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Disk vertical bar Crypt vertical bar Net: rethinking the stack for high-performance video streaming

Marinos, I; Watson, RNM; Handley, M; Stewart, RR; (2017) Disk vertical bar Crypt vertical bar Net: rethinking the stack for high-performance video streaming. In: SIGCOMM '17 Proceedings of the Conference of the ACM Special Interest Group on Data Communication. (pp. pp. 211-224). ACM: New York, NY, USA. Green open access

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Abstract

Conventional operating systems used for video streaming employ an in-memory disk buffer cache to mask the high latency and low throughput of disks. However, data from Netflix servers show that this cache has a low hit rate, so does little to improve throughput. Latency is not the problem it once was either, due to PCIe-attached flash storage. With memory bandwidth increasingly becoming a bottleneck for video servers, especially when end-to-end encryption is considered, we revisit the interaction between storage and networking for video streaming servers in pursuit of higher performance. We show how to build high-performance userspace network services that saturate existing hardware while serving data directly from disks, with no need for a traditional disk buffer cache. Employing netmap, and developing a new diskmap service, which provides safe high-performance userspace direct I/O access to NVMe devices, we amortize system overheads by utilizing efficient batching of outstanding I/O requests, process-to-completion, and zerocopy operation. We demonstrate how a buffer-cache-free design is not only practical, but required in order to achieve efficient use of memory bandwidth on contemporary microarchitectures. Minimizing latency between DMA and CPU access by integrating storage and TCP control loops allows many operations to access only the last-level cache rather than bottle-necking on memory bandwidth. We illustrate the power of this design by building Atlas, a video streaming web server that outperforms state-of-the-art configurations, and achieves ~72Gbps of plaintext or encrypted network traffic using a fraction of the available CPU cores on commodity hardware.

Type: Proceedings paper
Title: Disk vertical bar Crypt vertical bar Net: rethinking the stack for high-performance video streaming
Event: Conference of the ACM-Special-Interest-Group-on-Data-Communication (SIGCOMM), 21 - 25 August 2017, Los Angeles, CA, USA
Location: Los Angeles, CA
Dates: 21 August 2017 - 25 August 2017
Open access status: An open access version is available from UCL Discovery
DOI: 10.1145/3098822.3098844
Publisher version: https://doi.org/10.1145/3098822.3098844
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Network stacks; Storage stacks; Network Performance
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Computer Science
URI: http://discovery.ucl.ac.uk/id/eprint/10062261
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