Autoscaling is a key mechanism in model-as-a-service systems, where fast scale-up is essential because the scale-up time directly determines how long a model service remains overloaded, which in turn governs serving quality. The state-of-the-art approach, model sleeping, adopted by mainstream serving engines including vLLM and SGLang, achieves near-zero-cost scale-up by pausing pre-spawned engines on the GPU. However, sleeping is not a free lunch: each sleeping model must keep its GPU context resident, and this cost grows linearly with the number of models, degrading serving performance. Because providers must support many models, they face a dilemma between fast scale-up for all models and high service performance. In this paper, we show that a single server can keep many models asleep without paying this GPU context tax. The key observation is that the contexts of sleeping models are largely duplicated: the driver (CUDA) context can be shared across models, and their GPU kernel binaries overlap heavily due to common operators and libraries. PhOSv1 deduplicates this context by transparently delegating each engine's GPU context allocation to a central daemon through API remoting; therefore, a single server can keep far more models asleep than current engines allow. Our evaluation shows that PhOSv1 matches the scale-up time of vanilla vLLM sleep mode while substantially reducing the GPU memory footprint, improving end-to-end multi-model serving performance.
Kai Ma, Tianle Sun, Shun Zhou, Boyao Yang, Ningyu He, Haoyu Wang
Many decentralized exchanges use automated market makers (AMMs) to trade assets against liquidity pools. Modern AMMs allow third-party contracts, called Hooks, to customize this process. However, Hooks can impose additional deductions that fee breakdowns based on standard pool parameters do not itemize. We present, to the best of our knowledge, the first large-scale empirical study of the production Hook ecosystem, focusing on these undisclosed settlement charges. Our study covers 7,873 Hook deployments, 50,011 pools, and 296M pool events on Uniswap v4 and PancakeSwap Infinity across Ethereum and BNB Smart Chain (BSC) through August 1, 2026. We develop a bytecode analysis that reconstructs how Hooks change traders' payments and receipts, separating charges from exchanged assets and standard fees. We then reconstruct historical settlements to measure charging frequency and economic burden. We find that direct settlement adjustment is the dominant Hook capability, supported by 71.37% of registered Hooks. Charging capability is widespread and often exercised: 24.30% of Hooks can impose undisclosed deductions, and these deductions occur in 59.23% of accounted swaps involving such Hooks. These charges generate millions of dollars in revenue, with $3.97M recorded across Hooks with available token prices. These findings reveal a gap between standard fee displays and actual trading costs, motivating explicit disclosure of Hook deductions alongside standard fees.