A New Lens on Multi-GPU Comms: API-Level Memory Models for Portable Optimization

A paper submitted to arXiv on 12 October 2026 proposes API-level memory models for device-side multi-GPU communication APIs such as rocSHMEM, MSCCL++ and NCCL/RCCL GIN, which currently lack a rigorous memory model. The authors define one such model for device-side communication, implemented in AMD's recently open-sourced rocSHMEM library, and show that formal relaxations enabling cache bypassing for network data improve a collective communication workload by up to 2.48x, a fused compute+communication workload by up to 1.77x, and a state-of-the-art expert-parallel communication workload by up to 1.18x.

Computer Science Distributed, Parallel, and Cluster Computing Submitted on 12 Oct 2026 Title:A New Lens on Multi-GPU Communication: API-Level Memory Models for Portable Optimization View PDF https://arxiv.org/pdf/2610.16190 Abstract:As network communication increasingly becomes a performance bottleneck for ML and HPC workloads, it is more important than ever to optimize multi-GPU data transfers. Recently, low-level device APIs have emerged that allow programmers to perform fine-grain optimizations via one-sided put/get operations triggered directly from the device. However, the communication libraries providing these device APIs e.g., rocSHMEM, MSCCL++, and NCCL/RCCL GIN currently lack a rigorous memory model defining how their primitives interact with the underlying memory systems. Without this, emerging HPC and ML workloads aggressively optimizing network communication via device APIs can be brittle, error-prone, and face compatibility and inter-operability challenges. This paper proposes the use of API-level memory models for these emerging device communication APIs. An API-level memory model defines the memory semantics of communication API calls in a way that abstracts lower-level details from the API user and simplifies development. This work defines one such model for device-side communication implemented in AMD's recently open sourced rocSHMEM library and demonstrates how formal relaxations to such a model can enable low-level LLM performance optimizations while retaining a well-defined standardized interface. Specifically, we describe how updating the SHMEM API implemented by rocSHMEM can properly support cache bypassing for network data, improving performance of a collective communication workload by up to 2.48x, a fused compute+communication workload by up to 1.77x, and a state-of-the-art expert-parallel communication workload by up to 1.18x. Additional Features References & Citations Loading... Bibliographic and Citation Tools Bibliographic Explorer What is the Explorer? https://info.arxiv.org/labs/showcase.html arxiv-bibliographic-explorer Connected Papers What is Connected Papers? https://www.connectedpapers.com/about Litmaps What is Litmaps? https://www.litmaps.co/ scite Smart Citations What are Smart Citations? https://www.scite.ai/ Code, Data and Media Associated with this Article alphaXiv What is alphaXiv? https://alphaxiv.org/ CatalyzeX Code Finder for Papers What is CatalyzeX? https://www.catalyzex.com DagsHub What is DagsHub? https://dagshub.com/ Gotit.pub What is GotitPub? http://gotit.pub/faq Hugging Face What is Huggingface? https://huggingface.co/huggingface ScienceCast What is ScienceCast? https://sciencecast.org/welcome Demos Recommenders and Search Tools Influence Flower What are Influence Flowers? https://influencemap.cmlab.dev/ CORE Recommender What is CORE? https://core.ac.uk/services/recommender arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs https://info.arxiv.org/labs/index.html .