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Advanced high-speed network cards have made packet processing in host operating systems a major performance bottleneck. The kernel network stack gives rise to various sources of overheads that limit the throughput and lengthen the per-packet processing latency. The problem is further exacerbated for short-lived, latency-sensitive network flows such as control packets, online gaming, database requests, etc. — in a highly utilized system, especially in virtualized (containerized) cloud environments, short flows can experience excessively long in-kernel queuing delays. As a consequence, recent research works propose to bypass the kernel network stack to enable lightweight, custom userspace network stacks for improved performance, but at a heavy cost of compatibility and security. In this paper, we take a different approach: We first analyze various sources of inefficiencies in the kernel network stack and propose ways to mitigate them without compromising systems compatibility, security, or flexibility. Further, we propose PRISM, a novel mechanism in the kernel network stack to differentiate incoming packets based on their performance requirements and streamline the processing stages of multi-stage packet processing pipelines (e.g., in container overlay networks). Our evaluation demonstrates that PRISM can significantly improve the latency of high-priority flows in container overly networks in the presence of heavy low-priority background traffic.
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Userspace Networking in gem5
Full-system simulation of computer systems is critical for capturing the complex interplay between various hard-ware and software components in future systems. Modeling the network subsystem is indispensable for the fidelity of full-system simulations due to the increasing importance of scale-out systems. Over the last decade, the network software stack has undergone major changes, with userspace networking stacks and data-plane networks rapidly replacing the conventional kernel network stack. Nevertheless, the current state-of-the-art architectural simulator, gem5, still employs kernel networking, which precludes realistic network application scenarios. In this work, we first demonstrate the limitations of gem5's current network stack in achieving high network bandwidth. Then, we enable a userspace networking stack on gem5. We extend gem5's NIC hardware model and device driver to sup-port userspace device drivers running the DPDK framework. Additionally, we implement a network load generator hardware model in gem5 to generate various traffic patterns and per-form per-packet timestamp and latency measurements without introducing packet loss. We develop a suite of six network-intensive benchmarks for stress testing the host network stack. These applications, based on DPDK, can run on both gem5 and real systems. Our experimental results show that enabling userspace networking improves gem5's network bandwidth by 6.3× compared with the current Linux kernel software stack. We characterize the performance of DPDK benchmarks running on both a real system and gem5, and evaluate the sensitivity of the applications to various system and microarchitecture parameters. This work marks the first step in refactoring the networking subsystem in gem5.
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- PAR ID:
- 10535819
- Publisher / Repository:
- IEEE
- Date Published:
- ISSN:
- 2766-0486
- ISBN:
- 979-8-3503-7638-8
- Page Range / eLocation ID:
- 179 to 191
- Format(s):
- Medium: X
- Location:
- Indianapolis, IN, USA
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/ISPASS61541.2024.00026
