Packet coalescing is the grouping of packets as a way of limiting the number of receive interrupts and, as a result, lowering the amount of processing required.
Packets matching receive filter parameters are cached and released together when any of the following occurs:
- the cache is filled
- an expiration timer is reached
- a packet is received for a different machine and is outside the coalescing filter
- the device reaches its minimum low water mark
- an interrupt event message is received, such as a send completion.
Data sent destined for computers A and B on a network where C also resides will be grouped together so that they are consistently passed along to A and B without checking each packet or forwarding all requests to all computers. That process prevents C from being needlessly hit with unsolicited traffic that it would have to filter for its own requests.