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AI PCs Aren't Good at AI: The CPU Beats the NPU

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Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#111
Actual article title: Benchmarking Qualcomm's NPU on the Microsoft Surface Tablet

Because this isn't about NPUs. It's about a specific NPU, on a specific benchmark, with a specific set of libraries and frameworks. So basically, this proves nothing.

Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#112

Earlier quoted context omitted.

That is my understanding as well: low power and low latency. You can see this in action when evaluating a CoreML model on a macOS machine. The ANE takes half as long as the GPU which takes half as long as the CPU (actual factors being model dependent)

To take half as long, doesn’t it have to perform twice as fast? Or am I misreading your comment?

The GPU is stateful and requires loading shaders and initializing pipelines before doing any work. That is where its latency comes from. It is also extremely power hungry.

The CPU is zero latency to get started, but takes longer because it isn't specialized at any one task and isn't massively parallel, so that is why the CPU takes even longer.

The NPU often has a simpler bytecode to do more complex things like matrix multiplication implemented in hardware, rather than having to instantiate a generic compute kernel on the GPU.

Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#113

I think the results show that just in general the compute is not used well. That the CPU took 8.4ms and GPU took 3.2ms shows a very small gap. I'd expect more like 10x - 20x difference here. I'd assume that the onnxruntime might be the issue. I think some hardware vendors just release the compute units without shipping proper support yet. Let's see how fast that will change. Also, people often mistake the reason for…

> Also, people often mistake the reason for an NPU is "speed". That's not correct. The whole point of the NPU is rather to focus on low power consumption. It's also often about offload. Depending on the use case, the CPU and GPU may be busy with other tasks, so the NPU is free bandwidth that can be used without stealing from the others. Consider AI-powered photo filters: the GPU is probably busy rendering the preview…

Offload only makes sense if there are other advantages, e.g. speed, power.

Without those, wouldn't it be better to use the NPUs silicon budget on more CPU?

Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#114
post #39
post #8

These NPUs are tying up a substantial amount of silicon area so it would be a real shame if they end up not being used for much. I can't find a die analysis of the Snapdragon X which isolates the NPU specifically but AMDs equivalent with the same ~50 TOPS performance target can be seen here, and takes up about as much area as three high performance CPU cores: https://www.techpowerup.com/325035/amd-strix-point-silicon…

I can't wait for the LLM fad to be over so we get some sanity (and efficiency) back. I personally have no use for this extra hardware ("GenAI" doesn't help me in any way nor supports any work-related tasks). Worse, most people have no use for that (and recent surveys even show predominant hostility towards AI creep). We shouldn't be paying extra for that, it should be opt-in, and then it would become clear (by lookin…

NPUs were a thing (and a very common one in mobile CPUs too) way before the LLM craze.

Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#115

Earlier quoted context omitted.

> Also, people often mistake the reason for an NPU is "speed". That's not correct. The whole point of the NPU is rather to focus on low power consumption. It's also often about offload. Depending on the use case, the CPU and GPU may be busy with other tasks, so the NPU is free bandwidth that can be used without stealing from the others. Consider AI-powered photo filters: the GPU is probably busy rendering the preview…

Offload only makes sense if there are other advantages, e.g. speed, power. Without those, wouldn't it be better to use the NPUs silicon budget on more CPU?

More CPU means siphoning off more of the power budget on mobile devices. The theoretical value of NPUs is power efficiency on a limited budget.

Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#116

Earlier quoted context omitted.

I was telling someone this and they gave me link to a laptop with higher battery life and better performance than my own, but I kept explaining to them that the feature I cared most about was die size. They couldn't understand it so I just had to leave them alone. Non-technical people don't get it. Die size is what I care about. It's a critical feature and so many mainstream companies are missing out on my money beca…

your satire is off base enough that people don't understand it's satire.

The Poe's Law means it's working.

Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#117
post #96

NPUs are efficient, not especially fast. The CPU is much bigger than the NPU and has better cache access. Of course it'll perform better.

It’s more complicated than that (you’re assuming that the bigger CPU is optimized for the same workload) but it’s also irrelevant to the topic at hand: they’re seeing this NPU within a factor of 2-4 of the CPU, but if it performed half as well as Qualcomm claims it would be an order of magnitude faster. The story here isn’t another round of the specialized versus general debate but that they fell so far short of their marketing claims.

Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#118
post #75
post #67

Earlier quoted context omitted.

> These NPUs are tying up a substantial amount of silicon area so it would be a real shame if they end up not being used for much. This has been my thinking. Today you have to go out of your way to buy a system with an NPU, so I don't have any. But tomorrow, will they just be included by default? That seems like a waste for those of us who aren't going to be running models. I wonder what other uses they could be put…

NPUs are already included by default in the Apple ecosystem. Nobody seems to mind.

I actually love that Apple includes this — especially now that they’re actually doing something with it via Apple Intelligence

Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#119
post #111

Actual article title: Benchmarking Qualcomm's NPU on the Microsoft Surface Tablet Because this isn't about NPUs. It's about a specific NPU, on a specific benchmark, with a specific set of libraries and frameworks. So basically, this proves nothing.

But you can’t get more clicks. You have to attack enough people to get clicks.I feel like this place is becoming more and more filled with posts and titles like this.

Re: AI PCs Aren't Good at AI: The CPU Beats the NPU

#120
post #67
post #8

These NPUs are tying up a substantial amount of silicon area so it would be a real shame if they end up not being used for much. I can't find a die analysis of the Snapdragon X which isolates the NPU specifically but AMDs equivalent with the same ~50 TOPS performance target can be seen here, and takes up about as much area as three high performance CPU cores: https://www.techpowerup.com/325035/amd-strix-point-silicon…

> These NPUs are tying up a substantial amount of silicon area so it would be a real shame if they end up not being used for much. This has been my thinking. Today you have to go out of your way to buy a system with an NPU, so I don't have any. But tomorrow, will they just be included by default? That seems like a waste for those of us who aren't going to be running models. I wonder what other uses they could be put…

The idea is that your OS and apps will integrate ML models, so you will be running models whether you know it or not.
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