Linux range of use
Linux kernel-based operating systems have found wide adoption and a very far-reaching range of use. All the advantages and benefits of free and open-source software apply to the Linux kernel itself and also to most of the rest of the system software.
Contents
Linux on the desktop
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The common human interface devices (HIDs) available for desktop computers, laptops and similar devices determine the design of the (graphical) human-computer interface implemented into software. There are a couple of software packages to choose among, when building an accordingly designed graphical user interface. The generic input driver for the Linux kernel is evdev, but here are several input methods implemented as middleware, i.e. on top and not as part of the Linux kernel.
Linux as a gaming platform
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As the actual adoption is proving, the Linux kernel is also suitable as a gaming platform. Of course, additional software is necessary to either augment a typical desktop installation to be suitable as a gaming platform, or to create a Linux-based operating system for the sole purpose of being a gaming platform.
Linux for servers and clusters
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Servers
There is an abundance of server software (cf. client–server model) supporting various communications protocols, such as e.g. HTTP (web server), SMTP (mail transfer agents), POP3 and IMAP (e-mail server), LDAP, SMB/CIFS (Samba), SNMP (for system and network monitoring), SIP, various routing protocols that runs, partially exclusively, on top of the Linux kernel.
Some software bundles, also called solution stacks, have been that widely adopted, that their acronyms have become well known, e.g.
- LAMP – for dynamic web sites
- LYME and LYCE – for dynamic web sites
Linux kernel-based operating systems also serve as basis for cloud computing solutions, such as:
- LEAP – for cloud computing
- OpenStack – for infrastructure as a service (IaaS), the controller nodes run only on a Linux operating system
And of course all three types of virtualization (hardware-based, software-based and paravirtualization) have been implemented by a couple of projects, that run Linux, some being Linux exclusive. The Linux kernel itself has been customized, adapted and hardened to various scenarios, especially to the operation of a bastion host. Some were already mainlined, some are being developed and maintained out-of-tree.
Linux kernel-based operating systems are still employed as routing servers on both, server computers and also on commodity hardware, in cases where professional routing equipment such as Cisco Catalyst, are either overkill or simply too expensive. Components of the Linux kernel, such as Netfilter or the Linux network scheduler, in conjunction with the available free and open-source routing daemons BIRD, B.A.T.M.A.N., Quagga and XORP fulfill the task very well. Very low-cost and low-performance routing can be even achieved by wireless routers running OpenWrt.
The anonymity routing solution Tor is cross-platform and not exclusive to Linux.
Clusters
Components of the Linux kernel, like e.g. LVM, are well suited to support computer clusters. There is also software for the management of clusters, e.g. Pacemaker, Linux-HA, DRBD, oVirt, openQRM, Ganeti, Eucalyptus, AppScale, or OpenNebula.
For both single system image and multi system image clusters, there are at least LinuxPMI, OpenSSI, Open-Sharedroot (Diskless shared-root cluster), and Kerrighed available.
Virtualization
There are three solutions for OS-level virtualization: Linux-VServer, LXC and OpenVZ, which offer similarities to FreeBSD jails and Solaris Containers.
A Linux operating systems runs virtualized on Xen, a micro-kernel-type hypervisor published under the same license as the Linux kernel (GNU GPL-2.0), and with KVM it is possible to turn the Linux kernel into a hypervisor.
For the managing there are libvirt, libguestfs and several utilities building upon them, as well as a couple of other programs.
OpenStack controller nodes run exclusively on Linux, while compute nodes are cross-platform. Related software projects are Nimbus, Ganeti, AppScale, Distributed Replicated Block Device, OpenNebula, Eucalyptus or openQRM.
Linux for mobile devices
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One of the best known Linux-based operating systems for mobile devices, such as smartphones, is the Android (operating system). Android employs a modified Linux kernel and combines it with libbionic instead of the glibc, SurfaceFlinger as display server, and some other replacements specifically written for this purpose.
Many mobile devices have a touchscreen as their sole human interface device (HID). The GUI and partly the middleware of the operating system has to be adapted as to enable software designers to create an according human-computer interface.
Linux for embedded systems
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There are actively maintained patches that transform the Linux kernel into a real-time kernel. That way Linux kernel gained a wide adoption as a kernel for operating systems driving embedded systems. Minimally, such an operating system includes a more or less modified Linux kernel, µClibc and BusyBox.
A non-RTOS example, and at the same time a Linux distribution, is OpenWrt. OpenWrt is intended to be employed on CPE devices like wireless routers. Another example is Rockbox, an operating system for portable media players based on μClinux.
Linux for supercomputers
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All the fastest supercomputers in the decade since the Earth Simulator supercomputer, have used Linux. Linux also ran on the first teraflops supercomputer, ASCI Red in 1997, and on IBM Roadrunner in 2008, which was the first petascale supercomputer.
As of November 2014[update], 485 or 97% of the world's fastest supercomputers run an operating system based on the Linux kernel; this percentage also translates to over 98% of the total core count or overall performance. Remaining 3% run some Unix variant (which is AIX for all of them except one), with one supercomputer running Windows and one with a "mixed" operating system.[1] Within those 97% are the most powerful supercomputers including those ranking as the top ten.
Since November 2014, Windows Azure[2] cloud computer is no longer on the list of fastest supercomputers (its best rank was 165 in 2012), leaving the Shanghai Supercomputer Center's "Magic Cube" as the only Windows-based supercomputer, running Windows HPC 2008 and ranked 360 (its best rank was 11 in 2008).[3]
