Understanding the Network Interface Card

It will cache up to three slots like this, and, like always, when it grabs a job off the queue, it increments the Unload Pointer. The 3B2 kernel driver doesn’t actually populate those queues with jobs for many milliseconds, so the NI card just loops, watching them. By the time the kernel driver has reached the last slot in the queue, the card has already taken and cached three jobs for later use.

Source: loomcom.com