\input{configpres}

\title{Realtime Linux}
\maketitle

\subtitle{Realtime}

\begin{frame}
\frametitle{What is realtime?}
\begin{itemize}
\item correctness also means executing at the correct time
\item failing to meet timing restrictions leads to an error
\end{itemize}
\end{frame}

\begin{frame}
\frametitle{Realtime ''concrete''}
\begin{overprint}
\onslide<1>
\begin{alertblock}{Remember...}
Failing to meet timing restrictions leads to an error!
\end{alertblock}
\onslide<2|handout:0>
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/nuclear.png}
\end{figure}
\end{overprint}
\end{frame}

\begin{frame}
\frametitle{Fields of Application}
\begin{itemize}
\item Controlling / Automation
\item Multimedia
\item Air and Space Technology
\item Financial Services
\item ...
\end{itemize}
\end{frame}

\begin{frame}
\frametitle{Requirements}
\begin{itemize}
\item Deterministic Time Behavior
\item Interruptible
\item Priority Inheritance / Priority Ceiling
\end{itemize}
\end{frame}

\subsubsection{Priority Inversion}
\begin{frame}
\frametitle{Priority Inversion}
\begin{figure}[h]
\centering
\includegraphics[width=0.8\textwidth]{images/pinv.png}
\end{figure}
\end{frame}

\begin{frame}
\frametitle{Priority Inheritance}
\begin{figure}[h]
\centering
\includegraphics[width=0.8\textwidth]{images/pinh.png}
\end{figure}
\end{frame}

\subsubsection{Linux and Realtime}
\begin{frame}
\frametitle{Linux and Realtime}
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/gpos_vs_rt.png}
\end{figure}
\end{frame}

\begin{frame}
\frametitle{Approaches}
\begin{itemize}
\item Dual Kernel
\item In Kernel / Single Kernel
\end{itemize}
\end{frame}

\begin{frame}
\frametitle{Dual Kernel}
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/dual_kernel.png}
\end{figure}
\end{frame}

\begin{frame}
\frametitle{Single Kernel}
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/single_kernel.png}
\end{figure}
\end{frame}

\begin{frame}
\frametitle{RTAI}
\begin{itemize}
\item Prof. Paolo Mantegazza, University of Mailand
\item Dual kernel approach
\item Realtime in kernelspace
\item Realtime tasks in userspace possible with limitations
\item Main design goal: smallest possible latency times
\item Supported platforms: x86, x86\_64, several ARM platforms
\end{itemize}
\end{frame}

\begin{frame}
\frametitle{RTAI}
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/rtai.png}
\end{figure}
\end{frame}

\begin{frame}
\frametitle{Xenomai}
\begin{itemize}
\item Founded in 2001
\item Realtime in userpace
\item Skins emulate API's for varios RTOS systems
\item Dual kernel approach
\item Supported platforms: x86, x86\_64, PowerPC, ARM, ia64
\end{itemize}
\end{frame}

\begin{frame}
\frametitle{Xenomai}
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/xenomai.png}
\end{figure}
\end{frame}

\begin{frame}
\frametitle{Xenomai / IPIPE}
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/ipipe.png}
\end{figure}
\end{frame}

\begin{frame}
\frametitle{Marry in haste, repent at leisure...}
\begin{overprint}
\onslide<1|handout:0>
\begin{figure}[h]
\centering
\includegraphics[width=0.8\textwidth]{images/mar01.png}
\end{figure}
\onslide<2>
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/mar02.png}
\end{figure}
\onslide<3|handout:0>
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/mar03.png}
\end{figure}
\end{overprint}
\end{frame}

\begin{frame}
\frametitle{Preempt RT}
\begin{itemize}
\item Thomas Gleixner, Ingo Molnar
\item In Kernel Approach
\item Large development community
\item Many features already integrated in ''Mainline'' Linux
\item POSIX Realtime
\item Highly accepted, agreement in 2006 for complete Linux integration
\end{itemize}
\end{frame}

\begin{frame}
\frametitle{Preempt RT and Mainline}
\textit{''Controlling a laser with Linux is crazy, but everyone in this room is
crazy in his own way. So if you want to use Linux to control an industrial
welding laser, I have no problem with your using Preempt RT''} - Linus Torvalds
auf dem Kernel Summit 2006
\end{frame}

\begin{frame}
\frametitle{How does Preempt RT make Linux realtime capable?}
\begin{overprint}
\onslide<1|handout:0>
\begin{alertblock}{Remember...}
Interruptibility is a main requirement of a realtime system.
\end{alertblock}
\onslide<2>
\begin{itemize}
\item Locking primitives: Spinlocks are replaced with RT mutexes that can sleep. Raw spinlocks are introduced to provide the classic spinlock functionality.
\item Interrupt handlers run by default each as its own kernel thread.
\end{itemize}
\end{overprint}
\end{frame}

\begin{frame}
\frametitle{Preempt RT}
\begin{figure}[h]
\centering
\includegraphics[height=0.5\textwidth]{images/preempt_rt.png}
\end{figure}
\end{frame}

\input{tailpres}
