I don’t think we should parrot the syscalls-are-expensive too much. The overhead of thread syscalls is smaller than you’d think, and for say TCP and file IO our

I don’t think we should parrot the syscalls-are-expensive too much. The overhead of thread syscalls is smaller than you’d think, and for say TCP and file IO our buffers are so big that we can mitigate the amounts in practice to saturate hardware (like NICs and SSDs) limitations, no problem. The issue has more to do with thread lifecycle management, ie creating, maintaining a stack and destroying the thread. When you have very lightweight tasks, those add up and have no direct mitigations. That’s a big reason we moved runtimes into userspace. I wish I could see the perf chart of these. If anyone finds them please link. It’s important to have objective facts to base these discussions in.