Waiting for I/O operations with poll() and select()

In a complex system such as a modern computer, it's quite common to have several useful peripherals to acquire information about the external environment and/or the system's status. Sometimes, we may use different processes to manage them but we may need to manage more than one peripheral at a time, but with just a single process.

In this scenario, we can imagine doing several read() system calls on each peripheral to acquire its data, but what happens if one peripheral is quite slow and it takes a lot of time to return its data? If we do the following, we may slow down all data acquisition (or even lock it if one peripheral doesn't receive new data):

fd1 = open("/dev/device1", ...);
fd2 = open("/dev/device2", ...);
fd3 = open("/dev/device3", ...);

while (1) {
    read(fd1, buf1, size1...