LXer: This week at LWN: Interrupt mitigation in the block layer
 

Published at LXer:

Network device drivers have been using the increasingly misnamed NAPI ("new API") interface for some time now. NAPI allows a network driver to turn off interrupts from an interface and go into a polling mode. Polling is often seen as a bad thing, but it's really only a problem when poll attempts turn up no useful work to do. With a busy network interface, there will always be new packets to process; "polling," in this situation, really means "going off to deal with the accumulated work." When there is always work to do, interrupts informing the system of that fact are really just added noise. Your editor likes to compare the situation to email notifications; anybody who gets a reasonable volume of email is quite likely to turn such notifications off. They are distracting, and there is probably always email waiting whenever one gets around to checking.

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