Here is a bundle of questions I've been conjuring up during my stay at the SC11 Supercomputing conference this year:
Why is there a saying that "we won't be able to enter the era of exascale computing just by adding more and more Xeons"? Why do we need the GPU/Accelerator architecture to achieve what we want?
Why can't compilers automatically map high-level code to new architectures? For instance, instead of having to learn CUDA to reprogram all your applications to run in massive parallel on nvidia GPUs, why not just write in C, and let the compiler researchers do the job of developing a compiler that will conveniently parallelize the program for you? Maybe that was a bad example, and if anyone wants to provide their own, that's certainly welcome :)
What makes a good compiler a good compiler?
How does High Performance Computing affect the economy, and why is there such a big drive (especially between the three countries China, Japan, and the USA) to create marginally faster supercomputers over each other year after year?
What draws the line between a 'supercomputer' and a 'cluster', or is there not really a distinction?
Any other personal thoughts or ruminations to add on top of these are welcome.