Subject: Re: [Patch net v6 4/8] net_sched: Implement the right netem duplication behavior

From: Jakub Kicinski <[email-masked]>
Date: Sun, 4 Jan 2026 11:19:12 -0800

On Tue, 30 Dec 2025 09:28:50 -0800 Stephen Hemminger wrote:
> It is worth testing for the case where netem is used as a leaf qdisc.
> I worry that this could cause the parent qdisc to get accounting wrong.
> I.e if HTB calls netem and netem queues 2 packets, the qlen in HTB
> would be incorrect.

Indeed, presumably backlog should be corrected with
qdisc_tree_reduce_backlog() ? Either way it'd be great to add / adjust 
some test cases to confirm backlogs are 0 after the traffic stopped.