. When a TCP connection is
established, it is moved from the partial listen
queue to the listen queue. We insert the socket at the position
corresponding to its priority in the listen queue.
Since the server
process always removes the head of the listen queue when calling
, this approach provides better service, i.e. lower
delay and higher throughput, to connections with higher priority.
Figure 2 shows the implementation of a prioritized
listen queue. A special data structure used for maintaining socket QoS
attributes stores an array of 
. Each priority
pointer points to the 
socket of the corresponding priority
class. This allows efficient socket insertion -- a new socket is
always inserted behind the one pointed to by the corresponding
priority pointer.
:
