More correct title would be "All 500 of the world's top 500 supercomputers are running Linux kernel". Of course nobody uses off-the-shelve Ubuntu (or another di

More correct title would be "All 500 of the world's top 500 supercomputers are running Linux kernel". Of course nobody uses off-the-shelve Ubuntu (or another distro) to power supercomputer. I'm not an expert, but I bet that it's heavily modified Linux kernel with custom userspace optimized for a given task in mind (scientific calculations, simulations etc.)