Motivated by the increasing importance of general-purpose Graphic Processing Units (GPGPU) programming, exemplified by NVIDIA’s CUDA framework, as well as the difficulty, especially for novice programmers, of reasoning about performance in GPGPU kernels, we introduce a novel quantitative program logic for CUDA kernels. The logic allows programmers to reason about both functional correctness and resource usage of CUDA kernels, paying particular attention to a set of common but CUDA-specific performance bottlenecks: warp divergences, uncoalesced memory accesses, and bank conflicts. The logic is proved sound with respect to a novel operational cost semantics for CUDA kernels. The semantics, logic, and soundness proofs are formalized in Coq. An inference algorithm based on LP solving automatically synthesizes symbolic resource bounds by generating derivations in the logic. This algorithm is the basis of RaCUDA, an end-to-end resource-analysis tool for kernels, which has been implemented using an existing resource-analysis tool for imperative programs. An experimental evaluation on a suite of benchmarks shows that the analysis is effective in aiding the detection of performance bugs in CUDA kernels.
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Reclaiming Logic Modeling for Evaluation: A Theory of Action Framework
Logic modeling, the process that explicates how programs are constructed and theorized to bring about change, is considered to be standard evaluation practice. However, logic modeling is often experienced as a transactional, jargon-laden, discrete task undertaken to produce a document to comply with the expectations of an external entity, the consequences of which have minimal or even negative influence on the quality of program evaluation. This article presents the Logic Modeling Theory of Action Framework (LMTAF) which elucidates needs, resources, and central activities of logic modeling, and describes its potential evaluation-related benefits. The LMTAF situates evaluators as the primary intended users of logic modeling, and logic modeling as a fundamental element of each stage of a program evaluation life cycle. We aim to reassert the value of logic modeling for evaluation and provide evaluation practitioners a useful touchstone for reflective practice and future action.
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- PAR ID:
- 10535656
- Publisher / Repository:
- American Journal of Evaluation
- Date Published:
- Journal Name:
- American Journal of Evaluation
- ISSN:
- 1098-2140
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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