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Have you ever realized how productive the Documentation team is? Not long ago I posted blogs about the new documentation for SUSE OpenStack Cloud 6 and SUSE Linux Enterprise Server for SAP Applications. But this is not the only product documentation the team has published during the past weeks.

Many of today’s largest high-profile organizations rely on time-dependent applications and processes, which must execute accurately and predictably all the time, every time. This is why organizations are turning to SUSE Linux Enterprise Real Time Extension. This is an extension to SUSE Linux Enterprise Server that shares the same kernel tree and ensures performance in time-critical environments.

In high performance computing (HPC), for example, systems are pushing for faster response times—especially in critical-needs environments—and more and more end users are demanding real-time responses for their compute needs. Real-time Linux was driven first by military and scientific needs; today, however, customers in enterprises such as banking and Wall Street trading, manufacturing, government agencies and others as well demand real-time support.

SUSE Linux Enterprise Real Time is an industry-standard, fully supported, real-time Linux operating system that runs on a variety of industry-standard platforms and gives you the performance you need, from small systems up to many CPU multi-core systems.

Its enriched version of the SUSE Linux Enterprise kernel has been specifically engineered to reduce the latency and increase the predictability and reliability of time-sensitive, mission-critical applications. It provides guaranteed performance in time-critical environments for hardware-in-the-loop simulations, data acquisition or process control.

Key features include kernel preemption with adaptive locks, CPU shielding and resource assignment, per device interrupt threads and priority inheritance as well as high-resolution timers. It also includes support for OpenFabrics Enterprise Distribution, a switched fabric commodity interconnect requiring little processing overhead that helps you achieve sustainable, real-time performance on Linux, command line monitoring, performance and development tools and, of course, documentation, which I would like to highlight here.

A big THANK YOU goes to my colleague Thomas Schraitle for his efforts to put together – based on the input of our subject matter experts Matt Fleming, Jeffrey Cheung and Libor Pecháček – the following real-time documentation:

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First, there is the Quickstart Guide. Of course, SUSE Linux Enterprise Real Time Extension always needs a SUSE Linux Enterprise Server 12 SP1 base system, as it cannot be installed in stand-alone mode. If you need to install a completely new server with SUSE Linux Enterprise Server SP1, you can choose to install SUSE Linux Enterprise Real Time Extension 12 SP1 as a registered add-on product during the fresh installation. If your SUSE Linux Enterprise Server base system is already installed, you can start the add-on product installation from YaST. In seven short chapters, the Quickstart Guide explains everything you need to know to install your real-time environment and configure it properly. And chapter 8 provides you with additional information about SUSE Linux Enterprise Real Time Extension.

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Next, you will find a document called SUSE Linux Enterprise Real Time Hardware Testing for version 12 SP1. SUSE Linux Enterprise Real Time Extension needs real-time capable hardware. This guide describes the tools that can be used to determine if specific hardware has the needed real-time capabilities. Specifically, you´ll find a description of the cyclictest program, which is part of the real-time kernel testsuite. What´s more, you get an explanation of the hardware latency detector, which is a special kernel module used to detect large system latencies caused by the behavior of underlying hardware or firmware, independent of Linux itself. And, of course, you will also learn more about the ways to analyze the results of these two tools. As mentioned, both the cyclictest and the hardware latency detector are parts of the SUSE Linux Enterprise Real Time Extension product.

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Also important is the short Virtualization Guide. SUSE Linux Enterprise Real Time Extension supports open source KVM and Xen virtualization, as well as VMware and Microsoft Hyper-V. Real-time and standard virtual machines are supported on the same physical server. This capability delivers higher density of real-time systems in virtual machines on a single server. Just be aware that system configurations that share CPUs between both RT and KVM workloads are not supported; proper isolation of workloads is imperative for achieving RT deadline constraints.

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Finally, we have provided updates to the paper How to Shield Your Linux Resources – SUSE Linux Enterprise Real Time Extension 12 SP1, originally written by Alex Tsariounov, a true expert for real-time environments. In CPU shielding real-time tasks can run on one CPU or core (of a multiprocessor system or multi-core CPU) while non-real-time tasks run on another. A shielded CPU is a CPU dedicated to the activities associated with high-priority real-time tasks. Marking a CPU as shielded allows CPU resources to be reserved for high-priority tasks. The execution environment of a shielded CPU provides the predictability required for supporting real-time applications. In other words, a shielded CPU makes it possible to guarantee rapid response to external interrupts and to provide a more deterministic environment for executing real-time tasks.

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As always, we would be delighted  to get your feedback for our new documentation. Comments and ideas for improvements are highly appreciated. Just reach out to doc-team@suse.de with your comments and proposals.

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