Interrupt
A signal from hardware that asks the system to turn its attention to something now.
Glossary
Polling
Repeatedly checking whether a component needs attention, rather than waiting to be told.
In one line
Repeatedly checking whether a component needs attention, rather than waiting to be told.
Also calledrepeated checking
Polling is the act of asking, over and over, is there anything for me yet? It is simple and predictable, but it can waste effort when the answer is usually no. The system spends time checking even when nothing has changed.
The alternative, an interrupt, lets a component speak up only when it has something. Drivers choose between the two depending on what suits a particular component best. Each approach has its place, and neither is right for every situation.
Polling shines when something needs checking very frequently and almost always has new work waiting. In that case the constant asking is rarely wasted, and its simple, steady rhythm can be easier to manage than handling a flood of separate signals.
Polling falters when checks come back empty most of the time, because the effort of asking is then spent for nothing. Choosing between polling and waiting to be told is a small but meaningful decision that shapes how efficiently a part is served.
In practice
In practice, polling is like repeatedly checking the mailbox to see whether the post has arrived. If you check far more often than mail appears, most trips are wasted. Sometimes it is better to wait for a knock instead, which is exactly the choice a driver weighs.
