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RL models can be inefficient during inference. The GPU often sits idle while the CPU calculates rewards, then suddenly gets hit with a massive "burst" of activity. This unpredictable demand makes serving these models costly and complex, requiring conservative GPU allocation.

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The prevalence of guides on fixing TensorFlow input pipelines reveals a common but overlooked problem: slow data loading starves the GPU, wasting expensive compute. This shows performance optimization extends beyond model architecture and into the efficiency of data preprocessing and feeding stages.

Unlike simple classification (one pass), generative AI performs recursive inference. Each new token (word, pixel) requires a full pass through the model, turning a single prompt into a series of demanding computations. This makes inference a major, ongoing driver of GPU demand, rivaling training.

The GPU architecture is economically optimized for slow AI inference, offering a very low cost per token. However, this efficiency plummets when speed is required, as the cost and power per token increase exponentially, creating a market for alternative architectures in high-speed applications.

While GPUs train models, CPUs are essential for two key workloads: running reinforcement learning environments and executing the code generated by AI. This has created a massive, often overlooked demand spike, making CPUs a critical, sold-out component in the AI infrastructure stack and a hidden bottleneck.

A critical, under-discussed constraint on Chinese AI progress is the compute bottleneck caused by inference. Their massive user base consumes available GPU capacity serving requests, leaving little compute for the R&D and training needed to innovate and improve their models.

AI workloads, particularly for research and evals, don't follow predictable "follow-the-sun" patterns. They are extremely spiky, demanding massive compute resources instantly (e.g., 100,000 CPUs) and then dropping to zero. This forces providers like Daytona to maintain low mean utilization (15%) to handle unpredictable peaks.

Cursor and Fireworks intentionally use an asynchronous RL setup where the model used for generating experiences can be slightly behind the model being trained. This "staleness" is an accepted trade-off that keeps expensive GPUs constantly working, compensating for minor algorithmic inefficiencies with higher overall throughput.

The report of XAI's low GPU utilization reveals a critical, non-obvious bottleneck in AI: it's not just about acquiring compute, but using it efficiently. This 'FLOPS utilization' problem, caused by architectural and load-balancing issues, means billions in hardware sits underused, creating an opportunity for companies that can optimize the compute stack.

A major paradox exists in AI development: companies are desperate for scarce GPUs, yet often fail to use them efficiently. Even well-funded labs like XAI report model flops utilization as low as 11%, far below the 40% practical target, due to inconsistent workloads and data transfer bottlenecks.

Unlike traditional computing where inputs were standardized, LLMs handle requests of varying lengths and produce outputs of non-deterministic duration. This unpredictability creates massive scheduling and memory management challenges on GPUs that were not designed for such chaotic, real-time workloads.

Reinforcement Learning Models Are 'Bursty,' Creating GPU Idleness and Sudden Compute Spikes | RiffOn