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Date: Mon, 9 Mar 2026 18:58:43 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann
 <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, "David S .
 Miller" <davem@davemloft.net>, Paolo Abeni <pabeni@redhat.com>,
 netdev@vger.kernel.org, bpf@vger.kernel.org, Simon Horman
 <horms@kernel.org>, Jamal Hadi Salim <jhs@mojatatu.com>, Victor Nogueira
 <victor@mojatatu.com>, Cong Wang <xiyou.wangcong@gmail.com>, Jiri Pirko
 <jiri@resnulli.us>, "Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNlbg==?="
 <toke@redhat.com>, eric.dumazet@gmail.com, Yunsheng Lin
 <linyunsheng@huawei.com>
Subject: Re: [PATCH v2 net-next] net/sched: do not reset queues in graft
 operations
Message-ID: <20260309185843.50ce9259@kernel.org>
In-Reply-To: <20260307163430.470644-1-edumazet@google.com>
References: <20260307163430.470644-1-edumazet@google.com>
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On Sat,  7 Mar 2026 16:34:30 +0000 Eric Dumazet wrote:
> I think the problem (quadratic behavior) was added in commit
> 2fb541c862c9 ("net: sch_generic: aviod concurrent reset and enqueue op
> for lockless qdisc") but this does not look serious enough to deserve
> risky backports.

FWIW I was wondering whether with your recent llist in place we could
retire the NOLOCK concept. So many workarounds grew around it at
this point :( But in a naive pktgen+dummy test llist ends up dropping
most packets. Not sure what it looks like on a more realistic setup.