Lightweight manycore processors deliver high performance and scalability by bundling in a single chip hundreds of low-power cores, a distributed memory architecture and Networks-on-Chip (NoCs). Operating Systems (OSes) for these processors feature a distributed design, in which a communication layer enables kernels to exchange information and interoperate. Currently, this communication infrastructure is based on mailboxes, which enable fixed-size message exchanges with low latency. However, this solution is suboptimal because it can neither fully exploit the NoC nor efficiently handle the diversity of OS communication protocols. We propose an Inter-Kernel Communication (IKC) facility that exposes two kernel-level communication abstractions in addition to mailboxes: syncs, for enabling a process to signal and unlock another process remotely, and portals, for handling dense data transfers with high bandwidth. We implemented the proposed facility in Nanvix, the only open-source distributed OS that runs on a baremetal lightweight manycore, and we evaluated our solution on a 288-core processor (Kalray MPPA-256). Our results showed that our IKC facility achieves up to 16.87× and 1.68× better performance than a mailbox-only solution, in synchronization and dense data transfers, respectively.

轻量级多核处理器通过将数百个低功耗内核，分布式内存架构和片上网络（NoC）捆绑在一个芯片中，从而提供了高性能和可扩展性。这些处理器的操作系统（OS）具有分布式设计，其中的通信层使内核可以交换信息并进行互操作。当前，此通信基础结构基于邮箱，邮箱可以以低延迟进行固定大小的消息交换。但是，此解决方案不是最优的，因为它既不能充分利用NoC，也不能有效地处理OS通信协议的多样性。我们提出了一种内核间通信（IKC）工具，该工具除了邮箱外还公开了两个内核级通信抽象：syncs，用于使一个进程能够远程发出信号并解锁另一个进程，以及门户网站，用于处理具有高带宽的密集数据传输。我们在Nanvix中实施了拟议的设施，Nanvix是唯一在裸机轻量级manycore上运行的开源分布式OS，并且我们在288核处理器（Kalray MPPA-256）上评估了我们的解决方案。我们的结果表明，与仅使用邮箱的解决方案相比，我们的IKC设施在同步和密集数据传输方面分别实现了高达16.87倍和1.68倍的更好性能。