receive errors

Hi,

I am running a benchmark that uses a UDP socket to send small packets
(20 bytes) from on side to the other side. I experience packet loss
reported by the benchmark and I can see that it matches what I see with
netstat:

[root@sw174 opt]# netstat -us
Udp:
    26971289 packets received
    7 packets to unknown port received.
    32615 packet receive errors
    155761284 packets sent

Can someone please direct to the source code that detects such receive
errors and/or suggest why such a thing could happen?

Thanks
Eli