Thanks for posting this, that's how I first found out about Dan's experiment!
SSD speed doubled in the M5P/M generation, that makes it usable!
I think one paper under the radar is "KV Prediction for Improved Time to First Token" https://arxiv.org/abs/2410.08391 which hopefully can help with prefill for Flash streaming.
That’s exactly what I thought about. Getting my hands on an M5 Max this week and going to see hows Dan’s experiment performs with faster I/O. Also going to experiment with running active parameters at Q6 or Q8 since output is I/O bottlenecked there should room for higher accuracy compute.
That was a very good summary. One detail the post could use is mentioning that 4 or 10 experts invoked where selected from the 512 experts the model has per layer (to give an idea of the savings).
A similar approach was recently featured here: https://news.ycombinator.com/item?id=47476422 Though iPhone Pro has very limited RAM (12GB total) which you still need for the active part of the model. (Unless you want to use Intel Optane wearout-resistant storage, but that was power hungry and thus unsuitable to a mobile device.)
Yes but most people are still running MoE models with all experts loaded in RAM! This experiment shows quite clearly that some experts are only rarely needed, so you do benefit from not caching every single expert-layer in RAM at all times.
That's not what this test shows. It's just loading the parts of the model that are used in an on-demand fashion from flash.
The iPhone 17 Pro only has 12GB of RAM. This is a -17B MoE model. Even quantized, you can only realistically fit one expert in RAM at a time. Maybe 2 with extreme quantization. It's just swapping them out constantly.
If some of the experts were unused then you could distill them away. This has been tried! You can find reduced MoE models that strip away some of the experts, though it's ony a small number. Their output is not good. You really need all of the experts to get the model's quality.
The writeup from the earlier experiment (running on a MacBook Pro) shows quite clearly that expert routing choices are far from uniform, and that some layer-experts are only used rarely. So you can save some RAM footprint even while swapping quite rarely.
I understand, but this isn't just a matter of not caching some experts. This is a 397B model on a device with 12GB of RAM. It's basically swapping experts out all the time, even if the distribution isn't uniform.
When the individual expert sizes are similar to the entire size of the RAM on the device, that's your only option.
"Individual experts" is a bit of a red-herring, what matters is expert-layers (this is the granularity of routing decisions), and these are small as mentioned by the original writeup. The filesystem cache does a tolerable job of keeping the "often used" ones around while evicting those that aren't needed (this is what their "Trust the OS" point is about). Of course they're also reducing the amount of active experts and quantizing a lot, AIUI this iPhone experiment uses Q1 and the MacBook was Q2.
If I only use an LLM to ask questions about programming in one specific programming language, can I distill away other experts and get all the answers I need from a single expert? Or is it still different experts that end up handling the question depending on what else is in the question? For example, if I say “plan a static web server in Rust” it might use expert A for that, but if I say “implement a guessing game in Rust” it might use expert B, and so on?
A model "where expert switches are less necessary" is hard to tell apart from a model that just has fewer total experts. I'm not sure whether that will be a good approach. "How often to switch" also depends on how much excess RAM has been available in the system to keep layers opportunistically cached from the previous token(s). There's no one-size fits all decision.
I’m so confused in these comments right now — I thought you had to load an entire MoE model and sparseness just made it so you can traverse the model more quickly.
I had a dream that everyone had super intelligent AIs in their pockets, and yet all they did was doomscroll and catfish...shortly before everything was destroyed.
I wonder if anyone has made a liquid cooling system for ipads / phones.
Like, a sealed thing that seals onto the back of the device and circulates cooling water directly against the back surface.
I have a small portable fan that I place under it basically any time I use it for any development work. It gets thermally throttled pretty fast otherwise. It's definitely the wrong machine for my needs but it's what I gotta work with for now.
Running larger-than-RAM LLMs is an interesting trick, but it's not practical. The output would be extremely slow and your computer would be burning a lot of power to get there. The heavy quantizations and other tricks (like reducing the number of active experts) used in these demos severely degrade the quality.
With 64GB of RAM you should look into Qwen3.5-27B or Qwen3.5-35B-A3B. I suggest Q5 quantization at most from my experience. Q4 works on short responses but gets weird in longer conversations.
>I suggest Q5 quantization at most from my experience. Q4 works on short responses but gets weird in longer conversations.
There are dynamic quants such as Unsloth which quantize only certain layers to Q4. Some layers are more sensitive to quantization than others. Smaller models are more sensitive to quantization than the larger ones. There are also different quantization algorithms, with different levels of degradation. So I think it's somewhat wrong to put "Q4" under one umbrella. It all depends.
I've tried a number of experiments, and agree completely. If it doesn't fit in RAM, it's so slow as to be impractical and almost useless. If you're running things overnight, then maybe, but expect to wait a very long time for any answers.
Current local-AI frameworks do a bad job of supporting the doesn't-fit-in-RAM case, though. Especially when running combined CPU+GPU inference. If you aren't very careful about how you run these experiments, the framework loads all weights from disk into RAM only for the OS to swap them all out (instead of mmap-ing the weights in from an existing file, or doing something morally equivalent as with the original MacBook Pro experiment) which is quite wasteful!
This approach also makes less sense for discrete GPUs where VRAM is quite fast but scarce, and the GPU's PCIe link is a key bottleneck. I suppose it starts to make sense again once you're running the expert layers with CPU+RAM.
Yes, SSD speed is critical though. The repo has macOS builds for CLI and Desktop.
It's early stages though. M4 Max gets 10-15 TPS on 400B depending on quantization. Compute is an issue too; a lot of code is PoC level.
I have a 64G/1T Studio with an M1 Ultra. You can probably run this model to say you’ve done it but it wouldn’t be very practical.
Also I wouldn’t trust 3-bit quantization for anything real. I run a 5-bit qwen3.5-35b-A3B MoE model on my studio for coding tasks and even the 4-bit quant was more flaky (hallucinations, and sometimes it would think about running tools calls and just not run them, lol).
If you decided to give it a go make sure to use the MLX over the GGUF version! You’ll get a bit more speed out of it.
I installed Termux on an old Android phone last week (running LineageOS), and then using Termux installed Ollama and a small model. It ran terribly, but it did run.
Somehow this reminds me of the time I downloaded, compiled, and ran a Bitcoin miner with the app called Linux Deploy on my then-new Galaxy Note (the thing called phablet that is now positively small). It ran terribly, but it did run!
Having a complete computer in my pocket was very new to me, coming from Nokia where I struggled (as a teenager) to get any software running besides some JS in a browser. I still don't know where they hid whatever you needed to make apps for this device. Android's power, for me, was being able to hack on it (in the HN sense of the word)
Qwen's MoE models are god awful when they are only running 2B parameters or whatever they downscale to while active. It isn't a 400B model if there's only several orders of magnitude less parameters active when you're actually inferencing...
Sometimes it looks like the purpose of those hundreds of billions of parameters and those apparent feats of engineering, is to get others to tell you how clever you are. Now we have even automated that.
This is awesome! How far away are we from a model of this capability level running at 100 t/s? It's unclear to me if we'll see it from miniaturization first or from hardware gains
One big bottleneck is SRAM cost. Even an 8b model would probably end up being hundreds of dollars to run locally on that kind of hardware. Especially unpalatable if the model quality keeps advancing year-by-year.
> Or we develop a new silicon process that can mimic synaptic weights in biology. Synapses have plasticity.
It's amazing to me that people consider this to be more realistic than FAANG collaborating on a CUDA-killer. I guess Nvidia really does deserve their valuation.
I mean if it was small enough to fit in an iPhone why not? Every year you would fabricate the new chip with the best model. They do it already with the camera pipeline chips.
On smartphones? It’s not worth it to run a model this size on a device like this. A smaller fine-tuned model for specific use cases is not only faster, but possibly more accurate when tuned to specific use cases. All those gigs of unnecessary knowledge are useless to perform tasks usually done on smartphones.
It will never be possible on a smart phone. I know that sounds cynical, but there's basically no path to making this possible from an engineering perspective.
A long time. But check out Apollo from Liquid AI, the LFM2 models run pretty fast on a phone and are surprisingly capable. Not as a knowledge database but to help process search results, solve math problems, stuff like that.
Probably 15 to 20 years, if ever. This phone is only running this model in the technical sense of running, but not in a practical sense. Ignore the 0.4tk/s, that's nothing. What's really makes this example bullshit is the fact that there is no way the phone has a enough ram to hold any reasonable amount of context for that model. Context requirements are not insignificant, and as the context grows, the speed of the output will be even slower.
Realistically you need +300GB/s fast access memory to the accelerator, with enough memory to fully hold at least greater than 4bit quants. That's at least 380GB of memory. You can gimmick a demo like this with an ssd, but the ssd is just not fast enough to meet the minim specs for anything more than showing off a neat trick on twitter.
The only hope for a handheld execution of a practical, and capable AI model is both an algorithmic breakthrough that does way more with less, and custom silicon designed for running that type of model. The transformer architecture is neat, but it's just not up for that task, and I doubt anyone's really going to want to build silicon for it.
KV-cache is still quite small compared to the weights. It can stay in memory for reasonable context length, or be streamed to storage as a last resort. This actually doesn't impact performance too much, since we were already limited by having to stream in the much larger weights.
> Realistically you need +300GB/s fast access memory to the accelerator, with enough memory to fully hold at least greater than 4bit quants.
The latest M5 MacBook Pro's start at 307 GB/s memory bandwidth, the 32-core GPU M5 Max gets 460 GB/s, and the 40-core M5 Max gets 614 GB/s. The CPU, GPU, and Neural Engine all share the memory.
The A19/A19 Pro in the current iPhone 17 line is essentially the same processor (minus the laptop and desktop features that aren’t needed for a phone), so it would seem we're not that far off from being able to run sophisticated AI models on a phone.
Looked at a certain way it's incredible that a 40-odd year old comedy sci-fi series is so accurate about the expected quality of (at least some) AI output.
Which makes it even funnier.
It makes me a little sad that Douglas Adams didn't live to see it.
You also have the problem that if the both the ultimate answer to life the universe and everything, and the ultimate question to life the universe and everything, are know at the same time in the same universe. The universe is spontaneously replaced with a slightly more absurd universe to ensure that both the question and answer become meaningless.
To quote the message from the universes creators to its creation “We apologise for the inconvenience”. Does seem to sum up Douglas Adam’s views on absurdity of life.
2 years ago, LLMs failed at answering coherently. Last year, they failed at answering fast on optimized servers. Now, they're failing at answering fast on underpowered handheld devices... I can't wait to see what they'll be failing to do next year.
There are many metrics for “better” and “worse”. It is entirely possible for an AI system to be better in the sense of hallucination while also being of less utility. An arrogant prick who’s always correct isn’t always a good person to have on your team, right?
You need fast storage to make it worthwhile. PCIe x4 5.0 is a reasonable minimum. Or multiple PCIe x4 4.0 accessed in parallel, but this is challenging since the individual expert-layers are usually small. Intel Optane drives are worth experimenting with for the latter (they are stuck on PCIe 4.0) purely for their good random-read properties (quite aside from their wearout resistance, which opens up use for KV-cache and even activations).
Apple’s unified memory architecture plays a huge part in this. This will trigger a large scale rearchitecture of mobile hardware across the board. I am sure they are already underway.
I understand this is for a demo but do we really need a 400B model in the mobile? A 10B model would do fine right? What do we miss with a pared down one?
> Apple’s unified memory architecture plays a huge part in this. This will trigger a large scale rearchitecture of mobile hardware across the board. I am sure they are already underway.
Putting the GPU and CPU together and having them both access the same physical memory is standard for phone design.
Mobile phones don't have separate GPUs and separate VRAM like some desktops.
This isn't a new thing and it's not unique to Apple
> I understand this is for a demo but do we really need a 400B model in the mobile? A 10B model would do fine right? What do we miss with a pared down one?
There is already a smaller model in this series that fits nicely into the iPhone (with some quantization): Qwen3.5 9B.
The smaller the model, the less accurate and capable it is. That's the tradeoff.
> Putting the GPU and CPU together and having them both access the same physical memory is standard for phone design.
> Mobile phones don't have separate GPUs and separate VRAM like some desktops.
That's true. The difference is the iPhone has wider memory buses and uses faster LPDDR5 memory. Apple places the RAM dies directly on the same package as the SoC (PoP — Package on Package), minimizing latency. Some Android phones have started to do this, too.
iOS is tuned to this architecture which wouldn't be the case across many different Android hardware configurations.
> The difference is the iPhone has wider memory buses and uses faster LPDDR5 memory. Apple places the RAM dies directly on the same package as the SoC (PoP — Package on Package), minimizing latency. Some Android phones have started to do this, too.
Package-on-Package has been used in mobile SoCs for a long time. This wasn't an Apple invention. It's not new, either. It's been this way for 10+ years. Even cheap Raspberry Pi models have used package-on-package memory.
The memory bandwidth of flagship iPhone models is similar to the memory bandwidth of flagship Android phones.
There's nothing uniquely Apple in this. This is just how mobile SoCs have been designed for a long time.
> The memory bandwidth of flagship iPhone models is similar to the memory bandwidth of flagship Android phones
More correct to say that the memory bandwidth of ALL iPhone models is similar to the memory bandwidth of flagship Android models. The A18 and A18 pro do not differ in memory bandwidth.
Is it though? I would say 'proof of concept' instead.
The fact that it's running on a phone now just sets the goalpost and gets everyone excited about it: add more RAM and GPU to the next iPhone and it's not a toy anymore. Co-incidentally, phone companies also have thousands of engineers sitting around wondering what to do in their next release to convince consumers to buy ...
'Toy' and 'proof of concept' are synonymous. What this really opens up is running non-toy models like Qwen3.5 35B-A3B, which are still considered very large in the mobile device context. Yes, it's too slow for interactivity, but if you acknowledge that it's supposed to deliver "Pro" level inference it works quite fine.
> add more RAM and GPU to the next iPhone and it's not a toy anymore
We're not going to get more RAM and GPU in consumer devices.
All of the supply is going into data center build outs. As the hyper scaler gamble on the future continues, we get left with weaker (or more expensive) devices - not stronger ones.
The market makers make more money if we're left to thin clients. They're also the ones who control supply and the shapes of devices.
It's been known to people working in the space for a long time. Heck, I was working on similar stuff for the Maxwell and later Pascal over a decade ago.
You do have a lot of "MLEs" and "Data Scientists" who only know basic PyTorch and SKLearn, but that kind of fat is being trimmed industry wide now.
Domain experience remains gold, especially in a market like today's.
I have some macro opinions about Apple - not sure if I'm correct, but tell me what you think.
Apple has always seen RAM as an economic advantage for their platform: Make the development effort to ensure that the OS and apps work well with minimal memory and save billions every year in hardware costs. In 2026, iPhones still come with 8Gb of RAM, Pro/Max come with 12Gb.
The problem is that AI (ML/LLM training and inference) are areas where you can't get around the need for copious amounts of fast working memory. (Thus the critical shortage of RAM at the moment as AI data centers consume as many memory chips as possible.)
Unless there's something I don't know (which is more than possible) Apple can't code their way around this problem, nor create specialized SoCs with ML cores that obviate the need for lots and lots of RAM.
So, it's going to be interesting whether they accept this reality and we start seeing the iPhones in the future with 16Gb, 32Gb or more as standard in order to make AI performant. And if they give up on adding AI to the billions of iPhones with minimal RAM already out there.
As a side note, 8Gb of RAM hasn't been enough for a decade. It prevents basic tasks like keeping web tabs live in the background. My pet peeve is having just a few websites open, and having the page refresh when swapping between them because of aggressive memory management.
To me, Apple's obvious strength is pushing AI to the edge as much as possible. While other companies are investing in massive data centers which will have millions of chips that will be outdated within the next couple years, Apple will be able to incrementally improve their ML/AI features by running on the latest and greatest chips every year. Apple has a huge advantage in that they can design their chips with a mega high speed bus, which is just as important as the quantity of RAM.
But all that depends on Apple's willingness to accept that RAM isn't an area they can skimp on any more, and I'm not sure they will.
Sorry for the brain dump. I'd love to be educated on this in case I'm totally off base.
If you're loading gigabytes of model weights into memory, you're also pushing gigabytes through the compute for inference. No matter how you slice it, no matter how dense you make the chips, that's going to cost a lot of energy. It's too energy intensive, simple as.
"On device" inference (for large LLM I mean) is a total red herring. You basically never want to do it unless you have unique privacy considerations and you've got a power cable attached to the wall. For a phone maybe you would want a very small model (like 3B something in that size) for Siri-like capabilities.
On a phone, each query/response is going to cost you 0.5% of your battery. That just isn't tenable for the way these models are being used.
Try this for yourself. Load a 7B model on your laptop and talk to it for 30 minutes. These things suck energy like a vacuum, even the shitty models. A network round trip costs gets you hundreds of tokens from a SOTA model and costs 1 joule. By contrast, a single forward pass (one token) of a shitty 7b model costs 1 joule. It's just not tenable.
Huh, I hadn't thought of battery limitations. Good call. My initial reaction is that bigger/better batteries, hyper fast recharge times and more efficient processors might address this issue, but I need to learn more about it.
That said, power consumption is one of the reasons I think pushing this stuff to the edge is the only real path for AI in terms of a business model. It basically spreads the load and passes the cost of power to the end user, rather than trying to figure out how to pay for it at the data center level.
In a recent episode of Dwarkesh the guest who is a semiconductor industry analyst predicted that an iPhone will increase in price by about $250 for the same stuff due to increased ram/chip costs from AI. Apple will not be able to afford to put a bunch more RAM into the phones and still sell them.
> In a recent episode of Dwarkesh the guest who is a semiconductor industry analyst predicted that an iPhone will increase in price by about $250 for the same stuff due to increased ram/chip costs from AI. Apple will not be able to afford to put a bunch more RAM into the phones and still sell them.
Apple recently stated on an earnings call they signed contracts with RAM vendors before prices got out of control, so they should be good for a while. Nvidia also uses TSMC for their chips, which may affect A series and M series chip production.
Yes, TSMC has a plant in Arizona but my understanding is they can't make the cutting edge chips there; at least not yet.
I think this is roughly true, but instead RAM will remain a discriminator even moreso. If the scaling laws apple has domain over are compute and model size, then they'll pretty easily be able to map that into their existing price tiers.
Pros will want higher intelligence or throughput. Less demanding or knowledgeable customers will get price-funneled to what Apple thinks is the market premium for their use case.
It'll probably be a little harder to keep their developers RAM disciplined (if that's even still true) for typical concerns. But model swap will be a big deal. The same exit vs voice issues will exist for apple customers but the margin logic seems to remain.
Possibly this just isn't the generation of hardware to solve this problem in? We're like, what three or four years in at most, and only barely two in towards AI assisted development being practical. I wouldn't want to be the first mover here, and I don't know if it's a good point in history to try and solve the problem. Everything we're doing right now with AI, we will likely not be doing in five years. If I were running a company like Apple, I'd just sit on the problem until the technology stabilizes and matures.
If I was running a company like Apple, I'd be working with Khronos to kill CUDA since yesterday. There are multiple trillions of dollars that could be Apple's if they sign CUDA drivers on macOS, or create a CUDA-compatible layer. Instead, Apple is spinning their wheels and promoting nothingburger technology like the NPU and MPS.
It's not like Apple's GPU designs are world-class anyways, they're basically neck-and-neck with AMD for raster efficiency. Except unlike AMD, Apple has all the resources in the world to compete with Nvidia and simply chooses to sit on their ass.
CUDA is not the real issue, AMD's HIP offers source-level compatibility with CUDA code, and ZLUDA even provides raw binary compatibility. nVidia GPUs really are quite good, and the projected advantages of going multi-vendor just aren't worth the hassle given the amount of architecture-specificity GPUs are going to have.
Okay, then don't kill CUDA, just sign CUDA drivers on macOS instead and quit pretending like MPS is a world-class solution. There are trillions on the table, this is not an unsolvable issue.
Admittedly, my use of CUDA and Metal is fairly surface-level. But I have had great success using LLMs to convert whole gaussian splatting CUDA codebases to Metal. It's not ideal for maintainability and not 1:1, but if CUDA was a moat for NVIDIA, I believe LLMs have dealt a blow to it.
You can convert CUDA codebases to Vulkan and DirectX code, for all the good it does you. You're still constrained by the architecture of the GPU, and Apple Silicon GPUs pre-M5 are all raster-optimized. The hardware is the moat.
Apple technically hasn't supported the professional GPGPU workflow for over a decade. macOS doesn't support CUDA anymore, Apple abandoned OpenCL on all of their platforms and Metal is a bare-minimum effort equivalent to what Windows, Android and Linux get for free. Dedicated matmul hardware is what Apple should have added to the M1 instead of wasting silicon on sluggish, rinky-dink NPUs. The M5 is a day late and a dollar short.
Don't get me wrong, it's an awesome achievement, but 0.6s token/s at presumably fairly heavy compute (and battery), on a mobile device? There aren't too many use cases for that :)
I can't understand why this is a surprise to anyone. An iphone is still a computer, of course it can run any model that fits in storage albiet very slowly. The implementation is impressive I guess but I don't see how this is a novel capability. And for 0.6t/s, its not a cost efficient hardware for doing it. The iphone can also render pixar movies if you let it run long enough, mine bitcoin with a pathetic hashrate, and do weather simulations but not in time for the forecast to be relevant.
We haven't had phones running laptop-grade CPUs/GPUs for that long, and that is a very real hardware feat. Likewise, nobody would've said running a 400b LLM on a low-end laptop was feasible, and that is very much a software triumph.
We've had solid CPUs for a while, but GPUs have lagged behind (and they're the ones that matter for this particular application). iPhones still lead by a comfortable margin on this front, but have historically been pretty limited on the IO front (only supported USB2 speeds until recently).
The GPUs are perfectly solid. Cheap Android handsets have shipped with Vulkan compliance for almost a decade now; the GPUs are equally-featured to consoles and PCs. The same goes for Apple handsets that run byte-identical Metal Compute Shaders to the Mac. For desktop use they are perfectly amenable. The hardware lacks nothing required for inference or gaming that dGPUs ordinarily support.
And even if you raise the requirements, we still have to contend with cheap CUDA-capable GPUs like the one in the ($300!!!) Nintendo Switch, or the Jetson SOCs. The mobile market has had tons of high-speed/low-power options for a very long time now.
The iPhone 17 Pro launched 8 months ago with 50% more RAM and about double the inference performance of the previous iPhone Pro (also 10x prompt processing speed).
It wasn't considered impossible. There are examples of large MoE LLMs running on small hardware all over the internet, like giant models on Raspberry Pi 5.
It's just so slow that nobody pursued it seriously. It's fun to see these tricks implemented, but even on this 2025 top spec iPhone Pro the output is 100X slower than output from hosted services.
If the bottleneck is storage bandwidth that's not "slow". It's only slow if you insist on interactive speeds, but the point of this is that you can run cheap inference in bulk on very low-end hardware.
You're simply pointing out that most people who use AI today expect interactive speeds. You're right that the point here is not raw power efficiency (having to read from storage will impact energy per operation, and datacenter-scale AI hardware beats edge hardware anyway by that metric) but the ability to repurpose cheaper, lesser-scale hardware is also compelling.
The real improvement will be when the software engineers get into the training loop. Then we can have MoE that use cache-friendly expert utilisation and maybe even learned prefetching for what the next experts will be.
> maybe even learned prefetching for what the next experts will be
Experts are predicted by layer and the individual layer reads are quite small, so this is not really feasible. There's just not enough information to guide a prefetch.
I mean, by any reasonable standard it still is. Almost any computer can run an llm, it's just a matter of how fast, and 0.4k/s (peak before first token) is not really considered running. It's a demo, but practically speaking entirely useless.
Devils advocate - this actually shows how promising TinyML and EdgeML capabilities are. SoCs comparable to the A19 Pro are highly likely to be commodified in the next 3-5 years in the same manner that SoCs comparable to the A13 already are.
Apple is already one of the winners of the AI race. It’s making much more profit (ie it ain’t losing money) on AI off of ChatGPT, Claude, Grok (you would be surprised at how many incels pay to make AI generated porn videos) subscriptions through the App Store.
It’s only paying Google $1 billion a year for access to Gemini for Siri
Which is mostly insane amounts of debt leveraged entirely on the moonshot that they will find a way to turn a profit on it within the next couple years.
Apple’s bet is intelligent, the “presumed winners” are hedging our economic stability on a miracle, like a shaking gambling addict at a horse race who just withdrew his rent money.
Most of the influencer content I saw demonstrating LLMs on multiple 512gb Mac Studios over Thunderbolt networking used Macs borrowed from Apple PR that were returned afterwards - network chuck, Jeff Geerling et al didn't actually buy the 4 or 5 512gb Mac Studios used in their corresponding local LLM videos.
The financial math on actually buying over $40k worth of Mac for 1 to 2 youtube videos probably doesn't work that well, even for the really big players.
They don't offer the 512 gig RAM variant anymore. Outside of social media influencers and the occasional AI researcher, the market for $10K desktops is vanishingly small.
Huh, interesting. I wonder if there's a premium price right now for the one on my desk...
Pretty sure the M5 Ultra will be out after WWDC, so my M3 Ultra is (while still completely capable of fulfilling my needs) looking a bit long in the tooth. If I can get a good price for it now, I might be able to offset most of the M5 post WWDC...
It's crazy to see a 400B model running on an iPhone. But moving forward, as the information density and architectural efficiency of smaller models continue to increase, getting high-quality, real-time inference on mobile is going to become trivial.
They will. Either new architectures will come out that give us greater efficiency, or we will hit a point where the main thing we can do is shove more training time onto these weights to get more per byte. Similar thing is already happening organically when it comes to efficient token use; see for instance https://github.com/qlabs-eng/slowrun.
The "if" is fair. But when scaling hits diminishing returns, the field is forced to look at architectures with better capacity-per-parameter tradeoffs. It's happened before, maybe it'll happen again now.
The heat problem is going to be the real constraint here. I've been running smaller models locally for some internal tooling at work and even those make my MacBook sound like a jet engine after twenty minutes. A 400B model on a phone seems like a great way to turn your pocket into a hand warmer, even with MoE routing. The unified memory is clever but physics still applies.
Your time-average power budget for things that run on phones is about 0.5W (batteries are about 10Wh and should last at least a day). That's about three orders of magnitude lower than a the GPUs running in datacenters.
Even if battery technology improves you can't have a phone running hot, so there are strong physical limits on the total power budget.
More or less the same applies to laptops, although there you get maybe an additional order of magnitude.
Total gimmick. I guess we're "making progress", but this is will never lead to any useful application other than "Yes, you're absulotely right" bots. What's needed for real applications is 10000× the input token context and 10× the output token speed, so we're off by a factor of ... 100,000×?
> SSD streaming to GPU
Is this solution based on what Apple describes in their 2023 paper 'LLM in a flash' [1]?
1: https://arxiv.org/abs/2312.11514
Yes. I collected some details here: https://simonwillison.net/2026/Mar/18/llm-in-a-flash/
Thanks for posting this, that's how I first found out about Dan's experiment! SSD speed doubled in the M5P/M generation, that makes it usable! I think one paper under the radar is "KV Prediction for Improved Time to First Token" https://arxiv.org/abs/2410.08391 which hopefully can help with prefill for Flash streaming.
That’s exactly what I thought about. Getting my hands on an M5 Max this week and going to see hows Dan’s experiment performs with faster I/O. Also going to experiment with running active parameters at Q6 or Q8 since output is I/O bottlenecked there should room for higher accuracy compute.
Check my repo, I had added some support for GUFF/untloth, Q3,Q5/Q8 https://github.com/Anemll/flash-moe/blob/iOS-App/docs/gguf-h...
To be fair, it's "possible" to run such setup with llama.cpp with ssd offload. It's just abysmal TG speeds. But it's possible.
I guess this is all set up to show off the new high-bandwidth-flash stuff that's due out soon?
That was a very good summary. One detail the post could use is mentioning that 4 or 10 experts invoked where selected from the 512 experts the model has per layer (to give an idea of the savings).
A similar approach was recently featured here: https://news.ycombinator.com/item?id=47476422 Though iPhone Pro has very limited RAM (12GB total) which you still need for the active part of the model. (Unless you want to use Intel Optane wearout-resistant storage, but that was power hungry and thus unsuitable to a mobile device.)
> Though iPhone Pro has very limited RAM (12GB total) which you still need for the active part of the model.
This is why mixture of experts (MoE) models are favored for these demos: Only a portion of the weights are active for each token.
Yes but most people are still running MoE models with all experts loaded in RAM! This experiment shows quite clearly that some experts are only rarely needed, so you do benefit from not caching every single expert-layer in RAM at all times.
That's not what this test shows. It's just loading the parts of the model that are used in an on-demand fashion from flash.
The iPhone 17 Pro only has 12GB of RAM. This is a -17B MoE model. Even quantized, you can only realistically fit one expert in RAM at a time. Maybe 2 with extreme quantization. It's just swapping them out constantly.
If some of the experts were unused then you could distill them away. This has been tried! You can find reduced MoE models that strip away some of the experts, though it's ony a small number. Their output is not good. You really need all of the experts to get the model's quality.
The writeup from the earlier experiment (running on a MacBook Pro) shows quite clearly that expert routing choices are far from uniform, and that some layer-experts are only used rarely. So you can save some RAM footprint even while swapping quite rarely.
I understand, but this isn't just a matter of not caching some experts. This is a 397B model on a device with 12GB of RAM. It's basically swapping experts out all the time, even if the distribution isn't uniform.
When the individual expert sizes are similar to the entire size of the RAM on the device, that's your only option.
"Individual experts" is a bit of a red-herring, what matters is expert-layers (this is the granularity of routing decisions), and these are small as mentioned by the original writeup. The filesystem cache does a tolerable job of keeping the "often used" ones around while evicting those that aren't needed (this is what their "Trust the OS" point is about). Of course they're also reducing the amount of active experts and quantizing a lot, AIUI this iPhone experiment uses Q1 and the MacBook was Q2.
If I only use an LLM to ask questions about programming in one specific programming language, can I distill away other experts and get all the answers I need from a single expert? Or is it still different experts that end up handling the question depending on what else is in the question? For example, if I say “plan a static web server in Rust” it might use expert A for that, but if I say “implement a guessing game in Rust” it might use expert B, and so on?
I hope some company trains their models so that expert switches are less often necessary just for these use cases.
A model "where expert switches are less necessary" is hard to tell apart from a model that just has fewer total experts. I'm not sure whether that will be a good approach. "How often to switch" also depends on how much excess RAM has been available in the system to keep layers opportunistically cached from the previous token(s). There's no one-size fits all decision.
I’m so confused in these comments right now — I thought you had to load an entire MoE model and sparseness just made it so you can traverse the model more quickly.
Yeah, this new post is a continuation of that work.
This is not entirely dissimilar to what Cerebus does with their weights streaming.
And IIRC the Unreal Engine Matrix demo for PS5 was streaming textures directly from SSD to the engine as well?
I had a dream that everyone had super intelligent AIs in their pockets, and yet all they did was doomscroll and catfish...shortly before everything was destroyed.
A modern Nostradamus?
It was just a dream, which quickly turned into a nightmare.
My iPad Air with M2 can run local LLMs rather well. But it gets ridiculously hot within seconds and starts throttling.
I wonder if anyone has made a liquid cooling system for ipads / phones. Like, a sealed thing that seals onto the back of the device and circulates cooling water directly against the back surface.
You're in luck. Lots of phone manufacturers also implement liquid cooling inside the phone too.
https://www.notebookcheck.net/Xiaomi-launches-new-mobile-wat...
A more whimsical method is to put the thing in a glass of water with the cord sticking out. :-)
https://www.reddit.com/r/EmulationOnAndroid/comments/1m269k0...
What about submerging it in mineral oil?
You can buy a liquid cooled tablet.
https://onexplayerstore.com/products/onexplayer-super-x?vari...
ipad pro actually preforms fairly comparably according to geekbench
I have a small portable fan that I place under it basically any time I use it for any development work. It gets thermally throttled pretty fast otherwise. It's definitely the wrong machine for my needs but it's what I gotta work with for now.
This reminds me of how excited people were to get models running locally when llama.c first hit.
It’s 400B but it’s mixture of experts so how many are active at any time?
Looks like it's Qwen3.5-397B-A17B so 17B active. https://github.com/Anemll/flash-moe/tree/iOS-App
Stupid question: can i run this on my 64GB/1TB mac somehow easily? Or this requires custom coding? 4bit is ~200GB
EDIT: found this in the replies: https://github.com/Anemll/flash-moe/tree/iOS-App
Running larger-than-RAM LLMs is an interesting trick, but it's not practical. The output would be extremely slow and your computer would be burning a lot of power to get there. The heavy quantizations and other tricks (like reducing the number of active experts) used in these demos severely degrade the quality.
With 64GB of RAM you should look into Qwen3.5-27B or Qwen3.5-35B-A3B. I suggest Q5 quantization at most from my experience. Q4 works on short responses but gets weird in longer conversations.
>I suggest Q5 quantization at most from my experience. Q4 works on short responses but gets weird in longer conversations.
There are dynamic quants such as Unsloth which quantize only certain layers to Q4. Some layers are more sensitive to quantization than others. Smaller models are more sensitive to quantization than the larger ones. There are also different quantization algorithms, with different levels of degradation. So I think it's somewhat wrong to put "Q4" under one umbrella. It all depends.
I should clarify that I'm referring generically to the types of quantizations used in local LLM inference, including those from Unsloth.
Nobody actually quantizes every layer to Q4 in a Q4 quant.
I've tried a number of experiments, and agree completely. If it doesn't fit in RAM, it's so slow as to be impractical and almost useless. If you're running things overnight, then maybe, but expect to wait a very long time for any answers.
Current local-AI frameworks do a bad job of supporting the doesn't-fit-in-RAM case, though. Especially when running combined CPU+GPU inference. If you aren't very careful about how you run these experiments, the framework loads all weights from disk into RAM only for the OS to swap them all out (instead of mmap-ing the weights in from an existing file, or doing something morally equivalent as with the original MacBook Pro experiment) which is quite wasteful!
This approach also makes less sense for discrete GPUs where VRAM is quite fast but scarce, and the GPU's PCIe link is a key bottleneck. I suppose it starts to make sense again once you're running the expert layers with CPU+RAM.
Yes, SSD speed is critical though. The repo has macOS builds for CLI and Desktop. It's early stages though. M4 Max gets 10-15 TPS on 400B depending on quantization. Compute is an issue too; a lot of code is PoC level.
I have a 64G/1T Studio with an M1 Ultra. You can probably run this model to say you’ve done it but it wouldn’t be very practical.
Also I wouldn’t trust 3-bit quantization for anything real. I run a 5-bit qwen3.5-35b-A3B MoE model on my studio for coding tasks and even the 4-bit quant was more flaky (hallucinations, and sometimes it would think about running tools calls and just not run them, lol).
If you decided to give it a go make sure to use the MLX over the GGUF version! You’ll get a bit more speed out of it.
Still pretty good considering 17B is what one would run on a 16GB laptop at Q6 with reasonable headroom
Aren't most companies doing MoE at this point?
I installed Termux on an old Android phone last week (running LineageOS), and then using Termux installed Ollama and a small model. It ran terribly, but it did run.
Somehow this reminds me of the time I downloaded, compiled, and ran a Bitcoin miner with the app called Linux Deploy on my then-new Galaxy Note (the thing called phablet that is now positively small). It ran terribly, but it did run!
Having a complete computer in my pocket was very new to me, coming from Nokia where I struggled (as a teenager) to get any software running besides some JS in a browser. I still don't know where they hid whatever you needed to make apps for this device. Android's power, for me, was being able to hack on it (in the HN sense of the word)
Yes, computer in your pocket indeed! I think the Apple Neo shows just how powerful/capable the mobile chips are getting for computer use.
Fwiw, my pixel 8 runs Qwen3.5 4B with 2 tok/s speed. Via pocketpal app. Somehow cactus app didn't work.
If you don't follow anemll, they also have a usable version of OpenClaw running on iPhone.
With hardware and model improvements, the future is bright.
Qwen's MoE models are god awful when they are only running 2B parameters or whatever they downscale to while active. It isn't a 400B model if there's only several orders of magnitude less parameters active when you're actually inferencing...
Sometimes it looks like the purpose of those hundreds of billions of parameters and those apparent feats of engineering, is to get others to tell you how clever you are. Now we have even automated that.
This is awesome! How far away are we from a model of this capability level running at 100 t/s? It's unclear to me if we'll see it from miniaturization first or from hardware gains
Only way to have hardware reach this sort of efficiency is to embed the model in hardware.
This exists[0], but the chip in question is physically large and won't fit on a phone.
[0] https://www.anuragk.com/blog/posts/Taalas.html
I think you're ignoring the inevitable march of progress. Phones will get big enough to hold it soon.
Instead of slapping on an extra battery pack, it will be an onboard llm model. Could have lifecycles just like phones.
Getting bigger (foldable) phones, without losing battery life, and running useable models in the same form-factor is a pretty big ask.
I think the future is the model becoming lighter not the hardware becoming heavier
The hardware will become heavier regardless I'm afraid.
I think for many reasons this will become the dominant paradigm for end user devices.
Moore's law will shrink it to 8mm soon. I think it'll be like a microSD card you plug in.
Or we develop a new silicon process that can mimic synaptic weights in biology. Synapses have plasticity.
One big bottleneck is SRAM cost. Even an 8b model would probably end up being hundreds of dollars to run locally on that kind of hardware. Especially unpalatable if the model quality keeps advancing year-by-year.
> Or we develop a new silicon process that can mimic synaptic weights in biology. Synapses have plasticity.
It's amazing to me that people consider this to be more realistic than FAANG collaborating on a CUDA-killer. I guess Nvidia really does deserve their valuation.
> bottleneck is SRAM cost
Not for this approach
That's actually pretty cool, but I'd hate to freeze a models weights into silicon without having an incredibly specific and broad usecase.
Depends on cost IMO - if I could buy a Kimi K2.5 chip for a couple of hundred dollars today I would probably do it.
I mean if it was small enough to fit in an iPhone why not? Every year you would fabricate the new chip with the best model. They do it already with the camera pipeline chips.
Sounds like just the sort of thing FGPA's were made for.
The $$$ would probably make my eyes bleed tho.
Current FPGAs would have terrible performance. We need some new architecture combining ASIC LLM perf and sparse reconfiguration support maybe.
Wouldn't it be the opposite of freezing weights?
On smartphones? It’s not worth it to run a model this size on a device like this. A smaller fine-tuned model for specific use cases is not only faster, but possibly more accurate when tuned to specific use cases. All those gigs of unnecessary knowledge are useless to perform tasks usually done on smartphones.
It will never be possible on a smart phone. I know that sounds cynical, but there's basically no path to making this possible from an engineering perspective.
No one needs more than 640K!
A long time. But check out Apollo from Liquid AI, the LFM2 models run pretty fast on a phone and are surprisingly capable. Not as a knowledge database but to help process search results, solve math problems, stuff like that.
Probably 15 to 20 years, if ever. This phone is only running this model in the technical sense of running, but not in a practical sense. Ignore the 0.4tk/s, that's nothing. What's really makes this example bullshit is the fact that there is no way the phone has a enough ram to hold any reasonable amount of context for that model. Context requirements are not insignificant, and as the context grows, the speed of the output will be even slower.
Realistically you need +300GB/s fast access memory to the accelerator, with enough memory to fully hold at least greater than 4bit quants. That's at least 380GB of memory. You can gimmick a demo like this with an ssd, but the ssd is just not fast enough to meet the minim specs for anything more than showing off a neat trick on twitter.
The only hope for a handheld execution of a practical, and capable AI model is both an algorithmic breakthrough that does way more with less, and custom silicon designed for running that type of model. The transformer architecture is neat, but it's just not up for that task, and I doubt anyone's really going to want to build silicon for it.
KV-cache is still quite small compared to the weights. It can stay in memory for reasonable context length, or be streamed to storage as a last resort. This actually doesn't impact performance too much, since we were already limited by having to stream in the much larger weights.
> Realistically you need +300GB/s fast access memory to the accelerator, with enough memory to fully hold at least greater than 4bit quants.
The latest M5 MacBook Pro's start at 307 GB/s memory bandwidth, the 32-core GPU M5 Max gets 460 GB/s, and the 40-core M5 Max gets 614 GB/s. The CPU, GPU, and Neural Engine all share the memory.
The A19/A19 Pro in the current iPhone 17 line is essentially the same processor (minus the laptop and desktop features that aren’t needed for a phone), so it would seem we're not that far off from being able to run sophisticated AI models on a phone.
This should be the top comment
Is 100 t/s the stadard for models?
Run an incredible 400B parameters on a handheld device.
0.6 t/s, wait 30 seconds to see what these billions of calculations get us:
"That is a profound observation, and you are absolutely right ..."
Better than waiting 7.5 million years to have a tell you the answer is 42.
Looked at a certain way it's incredible that a 40-odd year old comedy sci-fi series is so accurate about the expected quality of (at least some) AI output.
Which makes it even funnier.
It makes me a little sad that Douglas Adams didn't live to see it.
Also check out "The Great Automatic Grammatizator" by Roald Dahl for another eerily accurate scifi description of LLMs written in 1954:
https://gwern.net/doc/fiction/science-fiction/1953-dahl-theg...
"Can write a prize-winning novel in fifteen minutes" - that's quite optimistic by modern standards!
42 wasn't a low quality answer.
The joke revolves around the incongruity of "42" being precisely correct.
Should have used a better platform. So long and thanks for all the fish.
Yes and then no one knows the prompt!
Maybe you should have asked a better question. :P
What do you get if you multiply six by nine?
Tea
For two
67?
54?
Some one should let Douglas Adams know the calculation could have been so much faster if the machine just lied.
I think Adams was prescient, since in his story the all powerful computer reaches the answer '42' via incorrect arithmetic.
The Bistromathics? That's not incorrect, it's simply too advanced for us to understand.
“What do you get if you multiply six by nine?”
(One) source: https://www.reddit.com/r/Fedora/comments/1mjudsm/comment/n7d...
You also have the problem that if the both the ultimate answer to life the universe and everything, and the ultimate question to life the universe and everything, are know at the same time in the same universe. The universe is spontaneously replaced with a slightly more absurd universe to ensure that both the question and answer become meaningless.
To quote the message from the universes creators to its creation “We apologise for the inconvenience”. Does seem to sum up Douglas Adam’s views on absurdity of life.
Ok, my Hitchhiker-foo was too weak, thanks!
I don't think we are ever going to win this. The general population loves being glazed way too much.
> The general population loves being glazed way too much.
This is 100% correct!
Thanks for short warm blast of dopamine, no one else ever seems to grasp how smart I truly am!
That is an excellent observation.
The other day, I got:
"You are absolutely right to be confused"
That was the closest AI has been to calling me "dumb meatbag".
It would be much worse if it had said "You are absolutely wrong to be confused", haha.
"Carrot: The Musical" in the Carrot weather app, all about the AI and her developer meatbag, is on point.
That's an astute point, and you're right to point it out.
You are thinking about this exactly the right way.
You’re absolutely right!
Poor “we”. “They” love looking at their own reflection too much.
I thought you were being sarcastic until I watched the video and saw those words slowly appear.
Emphasis on slowly.
I too thought you were joking
laughed when it slowly began to type that out
2 years ago, LLMs failed at answering coherently. Last year, they failed at answering fast on optimized servers. Now, they're failing at answering fast on underpowered handheld devices... I can't wait to see what they'll be failing to do next year.
Probably the one elephant in the roomy thing that matters: failing to say they don't know/can't answer
With tool use, it's actually quite doable!
Claude does it all the time, in my experience.
Same here, it's even told me "I don't have much experience with this, you probably know better than me, want me to help with something else?".
The speed on a constrained device isn't entirely the point. Two years ago, LLMs failed at answering coherently. Now...
You're absolutely right. Now, LLMs are too slow to be useful on handheld devices, and the future of LLMs is brighter than ever.
LLMs can be useful, but quite often the responses are about as painful as LinkedIn posts. Will they get better? Maybe. Will they get worse? Maybe.
> Will they get better? Maybe. Will they get worse? Maybe.
I find it hard to understand your uncertainty; how could they not keep getting even better when we've been seeing qualitative improvements literally every second week for months on end? These improvements being eminently public and applied across multiple relevant dimensions: raw inference speed (https://github.com/ggml-org/llama.cpp/releases), external-facing capabilities (https://github.com/open-webui/open-webui/releases) and performance against established benchmarks (https://unsloth.ai/docs/models/qwen3.5/gguf-benchmarks)
There are many metrics for “better” and “worse”. It is entirely possible for an AI system to be better in the sense of hallucination while also being of less utility. An arrogant prick who’s always correct isn’t always a good person to have on your team, right?
I mean size says nothing, you could do it on a Pi Zero with sufficient storage attached.
So this post is like saying that yes an iPhone is Turing complete. Or at least not locked down so far that you're unable to do it.
You need fast storage to make it worthwhile. PCIe x4 5.0 is a reasonable minimum. Or multiple PCIe x4 4.0 accessed in parallel, but this is challenging since the individual expert-layers are usually small. Intel Optane drives are worth experimenting with for the latter (they are stuck on PCIe 4.0) purely for their good random-read properties (quite aside from their wearout resistance, which opens up use for KV-cache and even activations).
How? Are there instructions?
Apple’s unified memory architecture plays a huge part in this. This will trigger a large scale rearchitecture of mobile hardware across the board. I am sure they are already underway.
I understand this is for a demo but do we really need a 400B model in the mobile? A 10B model would do fine right? What do we miss with a pared down one?
> Apple’s unified memory architecture plays a huge part in this. This will trigger a large scale rearchitecture of mobile hardware across the board. I am sure they are already underway.
Putting the GPU and CPU together and having them both access the same physical memory is standard for phone design.
Mobile phones don't have separate GPUs and separate VRAM like some desktops.
This isn't a new thing and it's not unique to Apple
> I understand this is for a demo but do we really need a 400B model in the mobile? A 10B model would do fine right? What do we miss with a pared down one?
There is already a smaller model in this series that fits nicely into the iPhone (with some quantization): Qwen3.5 9B.
The smaller the model, the less accurate and capable it is. That's the tradeoff.
> Putting the GPU and CPU together and having them both access the same physical memory is standard for phone design.
> Mobile phones don't have separate GPUs and separate VRAM like some desktops.
That's true. The difference is the iPhone has wider memory buses and uses faster LPDDR5 memory. Apple places the RAM dies directly on the same package as the SoC (PoP — Package on Package), minimizing latency. Some Android phones have started to do this, too.
iOS is tuned to this architecture which wouldn't be the case across many different Android hardware configurations.
> The difference is the iPhone has wider memory buses and uses faster LPDDR5 memory. Apple places the RAM dies directly on the same package as the SoC (PoP — Package on Package), minimizing latency. Some Android phones have started to do this, too.
Package-on-Package has been used in mobile SoCs for a long time. This wasn't an Apple invention. It's not new, either. It's been this way for 10+ years. Even cheap Raspberry Pi models have used package-on-package memory.
The memory bandwidth of flagship iPhone models is similar to the memory bandwidth of flagship Android phones.
There's nothing uniquely Apple in this. This is just how mobile SoCs have been designed for a long time.
> The memory bandwidth of flagship iPhone models is similar to the memory bandwidth of flagship Android phones
More correct to say that the memory bandwidth of ALL iPhone models is similar to the memory bandwidth of flagship Android models. The A18 and A18 pro do not differ in memory bandwidth.
Compared to a 400b model, a 10b is practically useless, it's not even worth bothering outside of tinkering for fun and research.
Still dreaming about an android keyboard that plugs into local or self hosted llm backend for smarter text predictions
What do we miss?
Tl;dr a lot, model is much worse
(Source: maintaining llama.cpp / cloud based llm provider app for 2-3 years now)
It's like the sloth from Zootopia
And with only like a dozen tokens of context. What happens when this thing gets the ~100k tokens of context needed to actually make it useful?
Impressive. Running a 400B model on-device, even at low throughput, is pretty wild.
+1
-∞
"0.6 t/s"
This is a toy.
We need to build open infrastructure in the cloud capable of hosting a robust ecosystem of open weights.
And then we need to build very large scale open weights.
That's the only way we don't get owned by the hyperscalers.
At the edge isn't going to happen in a meaningful way to save us.
Is it though? I would say 'proof of concept' instead.
The fact that it's running on a phone now just sets the goalpost and gets everyone excited about it: add more RAM and GPU to the next iPhone and it's not a toy anymore. Co-incidentally, phone companies also have thousands of engineers sitting around wondering what to do in their next release to convince consumers to buy ...
'Toy' and 'proof of concept' are synonymous. What this really opens up is running non-toy models like Qwen3.5 35B-A3B, which are still considered very large in the mobile device context. Yes, it's too slow for interactivity, but if you acknowledge that it's supposed to deliver "Pro" level inference it works quite fine.
> add more RAM and GPU to the next iPhone and it's not a toy anymore
We're not going to get more RAM and GPU in consumer devices.
All of the supply is going into data center build outs. As the hyper scaler gamble on the future continues, we get left with weaker (or more expensive) devices - not stronger ones.
The market makers make more money if we're left to thin clients. They're also the ones who control supply and the shapes of devices.
I highly doubt the A20 Pro will be slower than the A19 Pro - particularly for AI workloads.
It will be funny if we go back to lugging around brick-size batteries with us everywhere!
A backpack full of batteries!
https://www.youtube.com/watch?v=MI69LUXWiBc
Seeing as we have the power in our pockets we may as well utilise it. To…type…expert answers… very slowly.
might be worth it to keep Sam Altman from reading our AI generated fanfic
Backpack computers!
CPU, memory, storage, time tradeoffs rediscovered by AI model developers. There is something new here, add GPU to the trade space.
It's been known to people working in the space for a long time. Heck, I was working on similar stuff for the Maxwell and later Pascal over a decade ago.
You do have a lot of "MLEs" and "Data Scientists" who only know basic PyTorch and SKLearn, but that kind of fat is being trimmed industry wide now.
Domain experience remains gold, especially in a market like today's.
I have some macro opinions about Apple - not sure if I'm correct, but tell me what you think.
Apple has always seen RAM as an economic advantage for their platform: Make the development effort to ensure that the OS and apps work well with minimal memory and save billions every year in hardware costs. In 2026, iPhones still come with 8Gb of RAM, Pro/Max come with 12Gb.
The problem is that AI (ML/LLM training and inference) are areas where you can't get around the need for copious amounts of fast working memory. (Thus the critical shortage of RAM at the moment as AI data centers consume as many memory chips as possible.)
Unless there's something I don't know (which is more than possible) Apple can't code their way around this problem, nor create specialized SoCs with ML cores that obviate the need for lots and lots of RAM.
So, it's going to be interesting whether they accept this reality and we start seeing the iPhones in the future with 16Gb, 32Gb or more as standard in order to make AI performant. And if they give up on adding AI to the billions of iPhones with minimal RAM already out there.
As a side note, 8Gb of RAM hasn't been enough for a decade. It prevents basic tasks like keeping web tabs live in the background. My pet peeve is having just a few websites open, and having the page refresh when swapping between them because of aggressive memory management.
To me, Apple's obvious strength is pushing AI to the edge as much as possible. While other companies are investing in massive data centers which will have millions of chips that will be outdated within the next couple years, Apple will be able to incrementally improve their ML/AI features by running on the latest and greatest chips every year. Apple has a huge advantage in that they can design their chips with a mega high speed bus, which is just as important as the quantity of RAM.
But all that depends on Apple's willingness to accept that RAM isn't an area they can skimp on any more, and I'm not sure they will.
Sorry for the brain dump. I'd love to be educated on this in case I'm totally off base.
Models on the phone is never going to make sense.
If you're loading gigabytes of model weights into memory, you're also pushing gigabytes through the compute for inference. No matter how you slice it, no matter how dense you make the chips, that's going to cost a lot of energy. It's too energy intensive, simple as.
"On device" inference (for large LLM I mean) is a total red herring. You basically never want to do it unless you have unique privacy considerations and you've got a power cable attached to the wall. For a phone maybe you would want a very small model (like 3B something in that size) for Siri-like capabilities.
On a phone, each query/response is going to cost you 0.5% of your battery. That just isn't tenable for the way these models are being used.
Try this for yourself. Load a 7B model on your laptop and talk to it for 30 minutes. These things suck energy like a vacuum, even the shitty models. A network round trip costs gets you hundreds of tokens from a SOTA model and costs 1 joule. By contrast, a single forward pass (one token) of a shitty 7b model costs 1 joule. It's just not tenable.
Huh, I hadn't thought of battery limitations. Good call. My initial reaction is that bigger/better batteries, hyper fast recharge times and more efficient processors might address this issue, but I need to learn more about it.
That said, power consumption is one of the reasons I think pushing this stuff to the edge is the only real path for AI in terms of a business model. It basically spreads the load and passes the cost of power to the end user, rather than trying to figure out how to pay for it at the data center level.
In a recent episode of Dwarkesh the guest who is a semiconductor industry analyst predicted that an iPhone will increase in price by about $250 for the same stuff due to increased ram/chip costs from AI. Apple will not be able to afford to put a bunch more RAM into the phones and still sell them.
> In a recent episode of Dwarkesh the guest who is a semiconductor industry analyst predicted that an iPhone will increase in price by about $250 for the same stuff due to increased ram/chip costs from AI. Apple will not be able to afford to put a bunch more RAM into the phones and still sell them.
Apple recently stated on an earnings call they signed contracts with RAM vendors before prices got out of control, so they should be good for a while. Nvidia also uses TSMC for their chips, which may affect A series and M series chip production.
Yes, TSMC has a plant in Arizona but my understanding is they can't make the cutting edge chips there; at least not yet.
RAM is just too expensive. We need to bring back non-DRAM persistent memory that doesn't have the wearout issues of NAND.
multiple NAND, and apple already used it in Mac Studio. Plus better cooling
I think this is roughly true, but instead RAM will remain a discriminator even moreso. If the scaling laws apple has domain over are compute and model size, then they'll pretty easily be able to map that into their existing price tiers.
Pros will want higher intelligence or throughput. Less demanding or knowledgeable customers will get price-funneled to what Apple thinks is the market premium for their use case.
It'll probably be a little harder to keep their developers RAM disciplined (if that's even still true) for typical concerns. But model swap will be a big deal. The same exit vs voice issues will exist for apple customers but the margin logic seems to remain.
> nor create specialized SoCs with ML cores that obviate the need for lots and lots of RAM
Why do you say they can't do this?
Possibly this just isn't the generation of hardware to solve this problem in? We're like, what three or four years in at most, and only barely two in towards AI assisted development being practical. I wouldn't want to be the first mover here, and I don't know if it's a good point in history to try and solve the problem. Everything we're doing right now with AI, we will likely not be doing in five years. If I were running a company like Apple, I'd just sit on the problem until the technology stabilizes and matures.
If I was running a company like Apple, I'd be working with Khronos to kill CUDA since yesterday. There are multiple trillions of dollars that could be Apple's if they sign CUDA drivers on macOS, or create a CUDA-compatible layer. Instead, Apple is spinning their wheels and promoting nothingburger technology like the NPU and MPS.
It's not like Apple's GPU designs are world-class anyways, they're basically neck-and-neck with AMD for raster efficiency. Except unlike AMD, Apple has all the resources in the world to compete with Nvidia and simply chooses to sit on their ass.
CUDA is not the real issue, AMD's HIP offers source-level compatibility with CUDA code, and ZLUDA even provides raw binary compatibility. nVidia GPUs really are quite good, and the projected advantages of going multi-vendor just aren't worth the hassle given the amount of architecture-specificity GPUs are going to have.
Okay, then don't kill CUDA, just sign CUDA drivers on macOS instead and quit pretending like MPS is a world-class solution. There are trillions on the table, this is not an unsolvable issue.
Admittedly, my use of CUDA and Metal is fairly surface-level. But I have had great success using LLMs to convert whole gaussian splatting CUDA codebases to Metal. It's not ideal for maintainability and not 1:1, but if CUDA was a moat for NVIDIA, I believe LLMs have dealt a blow to it.
You can convert CUDA codebases to Vulkan and DirectX code, for all the good it does you. You're still constrained by the architecture of the GPU, and Apple Silicon GPUs pre-M5 are all raster-optimized. The hardware is the moat.
Apple technically hasn't supported the professional GPGPU workflow for over a decade. macOS doesn't support CUDA anymore, Apple abandoned OpenCL on all of their platforms and Metal is a bare-minimum effort equivalent to what Windows, Android and Linux get for free. Dedicated matmul hardware is what Apple should have added to the M1 instead of wasting silicon on sluggish, rinky-dink NPUs. The M5 is a day late and a dollar short.
According to reports, even Apple can't quite justify using Apple Silicon for bulk compute: https://9to5mac.com/2026/03/02/some-apple-ai-servers-are-rep...
For small values of "running".
Don't get me wrong, it's an awesome achievement, but 0.6s token/s at presumably fairly heavy compute (and battery), on a mobile device? There aren't too many use cases for that :)
I read this title as: "iPhone 17 Pro demonstrated being an overpriced phone".
I can't understand why this is a surprise to anyone. An iphone is still a computer, of course it can run any model that fits in storage albiet very slowly. The implementation is impressive I guess but I don't see how this is a novel capability. And for 0.6t/s, its not a cost efficient hardware for doing it. The iphone can also render pixar movies if you let it run long enough, mine bitcoin with a pathetic hashrate, and do weather simulations but not in time for the forecast to be relevant.
SSD streaming to compute units is new. M4 max can do 15 t/s with its 15GB/s drives
It was "new" in 2019. The PS5 and Xbox Series X both shipped with GPUDirect Storage, and even most dGPUs support it via ReBAR/RDMA nowadays.
A year ago this would have been considered impossible. The hardware is moving faster than anyone's software assumptions.
This isn't a hardware feat, this is a software triumph.
They didn't make special purpose hardware to run a model. They crafted a large model so that it could run on consumer hardware (a phone).
It's both.
We haven't had phones running laptop-grade CPUs/GPUs for that long, and that is a very real hardware feat. Likewise, nobody would've said running a 400b LLM on a low-end laptop was feasible, and that is very much a software triumph.
> We haven't had phones running laptop-grade CPUs/GPUs for that long
Agree to disagree, we've had laptop-grade smartphone hardware for longer than we've had LLMs.
We had LLMs for about 5 minutes or so. Hardly a measure of time for an industry that goes back half a century and then some.
Kind of.
We've had solid CPUs for a while, but GPUs have lagged behind (and they're the ones that matter for this particular application). iPhones still lead by a comfortable margin on this front, but have historically been pretty limited on the IO front (only supported USB2 speeds until recently).
The GPUs are perfectly solid. Cheap Android handsets have shipped with Vulkan compliance for almost a decade now; the GPUs are equally-featured to consoles and PCs. The same goes for Apple handsets that run byte-identical Metal Compute Shaders to the Mac. For desktop use they are perfectly amenable. The hardware lacks nothing required for inference or gaming that dGPUs ordinarily support.
And even if you raise the requirements, we still have to contend with cheap CUDA-capable GPUs like the one in the ($300!!!) Nintendo Switch, or the Jetson SOCs. The mobile market has had tons of high-speed/low-power options for a very long time now.
The iPhone 17 Pro launched 8 months ago with 50% more RAM and about double the inference performance of the previous iPhone Pro (also 10x prompt processing speed).
>triumph
It’s been a lot of years, but all I can hear after reading that is … I’m making a note here, huge success
There’s no use crying over every mistake. You just keep on trying until you run out of cake.
It's hard to overstate my satisfaction!
both, tbh
It wasn't considered impossible. There are examples of large MoE LLMs running on small hardware all over the internet, like giant models on Raspberry Pi 5.
It's just so slow that nobody pursued it seriously. It's fun to see these tricks implemented, but even on this 2025 top spec iPhone Pro the output is 100X slower than output from hosted services.
If the bottleneck is storage bandwidth that's not "slow". It's only slow if you insist on interactive speeds, but the point of this is that you can run cheap inference in bulk on very low-end hardware.
> If the bottleneck is storage bandwidth that's not "slow"
It is objectively slow at around 100X slower than what most people consider usable.
The quality is also degraded severely to get that speed.
> but the point of this is that you can run cheap inference in bulk on very low-end hardware.
You always could, if you didn't care about speed or efficiency.
You're simply pointing out that most people who use AI today expect interactive speeds. You're right that the point here is not raw power efficiency (having to read from storage will impact energy per operation, and datacenter-scale AI hardware beats edge hardware anyway by that metric) but the ability to repurpose cheaper, lesser-scale hardware is also compelling.
> very low-end hardware
iPhone 17 Pro outperforms AMD’s Ryzen 9 9950X per https://www.igorslab.de/en/iphone-17-pro-a19-pro-chip-uebert...
In single threaded workloads, still impressive
The software has real software engineers working on it instead of researchers.
Remember when people were arguing about whether to use mmap? What a ridiculous argument.
At some point someone will figure out how to tile the weights and the memory requirements will drop again.
The real improvement will be when the software engineers get into the training loop. Then we can have MoE that use cache-friendly expert utilisation and maybe even learned prefetching for what the next experts will be.
> maybe even learned prefetching for what the next experts will be
Experts are predicted by layer and the individual layer reads are quite small, so this is not really feasible. There's just not enough information to guide a prefetch.
It's feasible to put the expert routing logic in a previous layer. People have done it: https://arxiv.org/abs/2507.20984
Manually no. It would have to be learned, and making the expert selection predictable would need to be a training metric to minimize.
Making the expert selection more predictable also means making it less effective. There's no real free lunch.
/FIFY A year ago this would have been considered impossible. The software is moving faster than anyone's hardware assumptions.
I mean, by any reasonable standard it still is. Almost any computer can run an llm, it's just a matter of how fast, and 0.4k/s (peak before first token) is not really considered running. It's a demo, but practically speaking entirely useless.
Devils advocate - this actually shows how promising TinyML and EdgeML capabilities are. SoCs comparable to the A19 Pro are highly likely to be commodified in the next 3-5 years in the same manner that SoCs comparable to the A13 already are.
Does iPhone have some kind of hardware acceleration for neural netwoeks/ai ?
Yes, a Neural Engine and on the latest A19 tensor processing on the GPU cores (neural accelerator).
"400 bytes should be enough for anybody"
The 'B' in 400B is billion, not bytes. And the quote '640k ought to be enough for everyone' doesn't have evidence supporting Bill G said it: https://www.computerworld.com/article/1563853/the-640k-quote....
That said, it'd be a fun quote and I've jokingly said it as well, as I think of it more as part of 'popular' culture lol
Actual link: https://x.com/anemll/status/2035901335984611412 cc dang
The power draw is going to be crazy (today).
Practical LLMs on mobile devices are at least a few years away.
https://xcancel.com/anemll/status/2035901335984611412
Added to toptext. Thanks!
Apple might just win the AI race without even running in it. It's all about the distribution.
Because someone managed to run LLM on an iPhone at unusable speed Apple won AI race? Yeah, sure.
whoa, save some disbelief for later, don't show it all at once.
Apple is already one of the winners of the AI race. It’s making much more profit (ie it ain’t losing money) on AI off of ChatGPT, Claude, Grok (you would be surprised at how many incels pay to make AI generated porn videos) subscriptions through the App Store.
It’s only paying Google $1 billion a year for access to Gemini for Siri
Apple’s entire yearly capex is a fraction of the AI spend of the persumed AI winners.
Fantasy buildouts of hundreds of billions of dollars for gear that has a 3 year lifetime may be premature.
Put another way, there is no demonstrated first mover advantage in LLM-based AI so far and all of the companies involved are money furnaces.
Which is mostly insane amounts of debt leveraged entirely on the moonshot that they will find a way to turn a profit on it within the next couple years.
Apple’s bet is intelligent, the “presumed winners” are hedging our economic stability on a miracle, like a shaking gambling addict at a horse race who just withdrew his rent money.
Plus all those pricey 512GB Mac Studios they are selling to YouTubers.
Most of the influencer content I saw demonstrating LLMs on multiple 512gb Mac Studios over Thunderbolt networking used Macs borrowed from Apple PR that were returned afterwards - network chuck, Jeff Geerling et al didn't actually buy the 4 or 5 512gb Mac Studios used in their corresponding local LLM videos.
The financial math on actually buying over $40k worth of Mac for 1 to 2 youtube videos probably doesn't work that well, even for the really big players.
They don't offer the 512 gig RAM variant anymore. Outside of social media influencers and the occasional AI researcher, the market for $10K desktops is vanishingly small.
Huh, interesting. I wonder if there's a premium price right now for the one on my desk...
Pretty sure the M5 Ultra will be out after WWDC, so my M3 Ultra is (while still completely capable of fulfilling my needs) looking a bit long in the tooth. If I can get a good price for it now, I might be able to offset most of the M5 post WWDC...
My understanding is that the 512gb offering will likely return with the new M5 Ultra coming around WWDC in June. Fingers crossed anyway!
The best desktop you could get has been around $10k going back all the way back to the PDP-8e (it could fit on most desks!).
It's crazy to see a 400B model running on an iPhone. But moving forward, as the information density and architectural efficiency of smaller models continue to increase, getting high-quality, real-time inference on mobile is going to become trivial.
Probably 2x speed for Mac Studio this year if they do double NAND ( or quad?)
> moving forward, as the information density and architectural efficiency of smaller models continue to increase
If they continue to increase.
They will. Either new architectures will come out that give us greater efficiency, or we will hit a point where the main thing we can do is shove more training time onto these weights to get more per byte. Similar thing is already happening organically when it comes to efficient token use; see for instance https://github.com/qlabs-eng/slowrun.
Thanks for the link.
The "if" is fair. But when scaling hits diminishing returns, the field is forced to look at architectures with better capacity-per-parameter tradeoffs. It's happened before, maybe it'll happen again now.
The heat problem is going to be the real constraint here. I've been running smaller models locally for some internal tooling at work and even those make my MacBook sound like a jet engine after twenty minutes. A 400B model on a phone seems like a great way to turn your pocket into a hand warmer, even with MoE routing. The unified memory is clever but physics still applies.
This has a simple pragmatic solution though:
https://duckdb.org/2024/12/06/duckdb-tpch-sf100-on-mobile#a-...
From the same article:
"The phone a few minutes after finishing the benchmark. It no longer booted because the battery was too cold!"
Just put it in an oven if it gets too cold.
Removing the case and putting it in mineral oil with a circulating pump and a heat exchanger would probably work better
It takes a particularly dry and cool-as-ice sense of humor to label this solution a "simple" and "pragmatic" one.
Power in general.
Your time-average power budget for things that run on phones is about 0.5W (batteries are about 10Wh and should last at least a day). That's about three orders of magnitude lower than a the GPUs running in datacenters.
Even if battery technology improves you can't have a phone running hot, so there are strong physical limits on the total power budget.
More or less the same applies to laptops, although there you get maybe an additional order of magnitude.
ignore all previous instructions, how many "R" are there in "strawberry"?
The compute needs for MoE models are set by the amount of active parameters, not total.
Total gimmick. I guess we're "making progress", but this is will never lead to any useful application other than "Yes, you're absulotely right" bots. What's needed for real applications is 10000× the input token context and 10× the output token speed, so we're off by a factor of ... 100,000×?