poor gigabit ethernet performance with amd64 + sk0

[Dan Nelson]

In the last episode (Mar 25), Kenneth Culver said:
> I recently did a short file transfer over gigabit ethernet in both
> x86 and amd64. On x86 it appears the limiting factor is the laptop
> I'm transferring to. I get about 20MB/sec to the laptop in x86. But
> on amd64, I'm not sure what the limiting factor is, because I max out
> at about 2.8MB/sec with the EXACT same hardware. Here are the dmesg
> lines for that ethernet card:

Make sure you're testing ethernet speeds and not disk speeds; try
something like ttcp or tcpblast.  Even a pII/600mhz can do 50MB/sec;
any modern CPU should be able to do 90.  You might also want to do a
long test, then run systat -v to see if the CPU load or interrupts/sec
is different between x86 and amd64 modes.

-- 
	Dan Nelson
	dnelson at allantgroup.com