> Sufficiently different to not be a problem? As I understand it system calls don't usually rely on the stack whereas C calls do, and it is the stack mismatch b

> Sufficiently different to not be a problem? As I understand it system calls don't usually rely on the stack whereas C calls do, and it is the stack mismatch between C and Go that is the issue. Switching the stack only takes a few machine instructions. Most of the overhead comes from runtime bookkeeping, in contrast ABI translation and switching the stack take a trivial amount of code and time. > Maybe for user called function...but if every single system call had to swap out the stack surely that would have a pretty heavy impact... As mentioned, on some platforms, for example Solaris and Windows, this always happens, and even on other platforms, in some conditions, it happens too. Not to mention that the runtime switches stacks for its own reasons all the time. The overhead is totally dwarfed by the cost of doing system calls in the first place.