Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

what is RT_PREEMPT? how is it different from preempt rt ?does these mean same real time patch to linux? [closed]

I presently working on hardrealtime linux. when i search regarding documentation of topic RT_PREEMPT . different sites turn up with different names like preempt-rt,rt-preempt.

can someone say me the exact link or any resources which could help me look on RT_PREEMPT?

like image 373
IamSeekingAns Avatar asked Oct 11 '14 06:10

IamSeekingAns


People also ask

What does preempt RT do?

PREEMPT_RT makes interrupts run as threads, so you have the ability to modify the priorities of interrupts as well, and have user space tasks run at even a higher priority than interrupts. Having interrupts run as threads lets you prioritize the interrupt handlers even when the hardware does not support it.

What is a Linux real-time kernel?

What is the real-time kernel? A real-time kernel is not necessarily superior or better than a standard kernel. Instead, it meets different business or system requirements. It is an optimized kernel designed to maintain low latency, consistent response time, and determinism.


1 Answers

You are looking for the RT_Preempt patch, which is documented here. The patch makes the kernel fully preemptable, and also includes some RT schedulers. It includes a how-to for installing it. If you are familiar with building kernels it should be pretty easy.

I documented my installation on my Ubuntu machine here.

It is kinda difficult to find up-to-date information on the patch in part because much of it has become mainline in the last few years (having multiple names doesn't help either). For example, the 3.14 kernel has configuration options for a "low-latency" install.

Steven Rostedt gave a good overview talk in 2013 at the Embedded Linux Conference, available at linuxgizmos.com and youtube. Slides here (pdf). Around minute 17 he really starts to get into the differences:

  • Interrupts are handled with threads (thus scheduled)
  • Spin locks replaced with mutexes
  • Priority inheritance is extended to the kernel
like image 101
superdesk Avatar answered Sep 28 '22 12:09

superdesk