em driver worse then fxp driver ... why?

[Marc G. Fournier]

I have 5 servers sitting on a Linksys 10/100 switch ... 4 of the 5 are 
running fxp0 ethernet, while the 5th is running em ... and the 5th 
performs atrociously:

neptune# netstat -ni | head
Name    Mtu Network       Address              Ipkts Ierrs    Opkts Oerrs  Coll
em0    1500 <Link#1>    00:07:e9:05:1b:2e 36915965 10306 28888840     1 10858513

I've tried in bth half and full duplex mode .. full duplex, Ierrs climbs, half-duplex, Collisions climb ...

the fxp devices are all running at full-duplex, and perform quite well:

pluto# netstat -ni | head
Name    Mtu Network       Address              Ipkts Ierrs    Opkts Oerrs  Coll
fxp0   1500 <Link#1>    00:03:47:bd:67:66 105856025     0 97330263     2     0
jupiter# netstat -ni | head
Name    Mtu Network       Address              Ipkts Ierrs    Opkts Oerrs  Coll
fxp0   1500 <Link#1>    00:03:47:30:a7:1b 28832141     0 29437148     0     0
mars# netstat -ni | head
Name    Mtu Network       Address              Ipkts Ierrs    Opkts Oerrs  Coll
fxp0   1500 <Link#1>    00:e0:81:21:d7:f6 34195201     0 29871571     0     0
venus# netstat -ni | head
Name    Mtu Network       Address              Ipkts Ierrs    Opkts Oerrs  Coll
fxp0   1500 <Link#1>    00:e0:81:29:56:5b 95579278     1 87014732     1     0

Originally, it was explained that unmanaged switches tended to be 
problematic, but I'd expect some sort of uniformity in problems, but 'just 
the server with the em device' ...

So, is there a bug in the em device driver that doesn't exist on the fxp0 
devices?


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Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: scrappy at hub.org           Yahoo!: yscrappy              ICQ: 7615664