Field guide / AI infrastructure
The language behind the inference curve.
Definitions for the metrics, serving techniques, numerical formats, and distributed systems concepts used across InferenceX. Based on measured behavior, not vendor peak specifications.
- Terms
- 48
- Categories
- 7
- Articles reviewed
- 14
48 terms
A
AI inference
Serving
You give a trained model something new, such as a prompt, image, or audio. It uses what it learned to produce an answer.
All-reduce
Parallelism
All-reduce lets every GPU solve one piece of a calculation, combines those pieces, and gives the combined result back to everyone.
All-to-all
Parallelism
All-to-all is a coordinated exchange where every GPU sends a different package of data to every other GPU.
B
C
Concurrency
Benchmark metrics
Concurrency is how many people or requests the system is serving at once.
Cost per million tokens
Benchmark metrics
This is the estimated infrastructure bill for producing one million tokens, the chunks of text an AI model reads and writes.
CUDA
Software
CUDA is NVIDIA’s software toolbox for making programs run on its GPUs.
D
Data parallelism
DPParallelism
Data parallelism makes multiple copies of the model and divides incoming work among them, like opening more identical checkout lanes.
Decode
Serving
Decode is the model writing its answer one token at a time after it has read the prompt.
Disaggregated inference
PD disaggregationServing
Disaggregated inference gives prompt reading and answer writing to separate GPU teams, so each team can be tuned for its own job.
E
EAGLE
Serving
EAGLE is a particular way to draft several likely next tokens for the main model to check, which can make answers stream faster.
Expert parallelism
EPParallelism
Expert parallelism gives different GPUs different specialist parts of a model, then sends each token to the specialists it needs.
F
FP4
Numerical precision
FP4 compresses model numbers into just 4 bits. That can make inference much faster and smaller, but leaves less room for numerical detail.
FP8
Numerical precision
FP8 is a compact 8-bit way to store and calculate with model numbers, reducing memory use and often speeding up inference.
H
I
Inference engine
Serving
The inference engine is the traffic controller behind an AI service: it keeps incoming requests moving and makes sure the GPUs do the right work at the right time.
Input and output sequence length
ISL / OSLBenchmark metrics
Input length is how much the model reads; output length is how much it writes. “8K/1K” means a long prompt followed by a shorter answer.
Interactivity
Benchmark metrics
Interactivity is how quickly one person sees new words appear after the model starts answering.
Iso-interactivity
Benchmark metrics
Iso-interactivity compares systems while users see words appear at the same speed. This provides an apples-to-apples view of the hardware behind the experience.
K
L
M
Memory bandwidth
Hardware
Memory bandwidth is the width of the pipe feeding data to the GPU’s compute units. A wider pipe keeps them from sitting idle.
Mixture of experts
MoEModel architecture
A mixture-of-experts model is like a large team of specialists: it calls only the few experts best suited to each token instead of using the whole team every time.
Multi-head latent attention
MLAModel architecture
MLA compresses the model’s notes about earlier tokens so long conversations use less memory and are cheaper to continue.
Multi-token prediction
MTPServing
MTP lets the model guess several upcoming tokens at once and then verify them, reducing the number of slow one-token-at-a-time steps.
MXFP4
Numerical precision
MXFP4 is a 4-bit format that gives small groups of numbers their own scale, helping very compact values keep enough useful range.
N
NVFP4
Numerical precision
NVFP4 is NVIDIA’s Blackwell-optimized version of 4-bit model math, designed to move less data and use the GPU’s fastest low-precision hardware.
NVIDIA Dynamo
Software
NVIDIA Dynamo coordinates many GPU workers. It routes requests, moves model memory, and assigns prompt reading and answer generation to the right pools.
NVLink
Hardware
NVLink is NVIDIA’s high-speed highway between GPUs, allowing them to cooperate much faster than over ordinary server networking.
P
Pareto frontier
Benchmark metrics
The Pareto frontier is the line of best available tradeoffs. Each point remains viable because improving one dimension would require giving up ground on another.
Performance per dollar
Benchmark metrics
Performance per dollar measures how much useful AI output the system produces for each dollar spent running it.
Prefill
Serving
Prefill is the model reading and understanding your prompt before it begins writing the answer.
Prefix caching
Serving
Prefix caching remembers the work for a repeated beginning, such as the same system prompt, so the model can skip that work next time.
Q
R
S
Scale-up vs. scale-out networking
Parallelism
Scale-up is the ultra-fast network inside one tightly connected GPU system. Scale-out is the broader network connecting separate servers or racks.
SGLang
Software
SGLang is open-source software for serving language models quickly, with scheduling and optimization features for complex AI workloads.
Sparse attention
Model architecture
Sparse attention lets the model look back at only the most useful parts of a long context instead of rereading every earlier token.
Speculative decoding
Serving
Speculative decoding lets a cheaper helper draft several tokens ahead, then asks the full model to approve them together instead of generating each one separately.
T
Tensor parallelism
TPParallelism
Tensor parallelism splits one large calculation across several GPUs so they solve it together.
TensorRT-LLM
Software
TensorRT-LLM is NVIDIA’s optimized software stack for getting high inference performance from NVIDIA GPUs.
Throughput
Benchmark metrics
Throughput is how much total work the system gets done each second across everyone using it.
Time per output token
TPOTBenchmark metrics
TPOT is the gap between each new piece of a streamed answer. Smaller gaps make the response feel faster and smoother.
Time to first token
TTFTBenchmark metrics
TTFT is the “thinking…” pause between sending your prompt and seeing the first piece of the answer.
Tokens per megawatt
Benchmark metrics
Tokens per megawatt asks how much AI output a data center can produce from a fixed amount of available power.
Total cost of ownership
TCOBenchmark metrics
TCO covers the hardware purchase plus the cost of powering, cooling, networking, and operating it over time.
V
W
Reading the benchmark
The full curve tells the story.
LLM serving balances per-user speed against aggregate throughput. InferenceX uses full Pareto curves and matched-interactivity comparisons to show that tradeoff across operating points. One maximum-throughput point cannot rank the complete system.
Grounded in measurements
Definitions connected to real recipes.
Every term page links to InferenceX articles where the concept changes a measured result, including MTP acceptance behavior, NVL72 wide-EP scaling, and software-only speedups on unchanged GPUs.