Nowdays they don't use INT 0x80 for syscalls anymore. It's faster to use something called "virtual system calls" from what I understand (I am not a kernel dev, so don't quote me). It's just what it sounds like. If you ldd a linux binary, you'll see a shared object called `linux-gate.so` or `linux-vdso.so` (it's been renamed a few times). This file doesn't actually exist. It's an imaginary library that exists as the doorway into the kernel for making these calls.
> For example, x86 processors usually call interrupt 80, while x64 processors use the syscall processor instruction.
It's 0x80, or 128 in decimal.