This document provides an overview of systemd and how it differs from traditional init systems. It discusses systemd units and how to manage services using systemctl. It covers customizing units using drop-ins, managing resources with cgroups, converting init scripts, and using the systemd journal. The presentation aims to demystify systemd and provide administrators with practical guidance on using its main features.
Systemd is a system and service manager that replaces SysVinit and aims to be a unified system for Linux systems. It provides enhanced service management through "unit" configuration files and capabilities like socket activation. Systemd allows for process isolation and containerization. While it has advantages like improved integration and security, some criticize it as being too complex, monopolistic, and forcing adoption through essential components.
Systemd is a new init system for Linux that is replacing sysvinit. It aims to address issues with sysvinit like synchronous startup and slow shell scripts. While systemd provides benefits like asynchronous startup of services and use of configuration files, it is also controversial due to concerns about feature creep and being Linux-specific. Many major Linux distributions have adopted systemd as the default init system.
Systemd is a system and session manager for Linux that is compatible with SysV and LSB init scripts. It provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services, offers on-demand starting of daemons, and keeps track of processes using Linux cgroups. Systemd implements an elaborate transactional dependency-based service control logic and can work as a drop-in replacement for sysvinit.
RHEL 7 will use systemd as its init system, replacing upstart. Systemd is more than just an init system replacement - it is a system and service manager that provides features like dependency tracking, process supervision, on-demand starting of services, and lightweight boot process. It introduces new unit file types to define system components and their relationships. Customizing services can be done by editing unit files and using systemctl commands.
Systemd is a system and service manager that replaces sysvinit. It manages services, devices, mounts and other system components. It relies on control groups (cgroups) to isolate and manage processes and resources for each service. Services are configured through declarative unit files instead of shell scripts. Systemd provides features like socket activation, timers, and integrates with journald for logging.
CLUG 2010 09 - systemd - the new init systemPaulWay
The document discusses systemd, a new init system for Linux that aims to make booting faster by starting processes in parallel and starting fewer processes. It does this by setting up sockets in parallel and starting daemons on demand when sockets are opened. This approach is inspired by xinetd and is also used by other operating systems like Mac OS X. Systemd provides features like managing processes, units to configure services and sockets, and is coming to major Linux distributions. Daemons will need to adapt by avoiding things like forking and writing PID files.
Systemd is a system and service manager that provides modular, asynchronous, and concurrent services. It allows administrators to create snapshots of unit configurations. Some key capabilities it provides include listing and controlling systemd units and services. A service file template is also provided that defines properties like the service description, execution commands, and installation targets. Systemd-nspawn can be used to create lightweight containers with their own isolated namespaces.
Systemd is a system and service manager that replaces SysVinit and aims to be a unified system for Linux systems. It provides enhanced service management through "unit" configuration files and capabilities like socket activation. Systemd allows for process isolation and containerization. While it has advantages like improved integration and security, some criticize it as being too complex, monopolistic, and forcing adoption through essential components.
Systemd is a new init system for Linux that is replacing sysvinit. It aims to address issues with sysvinit like synchronous startup and slow shell scripts. While systemd provides benefits like asynchronous startup of services and use of configuration files, it is also controversial due to concerns about feature creep and being Linux-specific. Many major Linux distributions have adopted systemd as the default init system.
Systemd is a system and session manager for Linux that is compatible with SysV and LSB init scripts. It provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services, offers on-demand starting of daemons, and keeps track of processes using Linux cgroups. Systemd implements an elaborate transactional dependency-based service control logic and can work as a drop-in replacement for sysvinit.
RHEL 7 will use systemd as its init system, replacing upstart. Systemd is more than just an init system replacement - it is a system and service manager that provides features like dependency tracking, process supervision, on-demand starting of services, and lightweight boot process. It introduces new unit file types to define system components and their relationships. Customizing services can be done by editing unit files and using systemctl commands.
Systemd is a system and service manager that replaces sysvinit. It manages services, devices, mounts and other system components. It relies on control groups (cgroups) to isolate and manage processes and resources for each service. Services are configured through declarative unit files instead of shell scripts. Systemd provides features like socket activation, timers, and integrates with journald for logging.
CLUG 2010 09 - systemd - the new init systemPaulWay
The document discusses systemd, a new init system for Linux that aims to make booting faster by starting processes in parallel and starting fewer processes. It does this by setting up sockets in parallel and starting daemons on demand when sockets are opened. This approach is inspired by xinetd and is also used by other operating systems like Mac OS X. Systemd provides features like managing processes, units to configure services and sockets, and is coming to major Linux distributions. Daemons will need to adapt by avoiding things like forking and writing PID files.
Systemd is a system and service manager that provides modular, asynchronous, and concurrent services. It allows administrators to create snapshots of unit configurations. Some key capabilities it provides include listing and controlling systemd units and services. A service file template is also provided that defines properties like the service description, execution commands, and installation targets. Systemd-nspawn can be used to create lightweight containers with their own isolated namespaces.
Systemd is an init system that replaces traditional init daemons. It allows for parallel startup of services through dependency-based activation of units which encapsulate system objects like services, devices, and mounts. Systemd also provides on-demand activation of services through sockets, buses, devices, and file paths. It aims to be backwards compatible with System V while offering improvements like parallel startup and centralized logging.
This document provides an overview of using systemd to manage services effectively. It discusses defining service behavior and types, handling timeouts and failures, tightening security, and automating monitoring and management. The key steps outlined are to define expected behavior, plan for the unexpected, tighten security early, and automate monitoring. Various systemd directives and options are explained for tasks like controlling resources, dependencies, reloading, and failure handling.
Systemd: the modern Linux init system you will learn to loveAlison Chaiken
The talk combines a design overview of systemd with some tutorial incofrmation about how to configure it. Systemd's features and pitfalls are illustrated by short demos and real-life examples. Files used in the demos are listed under "Presentations" at http://she-devel.com/
Video of the live presentation will appear here:
http://www.meetup.com/Silicon-Valley-Linux-Technology/events/208133972/
RHEL7 uses systemd to manage services and runlevels, with targets replacing traditional runlevels. It uses XFS as the default filesystem which supports larger maximum file and filesystem sizes. Network bonding is called a team driver in RHEL7. Chrony replaces ntp for network time synchronization and Mariadb replaces Mysql as the default database.
Systemd provides a more modular approach to system initialization and service management compared to SysVinit and Upstart. With systemd, various system initialization tasks and services are defined as independent "units" that have dependencies and startup ordering defined through configuration files. At boot, systemd analyzes the dependencies between units and starts them in parallel where possible to reduce startup time. It provides standardized methods for process supervision and resource management of services.
While probably the most prominent, Docker is not the only tool for building and managing containers. Originally meant to be a "chroot on steroids" to help debug systemd, systemd-nspawn provides a fairly uncomplicated approach to work with containers. Being part of systemd, it is available on most recent distributions out-of-the-box and requires no additional dependencies.
This deck will introduce a few concepts involved in containers and will guide you through the steps of building a container from scratch. The payload will be a simple service, which will be automatically activated by systemd when the first request arrives.
- Systemd is now the most widely used Linux init system, replacing sysVinit. It has a superior design with tight integration with the Linux kernel.
- Systemd aims to extract duplicate functionality from individual daemons and replace init scripts with declarative configuration files. It provides a single daemon, systemd, to manage all system services.
- While systemd exemplifies needed modernization of Linux, its rapid development and deprecation of features could cause problems during the transition by distributions.
The latest releases of today’s popular Linux distributions include all the tools needed to do interesting things with Linux containers.
For the Makefile MicroVPS project, I set out to build a minimal virtual private server-like environment in a Linux container from scratch.
These are my requirements for the MicroVPS:
Minimal init sequence
Most of what happens in a rc.sysinit file is not needed (or wanted) in a container. However, to work like a virtual private server, the MicroVPS will need some kind of init system. The absolute minimum would be enough to start the network and at least one service.
Native network namespace
The MicroVPS will have a dedicated network namespace. It should be easy to configure.
Native package management
The package set installed in the container image will be managed using native tools like deb or rpm.
Automated build
An automated repeatable build process is a must.
Fast iteration cycle
The building and testing cycle must be fast enough not to drive me insane.
Easy management
It should be easy to distribute, monitor, and run a MicroVPS container.
In this tutorial, I will show how to use the tools included with Linux to build a virtual private server in a Linux container from scratch, using GNU Make to automate the build process.
This document provides an overview of the differences between SystemV and systemd for initializing Linux systems. It begins with some background on systemd and its objectives to improve on outdated SystemV startup processes. The document then covers key aspects of systemd such as its functions, strategy of on-demand starting of services, and implementation details. It also discusses the benefits of systemd and compares some pros and cons between the two approaches.
The document discusses several key topics about the FreeBSD operating system including:
- How to use the virtual consoles of FreeBSD and log into the system.
- An overview of UNIX file permissions and flags in FreeBSD.
- The default directory structure and disk organization of FreeBSD.
- How to mount and unmount file systems using the fstab file and mount/unmount commands.
- Concepts of processes, daemons, signals and killing processes.
- What shells are and how to change your default login shell.
1. The document discusses debugging FreeBSD kernels through various tools and techniques such as kgdb(1), ddb(4), ktrace(1), and kdump(1).
2. Common issues like kernel crashes and hangs can be debugged using tools that examine CPU registers, step through code, and analyze kernel traces.
3. Effective debugging requires understanding kernel data structures and configuration options for enabling debugging features.
The document provides an overview of the FreeBSD operating system boot process and file hierarchy. It discusses how the boot0 and boot1 programs initialize the system and load the boot2 program. Boot2 then loads the loader, which uses a bootinfo structure to pass information to the kernel and load it into memory to start the operating system. The document also describes the standard FreeBSD file hierarchy and the purpose of the main directories like /bin, /sbin, /etc, /usr, /var, and /boot.
This document discusses hardware settings and configuration on Linux systems. It covers determining hardware settings using HAL, D-Bus and Udev. It explains how HAL uses sysfs to store hardware information, how udev rules map hardware to device files in /dev, and how modules can be loaded, removed and listed. Kernel configuration files in /proc are also described. The document provides contact information for questions.
The document summarizes key aspects of the C compilation model and process concepts in operating systems. It discusses that the C compilation model involves preprocessing, compilation, assembly, and linking. It also explains that a process is a program in execution with a unique process ID, that processes are created through forking, and that signals allow processes to communicate termination status. Process attributes like user IDs, group IDs, and process groups are also covered.
The document discusses Linux services and run levels. It explains that Linux uses scripts in /etc/rc.d and /etc/init.d directories to start and stop services during boot up and shutdown. These scripts are executed in different run levels which determine the system configuration and available processes. The document also provides details on the structure and contents of different run level directories, a skeleton for service scripts, and how to use update-rc.d to automatically start scripts on boot.
This document discusses various security concepts in FreeBSD including file system protections like flags, access control lists, kernel security levels, jails, and techniques to harden the operating system like write xor execute (W^X) and cryptography. It provides details on file flags like immutable, append-only, and nodump and how they can be used to secure files. It also explains how to create and manage jails to isolate processes and provides an overview of tools to help administer jails.
This document provides a cheatsheet comparing commands for managing services and system states between SysV init and systemd. It lists the equivalent systemd commands for common SysV init commands like service, chkconfig, and runlevels. It also covers commands for viewing and filtering journal logs, changing targets/runlevels, and rebooting/powering off the system.
This document discusses the transition from SysV init to systemd as the init system in Linux. It provides an overview of SysV init and some of its limitations. It then introduces systemd as an alternative and describes some of its key features and commands, including systemctl for controlling services, journalctl for viewing logs, and utilities for analyzing boot performance. The document argues that systemd offers improvements in areas like parallelization of boot processes and service supervision.
This document provides instructions for setting up FreeBSD jails with a shared read-only template and individual read-write partitions for each jail. It describes creating a master template with installed binaries and ports, then creating directories for each jail mounted via nullfs. Individual jail configurations are added to rc.conf and the jails are started and can be managed via jexec. Upgrades involve building a new template and restarting the jails.
System Device Tree and Lopper: Concrete Examples - ELC NA 2022Stefano Stabellini
System Device Tree is an extension to Device Tree to describe all the hardware on an SoC, including heterogeneous CPU clusters and secure resources not typically visible to an Operating System like Linux. This full view allows the System Device Tree to be the "One true source" of the entire hardware description and helps to prevent the common (and hard-to-debug) problem of conflicting resources and system consistency. Lopper is an Open Source framework to parse and manipulate System Device Tree. With Lopper, it is possible to generate multiple traditional Device Trees from a single larger System Device Tree. This presentation will provide an overview of System Device Tree and will discuss the latest updates of the specification and tooling. The talk will illustrate multiple use-cases for System Device Tree with concrete examples, such as Linux running on the more powerful CPU cluster and Zephyr running on a smaller Cortex-R cluster. It will also show how to use Lopper to generate multiple traditional Device Trees targeting different OSes, not just Linux but also Zephyr/other RTOSes. Finally, an end-to-end demo based on Yocto to build a complete heterogeneous system with multiple OSes and RTOSes running on different clusters on a single reference board will be shown.
This document discusses tools for managing large scale computing environments: Cobbler, Puppet, and Func. Cobbler is a provisioning system that automates OS installation and configuration. Puppet is a configuration management tool that defines system configurations and ensures consistency. Func provides a Python API to manage systems, allowing them to be treated as Python objects. It includes modules to control services, run commands, and integrate with monitoring tools like Nagios. These tools help reduce complexity and enable consistent configuration of large numbers of systems.
Systemd is an init system that replaces traditional init daemons. It allows for parallel startup of services through dependency-based activation of units which encapsulate system objects like services, devices, and mounts. Systemd also provides on-demand activation of services through sockets, buses, devices, and file paths. It aims to be backwards compatible with System V while offering improvements like parallel startup and centralized logging.
This document provides an overview of using systemd to manage services effectively. It discusses defining service behavior and types, handling timeouts and failures, tightening security, and automating monitoring and management. The key steps outlined are to define expected behavior, plan for the unexpected, tighten security early, and automate monitoring. Various systemd directives and options are explained for tasks like controlling resources, dependencies, reloading, and failure handling.
Systemd: the modern Linux init system you will learn to loveAlison Chaiken
The talk combines a design overview of systemd with some tutorial incofrmation about how to configure it. Systemd's features and pitfalls are illustrated by short demos and real-life examples. Files used in the demos are listed under "Presentations" at http://she-devel.com/
Video of the live presentation will appear here:
http://www.meetup.com/Silicon-Valley-Linux-Technology/events/208133972/
RHEL7 uses systemd to manage services and runlevels, with targets replacing traditional runlevels. It uses XFS as the default filesystem which supports larger maximum file and filesystem sizes. Network bonding is called a team driver in RHEL7. Chrony replaces ntp for network time synchronization and Mariadb replaces Mysql as the default database.
Systemd provides a more modular approach to system initialization and service management compared to SysVinit and Upstart. With systemd, various system initialization tasks and services are defined as independent "units" that have dependencies and startup ordering defined through configuration files. At boot, systemd analyzes the dependencies between units and starts them in parallel where possible to reduce startup time. It provides standardized methods for process supervision and resource management of services.
While probably the most prominent, Docker is not the only tool for building and managing containers. Originally meant to be a "chroot on steroids" to help debug systemd, systemd-nspawn provides a fairly uncomplicated approach to work with containers. Being part of systemd, it is available on most recent distributions out-of-the-box and requires no additional dependencies.
This deck will introduce a few concepts involved in containers and will guide you through the steps of building a container from scratch. The payload will be a simple service, which will be automatically activated by systemd when the first request arrives.
- Systemd is now the most widely used Linux init system, replacing sysVinit. It has a superior design with tight integration with the Linux kernel.
- Systemd aims to extract duplicate functionality from individual daemons and replace init scripts with declarative configuration files. It provides a single daemon, systemd, to manage all system services.
- While systemd exemplifies needed modernization of Linux, its rapid development and deprecation of features could cause problems during the transition by distributions.
The latest releases of today’s popular Linux distributions include all the tools needed to do interesting things with Linux containers.
For the Makefile MicroVPS project, I set out to build a minimal virtual private server-like environment in a Linux container from scratch.
These are my requirements for the MicroVPS:
Minimal init sequence
Most of what happens in a rc.sysinit file is not needed (or wanted) in a container. However, to work like a virtual private server, the MicroVPS will need some kind of init system. The absolute minimum would be enough to start the network and at least one service.
Native network namespace
The MicroVPS will have a dedicated network namespace. It should be easy to configure.
Native package management
The package set installed in the container image will be managed using native tools like deb or rpm.
Automated build
An automated repeatable build process is a must.
Fast iteration cycle
The building and testing cycle must be fast enough not to drive me insane.
Easy management
It should be easy to distribute, monitor, and run a MicroVPS container.
In this tutorial, I will show how to use the tools included with Linux to build a virtual private server in a Linux container from scratch, using GNU Make to automate the build process.
This document provides an overview of the differences between SystemV and systemd for initializing Linux systems. It begins with some background on systemd and its objectives to improve on outdated SystemV startup processes. The document then covers key aspects of systemd such as its functions, strategy of on-demand starting of services, and implementation details. It also discusses the benefits of systemd and compares some pros and cons between the two approaches.
The document discusses several key topics about the FreeBSD operating system including:
- How to use the virtual consoles of FreeBSD and log into the system.
- An overview of UNIX file permissions and flags in FreeBSD.
- The default directory structure and disk organization of FreeBSD.
- How to mount and unmount file systems using the fstab file and mount/unmount commands.
- Concepts of processes, daemons, signals and killing processes.
- What shells are and how to change your default login shell.
1. The document discusses debugging FreeBSD kernels through various tools and techniques such as kgdb(1), ddb(4), ktrace(1), and kdump(1).
2. Common issues like kernel crashes and hangs can be debugged using tools that examine CPU registers, step through code, and analyze kernel traces.
3. Effective debugging requires understanding kernel data structures and configuration options for enabling debugging features.
The document provides an overview of the FreeBSD operating system boot process and file hierarchy. It discusses how the boot0 and boot1 programs initialize the system and load the boot2 program. Boot2 then loads the loader, which uses a bootinfo structure to pass information to the kernel and load it into memory to start the operating system. The document also describes the standard FreeBSD file hierarchy and the purpose of the main directories like /bin, /sbin, /etc, /usr, /var, and /boot.
This document discusses hardware settings and configuration on Linux systems. It covers determining hardware settings using HAL, D-Bus and Udev. It explains how HAL uses sysfs to store hardware information, how udev rules map hardware to device files in /dev, and how modules can be loaded, removed and listed. Kernel configuration files in /proc are also described. The document provides contact information for questions.
The document summarizes key aspects of the C compilation model and process concepts in operating systems. It discusses that the C compilation model involves preprocessing, compilation, assembly, and linking. It also explains that a process is a program in execution with a unique process ID, that processes are created through forking, and that signals allow processes to communicate termination status. Process attributes like user IDs, group IDs, and process groups are also covered.
The document discusses Linux services and run levels. It explains that Linux uses scripts in /etc/rc.d and /etc/init.d directories to start and stop services during boot up and shutdown. These scripts are executed in different run levels which determine the system configuration and available processes. The document also provides details on the structure and contents of different run level directories, a skeleton for service scripts, and how to use update-rc.d to automatically start scripts on boot.
This document discusses various security concepts in FreeBSD including file system protections like flags, access control lists, kernel security levels, jails, and techniques to harden the operating system like write xor execute (W^X) and cryptography. It provides details on file flags like immutable, append-only, and nodump and how they can be used to secure files. It also explains how to create and manage jails to isolate processes and provides an overview of tools to help administer jails.
This document provides a cheatsheet comparing commands for managing services and system states between SysV init and systemd. It lists the equivalent systemd commands for common SysV init commands like service, chkconfig, and runlevels. It also covers commands for viewing and filtering journal logs, changing targets/runlevels, and rebooting/powering off the system.
This document discusses the transition from SysV init to systemd as the init system in Linux. It provides an overview of SysV init and some of its limitations. It then introduces systemd as an alternative and describes some of its key features and commands, including systemctl for controlling services, journalctl for viewing logs, and utilities for analyzing boot performance. The document argues that systemd offers improvements in areas like parallelization of boot processes and service supervision.
This document provides instructions for setting up FreeBSD jails with a shared read-only template and individual read-write partitions for each jail. It describes creating a master template with installed binaries and ports, then creating directories for each jail mounted via nullfs. Individual jail configurations are added to rc.conf and the jails are started and can be managed via jexec. Upgrades involve building a new template and restarting the jails.
System Device Tree and Lopper: Concrete Examples - ELC NA 2022Stefano Stabellini
System Device Tree is an extension to Device Tree to describe all the hardware on an SoC, including heterogeneous CPU clusters and secure resources not typically visible to an Operating System like Linux. This full view allows the System Device Tree to be the "One true source" of the entire hardware description and helps to prevent the common (and hard-to-debug) problem of conflicting resources and system consistency. Lopper is an Open Source framework to parse and manipulate System Device Tree. With Lopper, it is possible to generate multiple traditional Device Trees from a single larger System Device Tree. This presentation will provide an overview of System Device Tree and will discuss the latest updates of the specification and tooling. The talk will illustrate multiple use-cases for System Device Tree with concrete examples, such as Linux running on the more powerful CPU cluster and Zephyr running on a smaller Cortex-R cluster. It will also show how to use Lopper to generate multiple traditional Device Trees targeting different OSes, not just Linux but also Zephyr/other RTOSes. Finally, an end-to-end demo based on Yocto to build a complete heterogeneous system with multiple OSes and RTOSes running on different clusters on a single reference board will be shown.
This document discusses tools for managing large scale computing environments: Cobbler, Puppet, and Func. Cobbler is a provisioning system that automates OS installation and configuration. Puppet is a configuration management tool that defines system configurations and ensures consistency. Func provides a Python API to manage systems, allowing them to be treated as Python objects. It includes modules to control services, run commands, and integrate with monitoring tools like Nagios. These tools help reduce complexity and enable consistent configuration of large numbers of systems.
Cobbler, Func and Puppet: Tools for Large Scale EnvironmentsMichael Zhang
This document discusses tools for managing large scale computing environments: Cobbler, Puppet, and Func. Cobbler is a provisioning system that automates OS installation and configuration. Puppet is a configuration management tool that defines system configurations and ensures consistency. Func provides a Python API to manage systems, allowing them to be treated as Python objects. It includes modules to control services, run commands, and integrate with monitoring tools like Nagios. These tools help reduce complexity and enable consistent configuration of large numbers of systems.
Performance Analysis: new tools and concepts from the cloudBrendan Gregg
Talk delivered at SCaLE10x, Los Angeles 2012.
Cloud Computing introduces new challenges for performance
analysis, for both customers and operators of the cloud. Apart from
monitoring a scaling environment, issues within a system can be
complicated when tenants are competing for the same resources, and are
invisible to each other. Other factors include rapidly changing
production code and wildly unpredictable traffic surges. For
performance analysis in the Joyent public cloud, we use a variety of
tools including Dynamic Tracing, which allows us to create custom
tools and metrics and to explore new concepts. In this presentation
I'll discuss a collection of these tools and the metrics that they
measure. While these are DTrace-based, the focus of the talk is on
which metrics are proving useful for analyzing real cloud issues.
In this PowerPoint, learn how a security policy can be your first line of defense. Servers running AIX and other operating systems are frequent targets of cyberattacks, according to the Data Breach Investigations Report. From DoS attacks to malware, attackers have a variety of strategies at their disposal. Having a security policy in place makes it easier to ensure you have appropriate controls in place to protect mission-critical data.
This document discusses daemons in Linux operating systems. It defines daemons as background processes that perform tasks like responding to network requests and hardware activity. Some key daemons mentioned include init, cron, xinetd, inetd, sshd, and atd. Details are provided on what each daemon does and how they are configured through files like cron.allow, cron.deny, xinetd.conf, and sshd_config. The document also explains how services are enabled and disabled for different daemons using commands like insserv and insserv -r.
This document provides an overview of essential Linux commands and utilities for SQL Server DBAs. It covers topics such as Linux history, users and permissions, file editing and navigation commands like vi, process monitoring with ps and top, and system diagnostic utilities like sar, vmstat, and mpstat. The document aims to teach SQL Server DBAs basic Linux skills to manage their environment and troubleshoot issues.
This talk is a followup to Deploying systemd at scale that was presented at systemd.conf 2016, and covers the aftermath of the migration of our fleet to CentOS 7. Now that systemd is available everywhere, we found more and more services that started adopting it for their deployment, leveraging its features and occasionally exposing interesting behaviors. At the same time, we've been able to hone our process for integrating and rolling out new versions of systemd on the fleet, and started building tooling to manage and monitor it at scale.
The document provides instructions for setting up a TI-RTOS project for the CC1352R wireless microcontroller. It describes creating a CCS project targeting the CC1352R, configuring compiler and linker settings, generating a system configuration file, and adding TI-RTOS and driver library files. The goal is to build a basic "hello world" project to demonstrate real-time operating system functionality on the CC1352R wireless microcontroller.
Android boot time optimization involves measuring boot times, analyzing the results, and reducing times. Key areas of focus include the bootloader, kernel initialization, zygote class preloading, and system service startup. Hibernation technologies like QuickBoot and Fast-On can improve resume speeds by saving a system image to flash. The "R-Loader" concept aims to minimize hardware re-initialization on resume by directly loading a suspended kernel image.
A short overview of current technologies plucked from the Texas Linux Fest schedule for 2014. Includes overviews of systemd, popular configuration management tools, docker, distributed log collection, and openstack.
VMworld 2016: vSphere 6.x Host Resource Deep DiveVMworld
1. This document provides an overview and agenda for a presentation on vSphere 6.x host resource deep dive topics including compute, storage, and network.
2. It introduces the presenters, Niels Hagoort and Frank Denneman, and provides background on their expertise.
3. The document outlines the topics to be covered under each section, including NUMA, CPU cache, DIMM configuration, I/O queue placement, driver considerations, RSS and NetQueue scaling for networking.
Docker and friends at Linux Days 2014 in Praguetomasbart
Docker allows deploying applications easily across various environments by packaging them along with their dependencies into standardized units called containers. It provides isolation and security while allowing higher density and lower overhead than virtual machines. Core OS and Mesos both integrate with Docker to deploy containers on clusters of machines for scalability and high availability.
Quick-and-Easy Deployment of a Ceph Storage Cluster with SLESJan Kalcic
This document discusses quick deployment of a Ceph storage cluster using SUSE Linux Enterprise Server (SLES). It provides an overview of Ceph and its components, and steps for provisioning a Ceph cluster including bootstrapping an initial monitor, adding OSDs, and configuring a PXE boot server for automated installation. It also briefly introduces tools like SUSE Studio for appliance building and SUSE Manager for systems management that can aid in deploying and managing the Ceph cluster.
This document provides guidance on hardening a Linux server for security. It recommends following the CIS and NSA security benchmarks. It suggests choosing a server-oriented Linux distribution, keeping partitions and filesystems separate, encrypting partitions and the running server, securing the boot process, using iptables and TCP wrappers for firewalls, restricting root access and using sudo, enforcing password policies, removing unnecessary packages and services, securing remote administration like SSH, disabling unnecessary Linux modules, and implementing auditing and integrity checks.
This document provides an overview of kernel debugging on Solaris systems using the modular debugger Mdb and dynamic tracing framework DTrace. It discusses debugging live kernels with Mdb, analyzing system crash dumps with Mdb, and using DTrace to monitor the kernel at runtime by enabling probes published by different providers. The document outlines the key tools, techniques, and challenges involved in kernel debugging and crash analysis on Solaris.
Container technologies use namespaces and cgroups to provide isolation between processes and limit resource usage. Docker builds on these technologies using a client-server model and additional features like images, containers, and volumes to package and run applications reliably and at scale. Kubernetes builds on Docker to provide a platform for automating deployment, scaling, and operations of containerized applications across clusters of hosts. It uses labels and pods to group related containers together and services to provide discovery and load balancing for pods.
Here are some ways to optimize the code:
1. Use strtr() instead of preg_replace() since it avoids the overhead of regular expressions.
2. Define the replacement array outside the loop to avoid redefining it on each iteration.
3. Use direct string concatenation instead of sprintf() for better performance.
4. Avoid function calls inside the loop like sizeof(). Define the length before the loop for better performance.
5. Consider using string replacement/manipulation functions like str_replace() instead of redefining/reconcatenating strings on each loop iteration.
So in summary, the optimized code would be:
$rep = ['-' => '*', '.' => '*
The document discusses two new features in systemd for relating services and processes:
1) The ps command has been updated to show process control groups (cgroups), allowing users to see which service each process belongs to.
2) Each process spawned by a service is placed into a cgroup named after the service, ensuring processes are reliably labeled after the service that started them even if they change names or parentage. This allows services and their processes to be easily managed as a group.
How to debug systemd problems fedora projectSusant Sahani
This document provides instructions for debugging problems with the Systemd startup process in Fedora. It recommends checking the common bugs document first before filing a bug report. It then lists several useful Systemd commands for investigating services, targets, and the boot process. Finally it outlines some boot parameters that can help with debugging boot issues.
Systemd is a system and session manager for Linux that is compatible with SysV and LSB init scripts. It provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services, offers on-demand starting of daemons, and keeps track of processes using Linux cgroups. Systemd implements an elaborate transactional dependency-based service control logic and can work as a drop-in replacement for sysvinit.
- systemd tracks which processes belong to which services using control groups (cgroups)
- This allows administrators to see which processes are owned by each service using the ps command
- It also allows services and all their processes to be killed safely without risk of processes escaping the service's cgroup
- systemd tracks which processes belong to which services using control groups (cgroups)
- This allows administrators to see which processes are owned by each service using the ps command
- It also allows services and all their processes to be killed safely without risk of processes escaping the service's cgroup
Interface between kernel and user spaceSusant Sahani
The document discusses how traffic control (TC) works in the Linux kernel. It involves the following key steps:
1. A userspace TC application like tc creates a netlink socket and sends commands to modify queueing disciplines (qdiscs) and classes.
2. The kernel receives these commands via the rtnetlink socket and invokes functions like tc_modify_qdisc.
3. tc_modify_qdisc looks up interfaces, finds or creates the requested qdisc, and grafts it onto the interface using functions like qdisc_create, qdisc_graft, and dev_graft_qdisc.
4. Specific qdisc types like prio then further modify
- Binary trees are a data structure where each element has up to two children, allowing elements to be organized in a hierarchical tree-like structure. This allows items to be stored and searched more efficiently than linear data structures like linked lists.
- Searching and inserting items into a balanced binary tree takes O(log n) time, where n is the number of nodes, as each operation requires traversing a branching path proportional to the log of the number of elements. For large n, this provides much faster access than the O(n) time required to search a linked list.
- Binary trees can be traversed in different orders like in-order, pre-order and post-order to process or output the elements
This document provides background on the historical development of networking protocol stacks. It discusses how the original Multics architecture from the 1970s, which placed networking protocols in the kernel to minimize memory usage, became the standard model and was implemented in Unix. However, this kernel-based approach has several disadvantages for modern multicore systems, including reduced parallelism, lock contention, and extra data copies. The talk will argue for moving more protocol processing out of the kernel and into userspace to better leverage multiple cores.
2-3 trees and 2-4 trees are multiway search trees that maintain balance by ensuring each internal node has k items and k+1 children, allowing for efficient insertion and deletion. Red-black trees are a type of self-balancing binary search tree where each node is colored red or black, and properties of the coloring are used to perform rotations during insertion and deletion to maintain balance. Common operations like search, insertion and deletion on these balanced search tree structures take O(log n) time, improving on the O(n) time of an unbalanced binary search tree.
This document discusses kernel synchronization in Linux. It begins by outlining kernel control paths and when synchronization is necessary, such as to prevent race conditions when kernel control paths are interleaved. It then describes various synchronization primitives like spin locks, semaphores, and RCU. Examples are given of how these primitives can be used to synchronize access to kernel data structures. Interrupt-aware versions of synchronization primitives are also outlined. The document concludes with examples of how race conditions are prevented for specific data structures and operations in the kernel.
The document describes the process of preorder tree traversal using a stack. It involves pushing the root node to the stack, popping nodes from the stack and visiting them while also pushing their children, and repeating until the stack is empty. This traversal results in the root node being visited first, followed by left children, and then right children.
This document discusses using the BACnet protocol to remotely monitor and control devices over IP networks from handheld devices. BACnet allows communication with devices like HVAC systems, lighting systems, and industrial equipment. It describes two scenarios for accessing this functionality: through SMS/USSD commands, and through a smartphone app that uses XML requests. Both have advantages and disadvantages, such as the need to register services with multiple carriers for SMS access, while apps require development for different platforms and may use more data. The goal is to enable remote device access with minimal hardware investment using existing Internet and mobile infrastructure.
This document provides an overview of the Supersonic query engine API. Supersonic is a library for efficient columnar data processing that uses low-level optimizations for speed. The API focuses on Operations like Compute, Filter, and Sort that take a data source as input. Operations return a Cursor that can be used to pull results. Expressions are also supported and evaluate on input Views to produce output Views. The document discusses how to create and use Operations and Expressions, handle failures, and manage data and object lifetimes.
The document describes how to install and use the Verax SNMP Simulator to simulate network devices. It includes instructions to install the simulator, extract SNMP data from physical devices, add simulated devices to the simulator, start the simulator, and add simulated devices to the Verax NMS.
The document discusses kernel logging from the printk function in the kernel to log files in user space. It explores the printk API, how log messages move from the kernel ring buffer to user space via the syslog system call, and how rsyslog manages logs in user space.
Introduction to freebsd_6_kernel_hackingSusant Sahani
This document provides an introduction to customizing the FreeBSD 6 kernel through kernel module programming. It discusses topics such as the anatomy of a kernel module, including the use of DECLARE_MODULE and Makefiles. It also covers exporting configuration parameters through sysctl variables, and installing packet filters (PFIL) hooks. The document is intended to act as a primer for those new to FreeBSD kernel programming.
This document provides instructions and guidance for using LKCD and Kdump to capture Linux kernel crash dumps. It discusses the installation, configuration, and use of LKCD for local and network kernel crash dumping. It also covers the installation, configuration, and testing of Kdump for kernel crash dumping. Additional sections provide details on analyzing kernel crash dumps using the crash utility.
This document provides an overview of a training course on the Stream Control Transmission Protocol (SCTP). The objectives are to understand the technical details and operation of SCTP, know where to find relevant specification documents, understand the SCTP application programming interface, and be aware of ongoing extensions to SCTP. The course covers SCTP concepts like endpoints, associations, multi-homing, and the state machine. Reference materials and online resources are also listed.
3. systemd
•Controls “units” rather than just daemons
•Handles dependency between units.
•Tracks processes with service information
•Services are owned by a cgroup.
• Simple to configure “SLAs” based on CPU, Memory, and IO
•Properly kill daemons
•Minimal boot times
•Debuggability – no early boot messages are lost
•Easy to learn and backwards compatible
8. systemd Units – httpd.service
[Unit]
Description=The Apache HTTP Server
After=remote-fs.target nss-lookup.target
[Service]
Type=notify
EnvironmentFile=/etc/sysconfig/httpd
ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND
ExecReload=/usr/sbin/httpd $OPTIONS -k graceful
ExecStop=/usr/sbin/httpd $OPTIONS -k graceful-stop
KillSignal=SIGCONT
PrivateTmp=true
[Install]
WantedBy=multi-user.target *Comments were removed for readability
9. Managing Services – Unit files
Init
•Init scripts: /etc/init.d & called from /etc/rc*
systemd
•Maintainer files: /usr/lib/systemd/system
•Administrator files: /etc/systemd/system
•Non-persistent, runtime data: /run/systemd
Note: unit files under /etc will take precedence over /usr
19. Targets == Runlevels
•“Runlevels” are exposed as target units
•Target names are more relevant:
•multi-user.target vs. runlevel3
•graphical.target vs. runlevel5
•View the default target via: `systemctl get-default`
•Set the default target via: `systemctl set-default [target]`
•Change at run-time via: `systemctl isolate [target]`
Note: /etc/inittab is no longer used.
20. Troubleshooting
•Append systemd.unit=[target] to the kernel
• Rescue mode: single, s, S, or 1
• Emergency (similar to init=/bin/bash): -b or emergency
•Interactive boot append: systemd.confirm_spawn=1
•Enable debugging append:
• debug
• debug systemd.log_target=kmsg log_buf_len=1M
• debug systemd.log_target=console console=ttyS0
http://freedesktop.org/wiki/Software/systemd/Debugging/
21. Troubleshooting
•Early boot shell on tty9
• systemctl enable debug-shell.service
• Equivalent to: `ln -s /usr/lib/systemd/system/debug-shell.service
/etc/systemd/system/sysinit.target.wants/`
•systemctl list-jobs
•systemd-analyze
•Use 'blame', 'plot', or 'critical-chain' for more details
•rc.local is supported, but no longer runs last
• chmod +x /etc/rc.d/rc.local
23. What's available??
•List a unit's properties:
• systemctl show --all httpd
•Query a single property:
• systemctl show -p Restart httpd
• Restart=no
•Helpful man files: systemd.exec and systemd.service
•Restart, Nice, CPUAffinity, OOMScoreAdjust, LimitNOFILE, etc
Disclaimer: just because you can configure something doesn't mean you should!
24. Drop-ins
1) mkdir /etc/systemd/system/[name.type.d]/*.conf
2) vim /etc/systemd/system/httpd.service.d/50-httpd.conf
[Service] Remember the 'S' is capitalized
Restart=always
CPUAffinity=0 1 2 3
OOMScoreAdjust=-1000
3) systemctl daemon-reload
• Changes will be applied on top of maintainer unit files.
26. Drop-ins
•`systemd-delta` is your friend.
•Simple to use with configuration tools like Satellite, Puppet, etc.
•Simply delete the drop-in to revert to defaults.
•Don't forget `systemctl daemon-reload` when modifying units.
30. Contain Your Applications and Guarantee Service
•Configure how applications,
containers, and VMs will behave when
resources are under contention.
•Trivial to keep poorly written
applications from stomping on your
system.
My daughter was not harmed during the making of this presentation
31. Slices, Scopes, Services
•Slice – Unit type for creating the cgroup hierarchy for resource
management.
•Scope – Organizational unit that groups a services' worker
processes.
•Service – Process or group of processes controlled by systemd
32. Understanding the Hierarchy
-/
•systemd implements a standard, single-root hierarchy under
/sys/fs/cgroup/systemd
33. Understanding the Hierarchy
-/
user.slice system.slice machine.slice
•Each slice gets equal CPU time on the scheduler.
34. Understanding the Hierarchy
-/
user.slice system.slice machine.slice
CPUShares=1024 CPUShares=1024
CPUShares=1024
•Each slice gets equal CPU time on the scheduler.
35. Understanding the Hierarchy
-/
user.slice system.slice machine.slice
user-1000.slice
session-3.scope
sshd: user
bash
user-1001.slice
36. Understanding the Hierarchy
-/
user.slice system.slice machine.slice
user-1000.slice
session-3.scope
sshd: user
bash
user-1001.slice
CPUShares=1024
37. Understanding the Hierarchy
-/
user.slice system.slice machine.slice
user-1000.slice
session-3.scope
sshd: user
bash
tomcat.service
sshd.service
mariadb.service
httpd.service
user-1001.slice
38. Understanding the Hierarchy
-/
user.slice system.slice machine.slice
user-1000.slice
session-3.scope
sshd: user
bash
tomcat.service
sshd.service
mariadb.service
httpd.service
user-1001.slice
CPUShares=1024
42. Resource Management – Configuration
•Enable the desired controller(s) – CPU, Memory, BlockIO
•Configure cgroup attributes:
• systemctl set-property --runtime httpd.service CPUShares=2048
•Drop “--runtime” to persist:
• systemctl set-property httpd.service CPUShares=2048
•Or place in the unit file:
• [Service]
•CPUShares=2048
http://0pointer.de/blog/projects/resources.html
43. Resource Management - CPU
•CPUAccounting=1 to enable
•CPUShares – default is 1024.
•Increase to assign more CPU to a service
• e.g. CPUShares=1600
https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt
44. Resource Management - Memory
•MemoryAccounting=1 to enable
•MemoryLimit=
•Use K, M, G, T suffixes
•MemoryLimit=1G
https://www.kernel.org/doc/Documentation/cgroups/memory.txt
45. Resource Management - BlkIO
•BlockIOAccounting=1
•BlockIOWeight= assigns an IO weight to a specific service
(requires CFQ)
•Similar to CPU shares
•Default is 1000
•Range 10 – 1000
•Can be defined per device (or mount point)
•BlockIOReadBandwidth & BlockIOWriteBandwidth
•BlockIOWriteBandwith=/var/log 5M
https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt
53. To be clear
•Systemd maintains 99% backwards compatibility with LSB
compatible initscripts and the exceptions are well documented.
•While we do encourage everyone to convert legacy scripts to
service unit files, it's not a requirement.
•Incompatibilities are listed here:
http://www.freedesktop.org/wiki/Software/systemd/Incompatibilities/
•Converting SysV Init Scripts:
http://0pointer.de/blog/projects/systemd-for-admins-3.html
54. Unit file layout – Custom application example
[Unit]
Description=Describe the daemon
[Service]
ExecStart=/usr/sbin/[myapp] -D
Type=forking
PIDFile=/var/run/myapp.pid
[Install]
WantedBy=multi-user.target
55. [Unit] EAP Example
Description=JBoss Enterprise Application Platform
Note: If you don't define “Type=” it will be “simple” by default
[Service]
User=jboss-as
Environment=JBOSS_USER=jboss-as
Environment=JBOSS_HOME=/usr/local/EAP-6.1.1/jboss-eap-6.1
Environment=JBOSS_CONSOLE_LOG=/var/log/jbossas/console.log
ExecStart=/usr/local/EAP-6.1.1/jboss-eap-6.1/bin/standalone.sh
PIDFile=/run/jboss-as/jboss-as-standalone.pid
SyslogIdentifier=jboss-as
LimitNOFILE=102642
Slice=jboss.slice
[Install]
WantedBy=multi-user.target
58. Unit file layout – Test your unit file
•Copy the unit file
• cp [myapp].service /etc/systemd/system/
•Alert systemd of the changes:
• systemctl daemon-reload
•Start service
• systemctl start [myapp].service
•View status
• systemctl status [myapp].service
http://0pointer.de/blog/projects/systemd-for-admins-3.html
60. Journal
•Indexed
•Formatted
•Errors in red
•Warnings in bold
•Security
•Reliability
•Intelligently rotated
http://0pointer.de/blog/projects/journalctl.html
61. Journal
•Does not replace rsyslog in RHEL 7
• rsyslog is enabled by default
•The journal is not persistent by default.
•Enable persistence: `mkdir /var/log/journal`
•Stored in key-value pairs
• journalctl [tab] [tab]
•Man 7 systemd.journal-fields
•Collects event metadata along with the message
•Simple to filter
• Interleave units, binaries, etc.