The quiet colossus

The Linux kernel processes almost everything you touch.

Read time 4min 50sec

A day in the life of the Linux kernel starts just a few microseconds after midnight. The kernel, a thin layer of software that provides a consistent interface between the hardware of a computer and the systems library, is hard at work at stock exchanges in the US, where it has almost completely supplanted other alternatives. Because the kernel's licence encourages copying and modifying, the financial industry has done just that, tweaking it to perform at the utmost speed without breaking. Linux handles billions of transactions every second, passing information between processes, and managing multitasking environments for the world's financial markets. Linux is the most portable piece of software in the world. Despite being over six million lines of code, it has been ported to more hardware platforms than anything else. Its size belies its organisation, though. The functions that any kernel must provide - switching between processes, memory management, access to hardware resources and networking - are clearly separated out, with only the really low-level hardware-dependent functions differing by platform.

On the other side of the world from the US, Linux-based supercomputers are busy rendering the first few CGI shots from the upcoming Peter Jackson film The Hobbit. New Zealand-based special effects company, WETA Digital, has an army of Linux computers that they used to render the Lord of The Rings trilogy. Linux on supercomputers is also a popular choice outside the movie special effects industry. Of the top 500 fastest supercomputers on the planet, Linux runs on 92% of them, modelling complex weather systems, nuclear reactions and aircraft simulations that would make any flight sim fan drool. French manufacturer Airbus owns the 12 gigaFLOP cluster that comes in at number 42 on the list. The company won't say, but there's every likelihood its new models are prototyped and tested on this spectacular piece of computing hardware.

Apart from helping Airbus aircraft get into the sky, Linux also helps them find their way around it. Germany's entire air traffic control system runs a version of Linux from Novell. The government organisation that runs all ATC in the country needed something that was stable and reliable but that could be tuned for its needs, and SuSE Linux fit the bill. The kernel is also taking over the embedded world at a rate of knots. Because it presents a familiar layer over the hardware, developers are finding that developing standard programs written in high-level languages is faster and more convenient than the austere and specific incantations for embedded hardware.

A working day

The fastest-growing embedded systems market is the smartphone, and here, Linux truly is taking over the world. New handsets based on mobile OS Android get activated 60 000 to 70 000 times every day. In just a couple of years, Android has come from nowhere to 42% of mobile operating system market share, says Gartner. If the phones, or any other device for that matter, connect via WiFi, chances are it's a Linux kernel in the WiFi router channelling the network packets back and forth. By the time most people get to work, Linux-based mainframes have processed billions of financial transactions for banks around the world. Banking has been a mainframe mainstay for decades and Linux has become an enormously popular operating system choice in recent years for mainframe hardware. It doesn't have site licence fees and it runs standard business applications very well. Linux on IBM's System z hardware was just under a third of all installations three years ago. Within the next two, it could well move above 50%. The large database vendors like Oracle also boast very large customers running their software on Linux. Oracle surprised the world many years ago with advertisements in business magazines like The Economist for its database running on Linux, long before the kernel became as widely accepted in the enterprise as it is today.

A few minutes after most people get to work, they'll check Google and Facebook. And they'll be using Linux without knowing it. Google's Linux installation is legendary. The company isn't that forthcoming about exactly how many servers it employs in the Googleplex, but it's reported to be more than a million. These are small, stripped-down servers with built-in battery power, some memory and a CPU. Together with a customised kernel, they form the backbone of all Google's server-based products. Facebook's use of Linux is more conventional but no less impressive. Every single Facebook page is rendered by a Linux server sitting somewhere in an international web of data centres. Amazon also does its retail magic with Linux. It's hard to imagine any of these companies becoming what they have without a freely-available operating system upon which to innovate. And the rest of the Web also benefits from Linux: no higher an authority than Microsoft chairman Steve Ballmer, who admitted in 2008 that 60% of Web servers were running Linux.

And the desktop? Yes, there are few die-hard souls still using Linux as a desktop. But they're few and far between. Perhaps 2012 will be the year that it takes over? It has taken over almost everything else.

First published in the November 2011 issue of ITWeb Brainstorm magazine.

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