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Identifier

000394829

Title

Low-latency implementation of network sockets over remote DMA

Alternative Title

Υλοποίηση δικτυακών sockets χαμηλής καθυστέρησης μέσω απομακρυσμένου DMA

Author

Πουλιός, Δημήτριος Μ.

Thesis advisor

Κατεβαίνης, Εμμανουήλ

Reviewer

Μπίλας, Άγγελος
Πρατικάκης, Πολύβιος

Abstract

In recent years, changes in the server market have brought power and space efficient server designs, like the Microserver. Such designs utilize large numbers of lightweight compute nodes bundled together to serve scale-out data center workloads. Unfortunately, scalability can often be limited by the quality of internal communication among running nodes, where low throughput and, even more critically, high latency can lead to poor performance. In this work, we explore the efficiency of a Remote Direct Memory Access (RDMA) capable internal network in a Microserver environment. Applications commonly use the standard Socket API for interprocess communication across networks. Therefore, to take advantage of the aforementioned internal network without modifying existing applications, socket-related system calls have to be intercepted. We implement system call interception in user space, using a modified Standard C Library, in order to bypass the kernel TCP/IP stack. A kernel driver has also been developed to securely perform data transfers via RDMA operations, which require physical addresses. Remote completion notifications of RDMA operations are triggered by a custom hardware Mailbox Mechanism, which also handles communication among nodes, necessary to initiate and close local connections. By combining these user and kernel space elements, we direct local TCP traffic through our internal network. Evaluation results show a 3x to 5x improvement to the latency, using our system compared to a typical ethernet configuration.

Language

English, Greek

Subject

Kernel bypass

Low latency

RDMA

Sockets

System-call interception

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