One important distinction in system calls is between “fast” and “slow” system calls, which affects how they interact with signal handling, process scheduling, and overall system performance. Slow System CallsFast System CallsFast system calls are operations that can be completed immediately without requiring the kernel to wait for external events. Non-blocking System Calls (Fast)These system calls return immediately, only requiring CPU time. Slow System Call ImplementationSlow system calls have a more complex implementation:User code invokes the system call. Modern operating systems have evolved sophisticated mechanisms for dealing with different types of system calls, from simple fast calls to complex asynchronous operations.