[CentOS] Ethernet poor performance

[Nicolas Thierry-Mieg]

Robert Moskowitz wrote:
>> That covers speed, but doesn't say anything about the duplex setting. 
>> You should see this mentioned near the Ethernet driver load lines in 
>> dmesg, too.
> 
> Do you see anything in the lines I pasted above? Those are the only ones 
> from dmesg.

try:
ethtool eth0

this will tell you the duplex mode, speed etc...