Unstable ARP responses times

[Dan Nelson]

In the last episode (May 13), Bartosz Woronicz said:
> Since I moved from 7.3-stable to 8.2-stable I go strange long responses 
> of arp, with arping.
> I.e.
> root at Korbotron82|pts/3|13:35:35|/home/mastier # arping -i vlan92 
> 79.110.194.140
> ARPING 79.110.194.140
> 60 bytes from 00:15:17:a2:ea:38 (79.110.194.140): index=0 time=1.579 msec
> 60 bytes from 00:15:17:a2:ea:38 (79.110.194.140): index=1 time=653.326 msec
> 60 bytes from 00:15:17:a2:ea:38 (79.110.194.140): index=2 time=7.153 usec

arping has a usleep(1) call in its read loop, which can cause delays like
this if there are other processes running and the scheduler decides to run
another process.  Try removing the usleep(1) on line 916 of arping.c and see
if that helps.  The best solution would be to use the kernel-provided
timestamps from the pcap header, rather than calling gettimeofday() in
userland.  If you run "tcpdump arp", you should be able to see the packet
timestamps as the kernel sees them.

-- 
	Dan Nelson
	dnelson at allantgroup.com