Category: Network

Moore’s Law needs a hug. The days of stuffing transistors on little silicon computer chips are numbered, and their life rafts — hardware accelerators — come with a price.

When programming an accelerator — a process where applications offload certain tasks to system hardware especially to accelerate that task — you have to build a whole new software support. Hardware accelerators can run certain tasks orders of magnitude faster than CPUs, but they cannot be used out of the box. Software needs to efficiently use accelerators’ instructions to make it compatible with the entire application system. This translates to a lot of engineering work that then would have to be maintained for a new chip that you’re compiling code to, with any programming language.

Now, scientists from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) created a new programming language called “Exo” for writing high-performance code on hardware accelerators. Exo helps low-level performance engineers transform very simple programs that specify what they want to compute, into very complex programs that do the same thing as the specification, but much, much faster by using these special accelerator chips. Engineers, for example, can use Exo to turn a simple matrix multiplication into a more complex program, which runs orders of magnitude faster by using these special accelerators.

Unlike other programming languages ​​and compilers, Exo is built around a concept called “Exocompilation.” “Traditionally, a lot of research has focused on automating the optimization process for the specific hardware,” says Yuka Ikarashi, a PhD student in electrical engineering and computer science and CSAIL affiliate who is a lead author on a new paper about Exo. “This is great for most programmers, but for performance engineers, the compiler gets in the way as often as it helps. Because the compiler’s optimizations are automatic, there’s no good way to fix it when it does the wrong thing and gives you 45 percent efficiency instead of 90 percent.”

With Exocompilation, the performance engineer is back in the driver’s seat. Responsibility for choosing which optimizations to apply, when, and in what order is externalized from the compiler, back to the performance engineer. This way, they don’t have to waste time fighting the compiler on the one hand, or doing everything manually on the other. At the same time, Exo takes responsibility to ensure that all of these optimizations are correct. As a result, the performance engineer can spend their time improving performance, rather than debugging the complex, optimized code.

“Exo language is a compiler that’s parameterized over the hardware it targets; the same compiler can adapt to many different hardware accelerators,” says Adrian Sampson, assistant professor in the Department of Computer Science at Cornell University. “ Instead of writing a bunch of messy C++ code to compile for a new accelerator, Exo gives you an abstract, uniform way to write down the ‘shape’ of the hardware you want to target. Then you can reuse the existing Exo compiler to adapt to that new description instead of writing something