November 18, 2003

Formula 1 racer's secret: 1,000 horsepower and a Linux cluster

Author: Chris Gulker

Aerodynamics are as important to modern Formula 1 race cars as they are to jet fighters. That's why the BMW Williams F1 team turn to a Linux cluster when they need to get a bit more out of their 3-litre, 1,000-horsepower, 1,320-lb. FW25 car.

Formula 1 cars are highly reliant on technology: indeed, the BMW Williams car won't even start unless it's connected to a ruggedized HP laptop. Formula 1 teams spend tens of millions of dollars on aerodynamics alone. The goal is to optimize the ratio between downforce, which helps cars corner, and drag, which slows them down. Modern teams refine their cars for every race, adding larger front and rear inverted wings for twisty tracks where cornering speed is important, and reducing them for tracks with long straightaways where minimizing drag is paramount.

Computational fluid dynamics is the name given to the field of study that involves modeling air flows around objects like race cars using computers. Designers in industries as diverse as aviation, shipbuilding, and refinery construction have used CFD to model creations, that, in practice, would be very difficult and expensive to build, test, and modify.

But CFD isn't cheap either: it's an example of a fine-grained computational problem (see Shared vs. distributed memory in large Linux clusters) and typically requires very serious hardware resources to run simulations in a useful amount of time. The last generation of supercomputers sometimes required weeks to model the flow of gas through a valve, for example.

In BMW Williams's case, "useful" meant overnight. With F1 races every week, they wanted to reduce the amount of time it took to design, test, and refine aerodynamic designs. BMW Williams' solution came from HP, one of the team's top-line technology sponsors, in the form of an HP XC Linux cluster.

"BMW Williams needed a 3x speed-up in aerodynamic modeling," says Dr. Tim Bush, manager of high performance technical computing for HP EMEA (Europe, Middle East, and Africa). The solution was a Linux cluster using "hundreds" of processors and a low-latency, high-speed interconnect. Formula 1 racing is so competitive that Bush can't say how many processors or the kind of networking or even what Linux distribution they run, lest that information give competitors an edge.

He can say that the nodes are two-processor HP ProLiant DL360 servers.

"The machine allows smart guys to ask what-if questions and get their answers overnight," said Bush. "It dramatically shortens the development cycle. The time it takes to design and test something and get it on the car is dramatically compressed -- from 3 weeks to 5 days."

And the techniques that the BMW Williams engineers have developed are useful elsewhere, according to Bush. "If you drive a BMW convertible at 80 miles an hour, you get a lot less buffeting and noise with the roof down, because these guys use these kinds of simulations even to design road cars," Bush said. "It's becoming a mainstream technology."

Just as engineers get a lot more horsepower from a 3-litre racer than a passenger car, the Formula 1 team typically makes much higher fidelity aerodynamic models than is common for passenger car designers. And this in turn is computationally much more expensive, which translates to higher hardware costs. Enter Linux.

"The initial outlay was definitely less for the Linux system," said Bush. "You do have the ongoing expense of managing hundreds of system images," he said, noting that any well-trained Linux admin could keep the cluster going. "There's also the fact that CFD models run very well on Xeon clusters," he said.

"There is a very strong correlation between the performance of aerodynamics simulations and on-track performance. After the system was delivered in May, they began to make major strides in performance," Bush said. Indeed, BMW Williams finished 2nd in this year's standings, after trailing farther back earlier in the year.

"They chose Linux as a strategic platform," Bush said. "By the end of the season, both drivers were competing for the championship."

Linux fans will be cheered to learn that BMW Williams, with a budget large enough to buy almost anything, chose Linux. They came in second this time around, but just wait 'til next year.

Chris Gulker, a Silicon Valley-based freelance technology writer, has authored more than 130 articles and columns since 1998. He shares an office with 7 computers that mostly work, an Australian Shepherd, and a small gray cat with an attitude.

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