Arch Linux

allsey87

Member

Registered: 2021-05-19

Posts: 3

[SOLVED] Error: Specified qdisc not found

I am trying to temporarily add some delay to my existing loopback network interface for testing purposes using:

tc qdisc add dev lo root netem delay 300ms 100ms

Which should as I understand, give me uniformly distributed delays between 200 and 400 milliseconds. However, when I enter this command, I get back the error: "Error: Specified qdisc not found"

Searching on Google, I can see that the solution for those using RHEL is to install a kernel module or set of debugging kernel modules provided by the package kernel-debug-modules-extra. Is there an equivalent package for Arch?

Last edited by allsey87 (2021-05-19 11:47:51)

allsey87

Member

Registered: 2021-05-19

Posts: 3

Re: [SOLVED] Error: Specified qdisc not found

This is the current configuration of the loopback interface:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever

Is it a problem that the current qdisc is "noqueue"?

allsey87

Member

Registered: 2021-05-19

Posts: 3

Re: [SOLVED] Error: Specified qdisc not found

Ok, the problem appears to be that I don't have the kernel module sch_netem available and according to https://samwho.dev/blog/emulating-bad-networks/ and only way to solve this is to build a custom kernel.