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2021-11-29 - 16:40

Dates and Events:

OSADL Articles:

2021-09-06 12:00

"OSADL Track" at EWC 2022: Call for Papers

All about legal and technical issues and solutions when using Open Source software in industry

2021-02-09 12:00

Open Source OPC UA PubSub over TSN project phase #3 launched

Letter of Intent with call for participation is now available

2016-11-12 12:00

Raspberry Pi and real-time Linux

Let's have a look at the OSADL QA Farm data

2016-09-17 12:00

Preemption latency of real-time Linux systems

How to measure it – and how to fix it, if it's too high?

Details of the Real Time Linux Foundation Working Group Project

OSADL Project: Real Time Linux Workshops

Real Time Linux Foundation Workshops since 1999

Real Time Linux Workshops

1999 - 2000 - 2001 - 2002 - 2003 - 2004 - 2005 - 2006 - 2007 - 2008 - 2009 - 2010 - 2011 - 2012 - 2013 - 2014 - 2015

Twelfth Real-Time Linux Workshop on October 25 to 27, in Nairobi, Kenya

The basis for Real-Time Ethernet protocols in Linux

Thomas Gleixner and Sebastian Siewior, Linutronix GmbH, Germany

Even if the latest PREEMPT_RT patched Linux kernel is used, the network stack can inflict unbound latencies on real-time Ethernet protocols due to:

  • Socket buffer allocations
  • Traffic congestion with non real-time traffic

In a proof-of-concept implementation, the following mechanisms are used
to overcome the above limitations:

  • Generic preallocated socket buffer pools
  • Protocol-specific traffic policing and traffic shaping

This approach is minimally invasive to the network stack and has zero impact when the real-time protocol related functions are not enabled:

  • Network card drivers require no or minimal changes to support preallocated buffer pools
  • Traffic control is modular and only loaded and enabled when required
  • No restriction on network tools and network functionality

The paper does not cover the complex user space part of real-time Ethernet protocols.