- PTQPost-Training Quantization17%
- Quantizing an already-trained model using a calibration set to observe activation distributions and derive per-tensor scale factors, with no retraining. Fast, but its accuracy degrades more than QAT's at very low precision.
- QATQuantization-Aware Training17%
- Inserting quantize/dequantize (QDQ) nodes so a model learns to tolerate reduced precision during training. Requires retraining, but usually wins on accuracy over PTQ, especially at INT4 or FP4.
- GPTQ17%
- A one-shot, post-training, weight-only quantization method using approximate second-order (Hessian) information. It can quantize a 175B-parameter model to 3–4 bits per weight in a few GPU hours with negligible accuracy loss — a distinct method from both PTQ and QAT, not a variant of either.
- KV cacheKey-Value cache17%
- Stored per-token attention keys and values from tokens already processed, kept so autoregressive decoding does not recompute attention over the whole prefix at every step. It is the primary latency lever for decoder inference — it spends memory to buy speed, not the other way around.
- Tensor parallelism14%
- Splitting a single layer's weight tensors across GPUs (intra-layer), reducing per-GPU model-state and activation memory. The standing distractor pair with pipeline parallelism, which splits across layers instead.
- Pipeline parallelism14%
- Splitting consecutive layers or segments of a model across GPUs (inter-layer), with interleaved or virtual-pipeline scheduling used to shrink the idle "bubble." Splits across layers, where tensor parallelism splits within one.
- ZeRO / FSDP14%
- A distributed optimizer that shards optimizer states — and optionally parameters and gradients — across data-parallel GPUs, typically via reduce-scatter then all-gather. A memory-sharding technique layered on data parallelism, not a separate parallelism axis.
- LoRALow-Rank Adaptation13%
- A parameter-efficient fine-tuning method that freezes the pretrained weights and injects small trainable low-rank matrices into each transformer layer. Versus full fine-tuning of GPT-3 175B, it cuts trainable parameters by roughly 10,000x and memory by about 3x, and — because the adapters can be merged into the base weights — adds no inference latency.
- DPODirect Preference Optimization13%
- Fine-tuning directly on preference pairs with a supervised-style loss, with no separate reward model and no RL sampling loop — the language model implicitly plays the reward model. If an answer describes DPO as training a reward model then running PPO, it is describing classic RLHF instead.
- GRPOGroup Relative Policy Optimization13%
- A critic-free variant of PPO, introduced with DeepSeekMath, that drops the separate value network and estimates advantages from group-relative normalized scores across multiple sampled outputs per prompt — lower memory cost than PPO, with a reasoning-focused training signal.
- Perplexity7%
- The exponentiated average negative log-likelihood of a sequence under a model — equivalently, the exponentiation of cross-entropy. Lower is better, it applies only to autoregressive/causal LMs, and scores are only comparable across models sharing the same tokenizer.
- Faithfulness7%
- A Ragas RAG-evaluation metric measuring whether a generated answer is grounded in its retrieved context. Distinct from answer relevancy (does the answer address the question) and from context precision/recall, which assess retrieval quality rather than the final answer text.
- NeMo Curator9%
- NVIDIA's tool for large-scale LLM data curation — cleaning, deduplicating, and organizing training data at scale, paired in practice with RAPIDS cuDF for GPU-accelerated dataframe operations.
- Dynamo-Triton9%
- NVIDIA's production inference server, formerly Triton Inference Server. Runs models across frameworks with dynamic batching (stateless models), sequence batching (stateful models), and concurrent execution via instance groups. Serves what it is given; it does not optimize the model itself.
- NIMNVIDIA Inference Microservices9%
- Portable, performance-optimized, containerized inference microservices with curated weights and an OpenAI-compatible API. Modern NIM LLM 2.0 follows a "one container, one backend" design with vLLM as the engine — a higher-level, prepackaged microservice, distinct from the general-purpose Dynamo-Triton server underneath the category.
- Drift7%
- A gradual decline in output quality as real-world inputs shift away from the training or validation distribution over time — data drift (the input distribution changes) or concept drift (the input-output relationship changes). A model that passed evaluation at launch is not protected from it.
- Guardrails5%
- Programmable safety layers, such as NeMo Guardrails, that constrain what a model can discuss or produce across topical, safety/content, and security rails, governing both inputs and outputs. They steer and restrict behavior at runtime; they do not debias or retrain the underlying model.