[$] Batch processing of network packets

It has been understood for years that kernel performance can be improved bydoing things in batches. Whether the task is freeing memory pages,initializing data structures, or performing I/O, things go faster if thework is done on many objects at once; many kernel subsystems have beenreworked to take advantage of the efficiency of batching. It turns out,though, that there was a piece of relatively low-hanging fruit at the core of the kernel's networkstack. The 4.19 kernel will feature some work increasing the batching ofpacket processing, resulting in some impressive performance improvements.