em driver worse then fxp driver ... why?

[Eli Dart]

In reply to "Marc G. Fournier" <scrappy at hub.org> :

> 
> 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  Co
 ll
> em0    1500 <Link#1>    00:07:e9:05:1b:2e 36915965 10306 28888840     1 10858
 513
> 
> I've tried in bth half and full duplex mode .. full duplex, Ierrs climbs, hal
 f-duplex, Collisions climb ...

I would expect collisions on a half-duplex link -- this is not 
necessarily a Bad Thing.

It could be that the unmanaged switch is unable to talk full-duplex 
to the em interface for some reason.....

Do you have throughput numbers for the two configs (half-duplex em, 
full-duplex em, and full-duplex fxp)?

		--eli


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