RTNETLINK answers: File exists when using netem with tc

Question

So I simply get this error when I enter this command in my master VM:

 sudo tc qdisc add dev eth0 root netem delay 97ms
RTNETLINK answers: File exists

Any idea how that could be fixed?

I am running this command in Ubuntu:

uname -a
Linux anmol-vm1-new 3.13.0-46-generic #79-Ubuntu SMP Tue Mar 10 20:06:50 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
ubuntu@anmol-vm1-new:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.2 LTS
Release:    14.04
Codename:   trusty

Here's the content of /etc/network/interfaces file:

auto lo
iface lo inet loopback
source /etc/network/interfaces.d/*.cfg


ls /etc/network/interfaces.d/
eth0.cfg

And here's what I have in /etc/network/interfaces.d/eth0.cfg

# The primary network interface
auto eth0
iface eth0 inet dhcp

Additionally I get these errors:

ubuntu@anmol-vm1-new:/home/hadoop/yarnpp/workloads/RESULTS$ tc qdisc change dev eth0 root netem delay 100ms
RTNETLINK answers: Operation not permitted
ubuntu@anmol-vm1-new:/home/hadoop/yarnpp/workloads/RESULTS$ sudo tc qdisc change dev eth0 root netem delay 100ms
RTNETLINK answers: Invalid argument

In reference you might also want to look at this StackOverflow question I had asked for limiting the bandwidth.

ifconfig -a
eth0      Link encap:Ethernet  HWaddr fa:16:3e:b4:22:7c  
          inet addr:10.0.1.190  Bcast:10.0.1.255  Mask:255.255.255.0
          inet6 addr: fe80::f816:3eff:feb4:227c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1454  Metric:1
          RX packets:603022138 errors:0 dropped:0 overruns:0 frame:0
          TX packets:132788011 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:633486216278 (633.4 GB)  TX bytes:798520828666 (798.5 GB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:367293839 errors:0 dropped:0 overruns:0 frame:0
          TX packets:367293839 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:547056723183 (547.0 GB)  TX bytes:547056723183 (547.0 GB)

Solution 1

The solution was the following:

sudo tc qdisc del dev eth0 root
sudo tc qdisc add dev eth0 root netem delay 100ms

Solution 2

shorter solution:

sudo tc qdisc replace dev eth0 root netem delay 100ms