RealTime

Revision 27 as of 2007-03-28 03:57:08

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Please check the status of this specification in Launchpad before editing it. If it is Approved, contact the Assignee or another knowledgeable person before making changes.

Summary

This specification details the plan to add hard real time support in Ubuntu.

Rationale

In some contexts (i.e. industrial automation, robotics and telco) the low-latency support is insufficient. In order to push Ubuntu in these contexts it is necessary to add support for high resolution timers and full preemption in the Linux kernel. These features have been implemented by Thomas Gleixner and Ingo Molnar (http://people.redhat.com/mingo/realtime-preempt/).

We also want a valid FLOSS alternative to SLERT (http://www.novell.com/products/realtime/).

Use cases

Alex is developing an application software (SCADA type) for a customer and he would be very happy to use Linux and Ubuntu for the deployment.

Real time audio support in a radio station studio (http://postscriptumradio.org), which needs RT preemption to satisfy real time features of jack audio connection kit by Paul Davis.

Scope

This specification covers the linux kernel in Ubuntu.

Implementation

We hope to add a linux-image-realtime package in the universe repository (the same place as the linux-image-lowlatency package). Talk to /MOTU/Teams/Audio seems they ar eduplicating the load with a low latency audio kernel.

Beta available

Add, as root, to your /etc/apt/sources.list (remember to do a backup of this file) the following line:

deb http://www.texware.it/ubuntu feisty/

Then execute:

wget -q http://www.texware.it/ubuntu/feisty/BBA3222D.gpg -O- | sudo apt-key add -BR sudo apt-get updateBR sudo apt-get install linux-realtime

Packages available:

linux-realtimeBR linux-image-realtimeBR linux-image-2.6.20-12-realtime (2.6.20-rt8)BR cyclictest

Patch is available at:

http://www.texware.it/ubuntu/feisty/Ubuntu-2.6.20-8.14-realtime.diff BR http://www.texware.it/ubuntu/feisty/Ubuntu-2.6.20-9.16-realtime.diff BR http://www.texware.it/ubuntu/feisty/Ubuntu-2.6.20-10.17-realtime.diff BR http://www.texware.it/ubuntu/feisty/Ubuntu-2.6.20-11.18-realtime.diff BR http://www.texware.it/ubuntu/feisty/Ubuntu-2.6.20-12.19-realtime.diff BR

Todo

Debug versionBR Restricted modules package (when kernel in Feisty is freeze)BR Amd64 kernel version (any volunteer?)BR

BoF agenda and discussion

  • Any suggestion/feedbacks/requests? - AlessioIgorBogani

  • I can host the packages on my repo if bandwith is necessary [wiki:Ttoine ttoine]

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