64-bit vs multicore processors

Given the choice between 64-bit applications or a multicore architecture, most developers will now choose the 64-bit platform. One reason for this is that when developing 64-bit applications, coders can use double precision to verify the algorithms used in the software.

Software designed for the 64-bit platform also has a longer shelf life because more and more end-users will choose laptops and desktops with a 64-bit operating system in the next few years. This was not true just a few years ago, when the vast majority of applications and operating systems were running in 32-bit.

"Engineers are forever creating larger models," says Barbara Hutchings, who is one of the directors at simulation and design-analysis software company Ansys. "Larger models are driven by a need for higher fidelity, which translates into a bigger simulation model that requires more RAM. With 32-bit, there's a limit of two million cells, or depth of field. That was a good sized model about three or four years ago.

Today, it's not unusual for there to be 10 million, 200 million or a billion cells. We now access memory in a distributed fashion, using cluster computing with multiple processors, each of which has its own processes running. However, not every bit of the simulation task can be achieved with cluster distribution. Every time the procedure needs to sit at the single process, the 32-bit limit hurts. 64-bit improves that [situation] greatly."

"You can use 64-bit values in a 32-bit environment, but you take a huge performance hit because of the different sets of registers that are needed to run extended 64-bit data ranges," adds Mike Sanor, a technician at Micron.

"Some 64-bit operations are not even supported in a 32-bit operating system. For example, a 32-bit operating system can only use 32-bit adds, subtracts, multiplies and divides, so the compiler has to do that for you. You can reduce the amount of calculations the system has to do when you use a 64-bit system. Rather than processing the 64-bit registers sequentially in a 32-bit operating system, the 64-bit OS handles the registers in 64-bit 'chunks'."

The promise of 64-bit computing has certainly taken a long time to mature. The release of Adobe Creative Suite 4 is a major milestone, as it means that 64-bit apps have finally gone mainstream. The release of other 64-bit software, including Maya and Revit, adds to the momentum of the movement.

64-bit applications can access a larger memory envelope, use double precision for programming routines, allow engineers and photographers to apply many gigabytes of RAM to a single application process and let game developers run multiple toolkits on a single workstation. In the future, all drivers and software will be 64-bit. That future is almost here.

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First published in PC Plus issue 279

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