PromptWise: Online Learning for Cost-Aware Prompt Assignment in Generative Models (2505.18901v1)

Abstract: The rapid advancement of generative AI models has provided users with numerous options to address their prompts. When selecting a generative AI model for a given prompt, users should consider not only the performance of the chosen model but also its associated service cost. The principle guiding such consideration is to select the least expensive model among the available satisfactory options. However, existing model-selection approaches typically prioritize performance, overlooking pricing differences between models. In this paper, we introduce PromptWise, an online learning framework designed to assign a sequence of prompts to a group of LLMs in a cost-effective manner. PromptWise strategically queries cheaper models first, progressing to more expensive options only if the lower-cost models fail to adequately address a given prompt. Through numerical experiments, we demonstrate PromptWise's effectiveness across various tasks, including puzzles of varying complexity and code generation/translation tasks. The results highlight that PromptWise consistently outperforms cost-unaware baseline methods, emphasizing that directly assigning prompts to the most expensive models can lead to higher costs and potentially lower average performance.

Analysis of "PromptWise: Online Learning for Cost-Aware Prompt Assignment in Generative Models"

The selection of generative models, particularly when addressing specific prompts, necessitates a careful consideration of both performance metrics and associated service costs. The paper "PromptWise: Online Learning for Cost-Aware Prompt Assignment in Generative Models," authored by Xiaoyan Hu et al., introduces PromptWise—an online learning framework developed to optimize prompt assignments across a group of LLMs by balancing performance expectations with cost considerations.

Core Contributions and Framework

The authors begin by challenging the traditional model-selection approaches common in AI, which tend to prioritize performance without considering economic factors. The advancement of LLMs has diversified the market, resulting in significant price variance among models. PromptWise addresses this oversight by adopting a novel approach where the assignment strategy systematically queries less costly models initially, escalating to more expensive ones only when necessary. Such an approach aligns with rational decision-making strategies where economic efficiency does not compromise functional outcomes.

The framework is grounded in a budget-aware contextual bandit algorithm, leveraging the Upper Confidence Bound (UCB) principle to manage uncertainty in model performance predictions. The sum-min regret structure is novel in its ability to factor in both performance-derived regrets and cost accumulation, ensuring that only the best obtainable performance for each prompt impacts performance regret while all relevant modeling costs are considered cumulatively.

Experimental Validation

PromptWise was empirically validated using a series of tasks, including cognitive puzzles, code generation, and translation, with a diverse array of LLMs. The numerical experiments demonstrated that PromptWise consistently outperformed cost-unaware selection methods. Saliently, the method achieved better cost-performance trade-offs, maintaining or even enhancing prompt-handling effectiveness while significantly reducing expenses when juxtaposed with default strategies of assigning prompts to higher-cost models. This evidences a functional efficacy within practical settings, where budget constraints are common operational realities.

Key Results and Implications

The paper highlights the superior adaptive capacity of PromptWise compared to baseline models in simulated environments. By strategically balancing computational costs against prompt specification needs, PromptWise embodies an optimization policy that other model selectors can emulate. Moreover, the application of prompt-specific optimized assignments not only ensures economic justifiability but also maintains high-level cognitive task performance across varied complexity levels.

Practically, integrating cost-awareness into model selection algorithms could reduce operational expenses for businesses leveraging AI technologies. In theoretical realms, the methodologies utilized to inform PromptWise’s algorithm establish an analytical precedent for modeling cost considerations in machine learning frameworks, promoting greater efficiencies in computational resource allocations.

Prospective Developments

Given the current trajectory in generative AI, extending PromptWise's functionality to other areas such as text-to-video models and broader task domains seems a logical future direction. There is also potential integration with offline model selection strategies, creating hybrid models that further refine cost-performance ratios across diverse deployment environments.

Overall, "PromptWise: Online Learning for Cost-Aware Prompt Assignment in Generative Models” carves out a distinct niche in model selection literature by expressly incorporating cost-awareness, presenting a balanced, adaptable, and economically feasible solution to AI prompt assignment challenges. This methodological shift could well define new standards for model selection protocols by aligning operational efficiencies with cost pragmatism.