You’re replying to a comment about context switches, not syscalls. Linux on x86 cannot do tens of millions of context switches per second per core. (I expect that, at high clock speed, carefully tuned, under ideal and possibly unrealistic conditions, you might get 2M/s — it’s been a while since I benchmarked this.)

But this is silly — shared nothing will have no substantial difference in the rate of context switches (or of syscalls) compared to a thread-per-core-shared-everything architecture. The architecture that actually loses is many-threads-per-core if it ends up in a small-batch mode in which it context switches once per request or so.