InferenceX DeepSeek v4 Performance Tracker
- Source
- newsletter.semianalysis.com
- Author
- Bryan Shan
- Date

Context
An accelerator's launch-day performance can change substantially as its serving software improves. SemiAnalysis's InferenceX tracker follows that process for DeepSeek v4. Its MI355X results moved from an initial higher-precision configuration to lower-precision model weights, specialized GPU code and tests with more simultaneous requests.
Those changes explain why the reported improvement cannot be read as a hardware-only comparison. They also distinguish two user experiences: producing more text across all customers and producing text faster for each customer. The tracker evaluates both, so a configuration suited to high aggregate demand need not be the best choice for a fast individual conversation.
- AMD's MI355X on day one could only run a non-native FP8 checkpoint and served 1-2 tokens per user per second — slower than people read. Technically working, practically unusable; kernel work made it 100x faster by day 26.
- AMD's ATOM engine had the hardcoded to a single sequence slot, so a second concurrent request had nowhere to store its state. Effective batch size: one user, no matter the hardware.
- Nvidia's own TensorRT- stumbled on the model and SemiAnalysis had to patch its kernel launch code. The open engines, vLLM and SGLang, ran the native checkpoint on release day without drama.
- via multi-token prediction landed on day 3 from SGLang and lifted throughput most at high interactivity, where small-batch decode is memory-bound rather than compute-bound.
- The CUDA moat shows up in distributed , not single-node: multi-node disaggregated prefill worked on GB200 at launch, and that recipe beat a B200 run by up to 5x at low-interactivity settings.
- inference — Running a trained model to get answers — the phase where AI is actually used, as opposed to trained.
- LLM — A large language model — the neural network behind tools like Claude and ChatGPT, trained on huge amounts of text to predict what comes next.
- KV cache — The memory a model keeps about text it has already read, so generating each new token doesn't require reprocessing the whole conversation.
- speculative decoding — A speed trick where a small model drafts several tokens ahead and the big model verifies them in one pass, often doubling generation speed.
“Huawei has proven it can sling a stone on Day 0; whether it can fell a moving giant is yet to be seen.”
“ATOM, by the way, currently has zero production customers.”
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