Real-time operating systems can respond to external events within a guaranteed time frame, a feature that mainstream business computing doesn't generally require but that's necessary for some areas, such as aircraft radar. But in a move that indicates the flexibility of Linux, Novell plans to begin selling the real-time variant of the open-source operating system next month.
Novell plans to announce the product at the Gartner Symposium/ITxpo on Oct. 9, said Justin Steinman, Novell's director of marketing for Linux and open-platform solutions. Novell will share the stage with , which did much of the engineering work behind the real-time version that Novell will market, he added.
Waltham, Mass.-based Novell and Duluth, Ga.-based Concurrent announced their first joint customer, Siemens Medical Solutions, which will use SLERT to power Magnetom magnetic resonance imaging (MRI) scanning products.
Wall Street also is interested, for example, in recalculating investment portfolio risk and placing trades based in response to new information, Steinman said. One unnamed investment bank told Novell that for each thousandth of a second that its trading software can act faster than competitors' software, the company would see $100 million a year in new revenue.
But while Linux is adaptable, it can't do everything. Indeed, in some more demanding parts of the real-time market, its limitations become apparent--for example those that must be able to take actions every 10 millionths of a second--with each tick of a high-precision clock.
"If there are applications that need to have 10 microseconds every single time, that's what I call hard real-time. Linux isn't going to do that," said Glenn Seiler, senior manger of Linux platforms for Alameda, Calif.-based.
Nevertheless, Wind River and others such ashave been working to give Linux a snappy response.
And one company believes a more esoteric, hybrid approach provides combines real-time abilities with Linux software benefits. FSMLabs, a small company based in Socorro, N.M., sells a product called RTLinux that pairs the company's proprietary RTCore operating system for real-time tasks with Linux to run other software, such as the user interface.
Real-time operating systems are one component of the vast and diverseand to and .
Linux is increasingly popular as an embedded operating system. Wind River, Concurrent and LynuxWorks all have embraced Linux despite having competing proprietary products of their own.
One of the family
SLERT will be one of several members of the , which already includes a server and desktop version of Linux introduced in July. The company is betting that an aggressive Linux strategy will help the company improve its overall financial performance and compete better with the top Linux seller, Red Hat.
SLERT is a joint effort. Novell, which has better name recognition and a larger sales force, will work on marketing SLERT, Steinman said. Concurrent has years of embedded operating system experience and helped with extensions to Linux that provide the real-time support. The two companies will share revenue, Steinman said.
While some real-time operating systems are found in small computing devices, SLERT is geared for larger systems such as multiprocessor servers. On one test on that type of system running the Ingres database over 28.8 million transactions, SLERT responded as fast as 11 millionths of a second and no slower than 27 millionths of a second, Novell said.
Novell's real-time Linux leader is Moiz Kohari, founder of the now-extinct. (The company had some influential employees: Red Hat's chief technology officer, Brian Stevens, also had been Mission Critical Linux's CTO.)
The product won't be purchased the same way as Novell's other Linux versions, however. "Setting it up does require a consulting engagement" from Novell, which installs and tunes the software, Steinman said. "It isn't something you can take off the shelf and get up and running."
UMB Financial Corporation is another SLERT customer, which uses the software on its identity management system.
One customer that needs a real-time operating system is Concept Overdrive in Burbank, Calif., which builds the control systems for creatures in the hydraulically operated alien in "Alien vs. Predator" or the dolls in "Seed of Chucky."
RTLinux was well-adapted to the challenge because it's flexible enough to handle multimedia tasks such as playing recorded speech at the same time it controls the movement of a robot's mouth, said Concept Overdrive Founder Steve Rosenbluth.
The status of the motors must be updated 60 times per second, with each interval exactly timed. If one interval is slightly longer than the next--a problem called "jitter"--the motors and actuators inappropriately slow down, then speed up by small amounts, he said.
"Timing jitter will manifest itself in physical jitter of the actuator," Rosenbluth said. Jitter, combined with the weight and inertia from robotic mechanics, "causes visual vibration and shaking."
Timing precision is even more important for CableCam, another Concept Overdrive customer that uses RTLinux to control cameras that swoop over stadiums, between buildings and through trees.
A real-time response also is necessary for people--the directors and actors and puppeteers shooting scenes in movies or advertisements.
"Puppeteers are actors. They're reacting to what else is in the scene--lighting, human beings. You want what feels instantaneous to a human being," Rosenbluth said. "When an operator moves a joystick, you want the electromechanical actuator to move instantaneously and without bumps or glitches."
Mainstream Linux going real-time?
Mainstream Linux must be adapted for the real-time approach, but Wind River sees real-time improvements on the Linux horizon.
The company employs a Linux modification written by a Red Hat programmer, Ingo Molnar, even though it is outside the mainstream Linux development version maintained by Linux leader Linus Torvalds.
Molnar's "Preempt RT" approach changes the heart of Linux, called the kernel, so many ordinary events become opportunities for interruption, Seiler said. With it, Linux's maximum response rate drops from about 2 thousandths to 30 millionths of a second, he said.
The biggest hitch is that the patch imposes requirements on operating system components called device drivers, which handle communications between the kernel and devices such as hard drives or network cards.
Those drivers must be adapted to work on multiprocessor machines for the Preempt RT patch to work, Seiler said. That's not a problem for computers with mainstream x86 chips such as Intel's Pentium, but it can be for MIPS or PowerPC chips in the embedded realm, he said.
"That is the rough edge around this," Seiler said. "Everybody writes good x86 drivers. It's the dominant platform for Linux. But when you start getting into MIPS and PowerPC architectures, then the state of what's available in the community isn't perhaps as robust or mature as what's available in x86. A lot of the drivers were written quick and dirty."
Part of Wind River's work in selling its embedded Linux version is making sure the drivers support the Preempt RT patch, he said.
But soon real-time could become more widespread. Seiler believes Molnar's patch will be accepted soon into the mainstream Linux kernel, currently at version 2.6.17.
"I suspect that's going to happen within the next couple versions--2.6.19 or 20," Seiler said. "That's my reasonable, intelligent guess."