#33 Limit the queue within MacIP LL

[Andrew Roughan]

The MacIP Link Layer accepts packets via interrupt and continues to grow the queue to the limit of available memory. As the queue grows, the time taken to process the queue increases which slows processing speed down.
After running a throughput test, it can take a <long> time for existing packets in the queue to be processed.

Geoff Body suggests limiting the queue in some way. e.g.
- limiting packet buffering to a set size (e.g. 16KB) and dropping packets if there is no space
- creating fixed size circular queue