> Modern OSes, complicated software stacks, preemptive multi-tasking, and the need for flexible general purpose usage, eat up a huge percent (I'd say well over

> Modern OSes, complicated software stacks, preemptive multi-tasking, and the need for flexible general purpose usage, eat up a huge percent (I'd say well over ~70%) of the usable computing capacity in the devices we deal with every day. I think a big part of it is security. Having to isolate address spaces is expensive. (Sometimes I like to imagine being able to run a unikernel OS where applications are written in something like safe Rust, everything runs in the same address space, and the OS delegates enforcing memory separation to a trusted compiler. So, things like writing to disk or the network are just regular function calls with no context switch overhead. In this model, unsafe code is treated sort of the way we treat kernel code or setuid binaries in Linux: regular users aren't allowed to run arbitrary unsafe code. With Spectre, I don't know if this sort of approach is still feasible on modern processors, or if it's possible for a compiler to guarantee that the compiled code is not susceptible to any known side-channel attacks.)