tcp/udp performance

[Danny Braniss]

ever since 6.1 I've seen fluctuations in the performance of
the em (Intel(R) PRO/1000 Gigabit Ethernet).

	    motherboard			OBN (On Board NIC)
	    ----------------		------------------
	1- Intel SE7501WV2S		Intel 82546EB::2.1
	2- Intel SE7320VP2D2		INTEL 82541
	3- Sun Fire X4100 Server	Intel(R) PRO/1000

test 1: writing to a NetApp filer via NFS/UDP
	   FreeBSD		Linux
		      MegaBytes/sec
	1- Average: 18.48	32.61
	2- Average: 15.69	35.72
	3- Average: 16.61	29.69
(interstingly, doing NFS/TCP instead of NFS/UDP shows an increase in speed of
around 60% on FreeBSD but none on Linux)

test2: iperf using 1 as server:
		FreeBSD(*)	Linux
	             Mbits/sec
	1- 	926		905 (this machine was busy)
	2-	545		798
	3- 	910		912
 *: did a 'sysctl net.inet.tcp.sendspace=65536'


So, it seems to me something is not that good in the UDP department, but
I can't find what to tweek.

Any help?

	danny