When using strace, what does the poll() system call do on a socket's file descriptor?

Issue

• Using the strace utility to inspect a userspace processes' systemcalls, a file descriptor which is a socket has the poll() system call utilized frequently, like so:

17177 15:13:49.801165 poll([{fd=281, events=POLLIN|POLLRDNORM}, {fd=365, events=POLLIN|POLLRDNORM}, {fd=347, events=POLLIN|POLLRDNORM}, {fd=353, events=POLLIN|POLLRDNORM}, {fd=330, events=POLLIN|POLLRDNORM}, {fd=348, events=POLLIN|POLLRDNORM}, {fd=351, events=POLLIN|POLLRDNORM}, {fd=352, events=POLLIN|POLLRDNORM}, {fd=678, events=POLLIN|POLLRDNORM}, {fd=355, events=POLLIN|POLLRDNORM}, {fd=339, events=POLLIN|POLLRDNORM}, {fd=363, events=POLLIN|POLLRDNORM}, {fd=378, events=POLLIN|POLLRDNORM}, {fd=510, events=POLLIN|POLLRDNORM}, {fd=533, events=POLLIN|POLLRDNORM}, {fd=532, events=POLLIN|POLLRDNORM}, {fd=534, events=POLLIN|POLLRDNORM}, {fd=535, events=POLLIN|POLLRDNORM}, {fd=536, events=POLLIN|POLLRDNORM}, {fd=537, events=POLLIN|POLLRDNORM}, {fd=538, events=POLLIN|POLLRDNORM}, {fd=539, events=POLLIN|POLLRDNORM}, {fd=540, events=POLLIN|POLLRDNORM}, {fd=541, events=POLLIN|POLLRDNORM}, {fd=542, events=POLLIN|POLLRDNORM}, {fd=543, events=POLLIN|POLLRDNORM}, {fd=544, events=POLLIN|POLLRDNORM}, {fd=545, events=POLLIN|POLLRDNORM}, {fd=546, events=POLLIN|POLLRDNORM}, {fd=547, events=POLLIN|POLLRDNORM}, {fd=548, events=POLLIN|POLLRDNORM}, {fd=549, events=POLLIN|POLLRDNORM}, {fd=550, events=POLLIN|POLLRDNORM}, {fd=551, events=POLLIN|POLLRDNORM}, {fd=553, events=POLLIN|POLLRDNORM}, {fd=555, events=POLLIN|POLLRDNORM}, {fd=554, events=POLLIN|POLLRDNORM}, {fd=556, events=POLLIN|POLLRDNORM}, {fd=557, events=POLLIN|POLLRDNORM}, {fd=558, events=POLLIN|POLLRDNORM}, {fd=559, events=POLLIN|POLLRDNORM}, {fd=560, events=POLLIN|POLLRDNORM}, {fd=561, events=POLLIN|POLLRDNORM}, {fd=562, events=POLLIN|POLLRDNORM}, {fd=568, events=POLLIN|POLLRDNORM}, {fd=609, events=POLLIN|POLLRDNORM}, {fd=552, events=POLLIN|POLLRDNORM}, {fd=564, events=POLLIN|POLLRDNORM}, {fd=566, events=POLLIN|POLLRDNORM}, {fd=566, events=POLLIN|POLLRDNORM}