QLinux: Quality of Service (QoS) enhanced Linux

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(Last updated: Apr. 12, 2000)

QLinux is a Linux kernel that can provide Quality of Service (QoS) guarantees for "soft real-time" Linux performance in application such as multimedia, data collection, etc. The current version of QLinux, based on the Linux 2.2.x kernel, combines some of the latest innovations in operating systems research and includes the following features:

Hierarchical Start Time Fair Queuing (H-SFQ) CPU scheduler
Hierarchical Start Time Fair Queuing (H-SFQ) network packet scheduler
Lazy receiver processing (LRP) network subsystem
Cello disk scheduling algorithm [not stable yet]

The H-SFQ CPU scheduler enables hierarchical scheduling of applications by fairly allocating cpu bandwidth to individual applications and application classes. The H-SFQ packet scheduler provides rate guarantees and fair allocation of bandwidth to packets from individual flows as well as flow aggregates (classes). Lazy receiver processing enables accurate charging of TCP/UDP protocol processing overhead (including interrupt processing) to the appropriate process. The Cello disk scheduler supports multiple application classes such as interactive best-effort, throughput-intensive best effort and soft real-time and fairly allocates disk bandwidth to these classes.

When enabled, these features replace the standard features/schedulers available in Linux. The current release provides the flexibility of allowing any combination of these features to be compiled as needed.

The latest version is 2.2.0 (based on the 2.2.0 kernel) A version based on the Linux 2.2.9 kernel will be available soon. The QLinux website includes the entire source code, a patch for the 2.2.0 kernel, release notes, sample applications, man pages, and other QLinux related info.

The QLinux developers can be reached at qlinux@cs.umass.edu.

QLinux announcements are available by subscribing to the qlinux-announce mailing list. To subscribe, please send a mail to majordomo@cs.umass.edu with the text "subscribe qlinux-announce".

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