An Evaluation of One-Sided and Two-Sided Communication Paradigms on Relaxed-Ordering Interconnect
An Evaluation of One-Sided and Two-Sided Communication Paradigms on Relaxed-Ordering Interconnect
复制标题
松序互连上单侧和两侧通信范式的评估
DOI：
--
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
K. Yelick
中科院分区：
文献类型：
--
作者：
K. Ibrahim;Paul H. Hargrove;Costin Iancu;K. Yelick
Cray Gemini 互连硬件提供多种传输机制和无序消息传递，以提高通信吞吐量。在本文中，我们量化了单侧和双向通信范例在以下方面的性能：1）最佳可用硬件传输机制，2）消息排序约束，3）每个节点和每个核心的消息并发性。除了使用 Cray 本机通信 API 之外，我们还使用 UPC 和 MPI 微基准分别捕获单侧和双向语义。我们的结果表明，与严格排序相比，放宽消息传递顺序可以将性能提高高达 4.6 倍。当硬件允许时，高级单向编程模型已经可以利用消息重新排序。强制执行双边通信的排序语义会带来性能损失。此外，我们认为下一代编程模型需要在应用程序级别公开无序交付。语言规范中的任何排序限制都会降低小消息的通信性能，并增加峰值吞吐量所需的活动核心数量。
The Cray Gemini interconnect hardware provides multiple transfer mechanisms and out-of-order message delivery to improve communication throughput. In this paper we quantify the performance of one-sided and two-sided communication paradigms with respect to: 1) the optimal available hardware transfer mechanism, 2) message ordering constraints, 3) per node and per core message concurrency. In addition to using Cray native communication APIs, we use UPC and MPI micro-benchmarks to capture one- and two-sided semantics respectively. Our results indicate that relaxing the message delivery order can improve performance up to 4.6x when compared with strict ordering. When hardware allows it, high-level one-sided programming models can already take advantage of message reordering. Enforcing the ordering semantics of two-sided communication comes with a performance penalty. Furthermore, we argue that exposing out-of-order delivery at the application level is required for the next-generation programming models. Any ordering constraints in the language specifications reduce communication performance for small messages and increase the number of active cores required for peak throughput.