Cover: A Flamegraph highlighting performance overhead due to system callsSystem calls are how user programs talk to the operating system. They include opening files, reading the current time, creating processes, and more. They’re unavoidable, but they’re also not cheap.If you’ve ever looked at a flame graph, you’ll notice system calls often show up as hot spots. Engineers spend a lot of effort cutting them down, and whole features such as io_uring for batching I/O or eBPF for running code inside...