A new category of "NeoCloud" or "AI-native cloud" is rising, focusing specifically on AI training and inference. Unlike general-purpose clouds like AWS, these platforms are GPU-first, catering to massive AI workloads and addressing the GPU scarcity and different workload patterns found in hyperscalers.

Modal Labs provides an infrastructure layer that sits above hyperscalers and specialized AI clouds. Its value is not owning hardware but abstracting the complexity of managing raw GPU capacity. By offering a superior developer experience and a flexible, usage-based model, it solves the variable demand problem inherent in AI applications.

Instead of building data centers, Modal runs a software layer across 17 cloud and bare-metal providers. This allows them to focus on software innovation and build a reliability layer that can leverage less-reliable but available 'neo-cloud' capacity.

Simply "scaling up" (adding more GPUs to one model instance) hits a performance ceiling due to hardware and algorithmic limits. True large-scale inference requires "scaling out" (duplicating instances), creating a new systems problem of managing and optimizing across a distributed fleet.

Model architecture decisions directly impact inference performance. AI company Zyphra pre-selects target hardware and then chooses model parameters—such as a hidden dimension with many powers of two—to align with how GPUs split up workloads, maximizing efficiency from day one.

The value of serverless multi-node training isn't competing with massive pre-training clusters. Its sweet spot is smaller-scale post-training and fine-tuning, where researchers need elasticity to run many small, bursty experiments without managing a dedicated cluster.

While many focus on compute metrics like FLOPS, the primary bottleneck for large AI models is memory bandwidth—the speed of loading weights into the GPU. This single metric is a better indicator of real-world performance from one GPU generation to the next than raw compute power.

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.

The key advantage of larger GPU clusters is their ability to use the memory bandwidth of all GPUs in parallel to load model weights. This massive aggregate bandwidth dramatically reduces memory fetch times, which is a primary latency bottleneck, especially for very large, sparse models.