netdev - Re: [PATCH net-next] tcp: better handle TCP_TX

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Message-ID: <CANn89iLyO66z_r0hfY62dFBuhA-WmYcW+YhuAkDHaShmhUMZwQ@mail.gmail.com>
Date: Tue, 14 Oct 2025 02:40:39 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Simon Horman <horms@...nel.org>, Neal Cardwell <ncardwell@...gle.com>, 
	Willem de Bruijn <willemb@...gle.com>, Kuniyuki Iwashima <kuniyu@...gle.com>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com
Subject: Re: [PATCH net-next] tcp: better handle TCP_TX_DELAY on established flows

On Tue, Oct 14, 2025 at 2:38 AM Paolo Abeni <pabeni@...hat.com> wrote:
>

> What about using a nf rule to drop all the 'tun0' egress packet, instead
> of a qdisc?
>
> In any case I think the pending patches should be ok.

Or add a best effort, so that TCP can have some clue, vast majority of
cases is that the batch is 1 skb :)

diff --git a/net/core/dev.c b/net/core/dev.c
index e281bae9b150..4b938f4d4759 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4226,6 +4226,13 @@ static inline int __dev_xmit_skb(struct sk_buff
*skb, struct Qdisc *q,
                        __qdisc_run(q);
                qdisc_run_end(q);
        } else {
+               if (!llist_next(ll_list)) {
+                       DEBUG_NET_WARN_ON_ONCE(skb != llist_entry(ll_list,
+
struct sk_buff,
+                                                                 ll_node));
+                       rc = dev_qdisc_enqueue(skb, q, &to_free, txq);
+                       ll_list = NULL;
+               }
                llist_for_each_entry_safe(skb, next, ll_list, ll_node) {
                        prefetch(next);
                        skb_mark_not_on_list(skb);