a guy with a pocket protector and a roll of tape.
To quote certain popular TV series .... Sorry, are you from the past? Do your "production" chips only have a couple dozen macros or what?
What nonsense! XD
Also: when is this coming to KiCad? :)
PS: It would also be nice to apply a similar algorithm to graph drawing (e.g. trying to optimize for human readability instead of electrical performance).
We're in the timeline that took the wrong path. The other world has isolinear memory, which can be used for compute, or as memory, down to the LUT level. Everything runs at a consistent speed, and hardware faults LUTs can be routed around easily.
Better architectures without the yearly investment train will no longer be better quite quickly.
You would need to be 100x to 1000x better in order to pull the investment train onto your tracks.
Don’t has been impossible for decades.
Even so, I think we will see such a change in my lifetime.
AI could be that use case that has a strong enough demand pull to make it happen.
We will see.
But if you do pay attention to the programming model, they're unusable. You'll see that dozens of these approaches have come and gone, because it's impossible to write software for them.
I don't think it's necessarily demand or any particular calculation that makes things happen. I think people including investors are just herd animals. They aren't enthusiastic until they see the herd moving and then they want in.
I don’t want art that wasn’t made by a human, no matter how visually stunning or indistinguishable it is.
Imagine your favorite movie, the most moving book. You read it, it changed you, then you found out it was an AI that generated it in a mere 10 seconds.
Artificial sentimentality is useless in the face of reality. That human endeavor is simply data points along an multi-dimensional best fit curve.
TPU v5e [1]: not available for purchase, only through GCP, storage=5B, LLM-Model=7B, efficiency=393TFLOP.
Forget LLM's. What DeepMind is doing seems more like how an AI will rule, in the world. Building real world models, and applying game logic like winning.
LLM's will just be the text/voice interface to what DeepMind is building.
Protein Folding? That was against a defined data set and other organizations.
Nobody can re-produce? Isn't that the definition of a competitive advantage?
They are building something others can't, and that is bad? That is what companies do.
For example, how much better are these latest gen TPU's when compared to NVidia's equivalent offering ?
Re:using RL and other types AI assistance for chip design, Nvidia and others are doing this too
I'd even dare to claim we are already at the point where the growth has stopped, but even then you will only see the effect in a decade or so as there are still many small low-hanging fruits you can fix, but no big improvements.
Practically speaking, though, maintaining Moore's law would have been economically prohibitive if circuit design and layout had not been automated.
> Synopsys DSO.ai autonomously explores multiple design spaces to optimize PPA metrics while minimizing tradeoffs for the target application. It uses AI to navigate the design-technology solution space by automatically adjusting or fine-tuning the inputs to the design (e.g., settings, constraints, process, flow, hierarchy, and library) to find the best PPA targets.
I think the next step is arrays of memory-based compute.
GPUs still treat memory as separate from compute, they just have wider bottlenecks than CPUs.
