> I note the lack of performance information. I can only imagine it's much, much, slower than any other way to run a larger model (including, e.g. using system RAM and streaming some stuff from disk)
Not necessarily, and I suspect there are plenty of configuration for which this isn't going to be the case. Let me explain why:
- when offloading the weights to RAM or NVMe, you need to transfer the massive weights from your slow storage to the GPU for each layer being processed for each token. And as such you are being bottlenecked by the transfer bandwidth (which is either the men bandwidth of your DRAM or the read speed of your disk)
- when using a distributed setup, the weights stay in the VRAM on each machine, the it's the GPU memory bandwidth that matters for the weights, and it's much higher than the two other bandwidth discussed above and as such the bottleneck isn't here. You need to tranfert data from a group of layers sitting on one device to the next one another device, but the amount of data is much smaller than the weights (we're talking about kilobytes of data, not gigabytes) so the network throughput isn't a limiting factor.
The limiting factor is the network latency: if you split your model between 4 devices, you'll have 3 times the network latency per token. If you're on a network with 1ms latency, that means 3ms of latency per token. Which means the theoretical upper bound for your inference speed without speculative decoding is 30tps (this theoretical limit assumes the computation itself is instantaneous).
So this is unlikely to be practical over the internet (too high of a latency) but on a local/enterprise network with speculative decoding it could totally work.
Edit: note that all of the above is about token generation, for prefill/prompt-processing the distributed setup will almost certainly win (because in this case, the network latency doesn't add up)
I’m staring at this comment for a while now: With 3ms latency combined per token, wouldn’t that mean (1 / latency) = 333 token/s for the theoretical upper bound? I’m not trying to nitpick, just curious if I misunderstand something.
Indeed, I completely screwed my math up. Looks like 10am is too early in the morning for a Sunday.
33 tps max token generation speed would be for 10ms of network latency in the above example.
Ah, that's interesting. I though there was more data crossing the network. So, why does a DGX Spark come with super fast network if 10Gbps ethernet would be sufficient for splitting a model? I never bought a second Strix Halo on the assumption that the pipe between them would be a limiting factor to using larger models, so obviously there's something I don't understand.
The amount of data is only low for inference, not for training, and AFAIK DGX spark is supposed to be a researcher's machine that can do small-scale training.
This was done on my home lab simulating 5ms latency and jitter between machines. Splits work quite well if you your nodes are over WAN at metro latency’s but not super fast on global WAN.
The idea is that you could take several machines without dedicated RDMA or NVLINK fabric and use them to serve a large model on hardware you own then share it with others.
I’m currently working on GLM 5.2 on my lab environment with around 10 tok/s on the same split.
What hardware (CPU/GPU/memory) and network was used for this? What quantization for GLM 5.2? How much tuning of the split was needed?
The lab features two Mac Studios: an Apple M3 Ultra (32 CPU cores, 80 GPU cores, 256 GB unified memory) and an Apple M1 Ultra (20 CPU cores, 48 GPU cores, 128 GB unified memory), both connected via 1Gbit Ethernet.
We use a customized Q2 quantization that preserves sensitive tensors at Q8.
To reduce compute time per layer, we are developing a custom GLM DSA Metal graph.
While we are not yet approaching MTP, we plan to port our existing MTP implementations from versions 4.7 and 5.1 to 5.2.
Since GLM's MTP acceptance rate is very high for a single predicted token, we are exploring token prediction techniques to widen the predicted tokens and utilize parallelism for verification.
Equivalent M3 machines no longer for sale from Apple (only up to 96 GB) but can be had on eBay for around $14,000 each
It's notable that they're so valuable because they feature 800Gbps of memory bandwidth. About twice what's available on the top end of M5, and exactly what makes llm inference fast.
> because they feature 800Gbps of memory bandwidth. About twice what's available on the top end of M5
Ouch, about half of the memory bandwidth of a dedicated GPU though :/ Running LLMs on Apple hardware still doesn't make any sense to me.
M5 max has 614GB/s, you mean the m4?
That sounds cool, but it's still pretty meaningless without information about what your home lab looks like. A few DGX Sparks wired up with their fancy super fast network is much different than a few laptops on wifi.
Perf should be fairly straightforward to ballpark. You'll need to transfer roughly 2 . hidden_size . num_shards bytes over the network per token during autoregressive decoding. And divide that number by chunk size during prefill.
That's about the speed I get on a AMD Ryzen AI 9 HX 370 (inside a Framework 13), with Qwen3.6-35B-A3B, so doing the same on that much larger model...