Although you are technically correct in that the cost of system calls on most systems is high, your post also implies to a casual reader that the cost is fundam

Although you are technically correct in that the cost of system calls on most systems is high, your post also implies to a casual reader that the cost is fundamental. This is not true. As demonstrated in the benchmark, the hardware cost of systems calls/trapping is quite low. Even accounting for hardware workarounds (which were not even known about when the common consensus decided system calls were slow), excepting the case of hardware virtualization which has much more expensive mitigations, the fundamental cost is a fraction of the actual cost. The majority of the cost (~90+%) is actually due to software. In the system call case this is the implementation of the system call. In the context switch case this is usually the cost of the scheduling decision. These operations take material amounts of time and access memory which evicts user caches. It is in speeding up the software component that real gains can be made. This is not to say that system calls could ever be made "free" since function calls/loads/stores will still be ~100x faster, but the cost would probably be ~10% of the current cost if they software component could magically be made instant. As an example of what I am talking about, there is this talk by Google from 2013 [1] which describes a "fast context switch" system call (benchmark at 18:40). This "context switch" knows what it is switching to which lets it bypass the scheduling decision in normal context switches. As a result it takes ~170 ns (which is pretty close to the hardware cost mentioned in the OP) vs 2000 ns of a normal context switch. I could go into more detail as to some of the causes of the underlying software costs, but that is a discussion for another time, so I will just leave this off with summarizing my point. tl;dr: System calls are slow. It is due to the software implementing them, not the hardware. [1]: https://www.youtube.com/watch?v=KXuZi9aeGTw https://www.youtube.com/watch?v=KXuZi9aeGTw