linux-kernel - Re: [Bug 220774] New: netem is broken in 6.18

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Message-ID: <20251121161322.1eb61823@phoenix.local>
Date: Fri, 21 Nov 2025 16:13:22 -0800
From: Stephen Hemminger <stephen@...workplumber.org>
To: Cong Wang <xiyou.wangcong@...il.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>, netdev@...r.kernel.org,
 kuba@...nel.org, linux-kernel@...r.kernel.org, will@...lsroot.io,
 jschung2@...ton.me, savy@...t3mfailure.io
Subject: Re: [Bug 220774] New: netem is broken in 6.18

On Fri, 21 Nov 2025 13:45:06 -0800
Cong Wang <xiyou.wangcong@...il.com> wrote:

> On Fri, Nov 21, 2025 at 07:52:37AM -0500, Jamal Hadi Salim wrote:
>  
> > jschung2@...ton.me: Can you please provide more details about what you
> > are trying to do so we can see if a different approach can be
> > prescribed?
> >   
> 
> An alternative approach is to use eBPF qdisc to replace netem, but:
> 1) I am not sure if we could duplicate and re-inject a packet in eBPF Qdisc
> 2) I doubt everyone wants to write eBPF code when they already have a
> working cmdline.
> 
> BTW, Jamal, if your plan is to solve them one by one, even if it could work,
> it wouldn't scale. There are still many users don't get hit by this
> regression yet (not until hitting LTS or major distro).
> 
> Regards,
> Cong

The bug still needs to be fixed.
eBPF would still have the same kind of issues.