From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5756C3A4F50 for ; Mon, 9 Mar 2026 11:44:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773056658; cv=none; b=Hx7G+DBCLQsroEH0AR7kAAlxEY0L8oTcBQGtDQFeCiq27kcVQse0Yb/FsnkSrO8NCBucQHNKdLbOSOnkBp6ddoHx+xpX3n3pL1FV2TFyVejciwKc8uQR2Jq96IqDWhlDIqgCqzletFoABFyL5Wo0DHYvlKsSr8iMam6D72XquZ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773056658; c=relaxed/simple; bh=bNDsGMnQx71dEQWIFI4yiXH735wX4TuPuBfM6VuqrfI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=te93FOVcwcguh9Ni6rpGNkOqSFKnsA6EjT0nM8mFM7dAnPXyga28o4AitHqDSmLMWrQG+lrbbEq0J8jUoSO3TVwqJLin53EL0gMVyKZG2+LkqvDPO2gJd5pDSkLBVtjdvGZZOL3NkKvagCaAwTVHrM7M51BFdMNjgLnttFjCCmk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=C6DocFnV; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=lccRjXH3; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="C6DocFnV"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="lccRjXH3" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773056656; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=A3bg7TH0WlNH+XsmNxKjZXpIrTM8y8yXJ1xiD9A5bt0=; b=C6DocFnVjuqqSC7ptkxw6uHsprTrNdljvVi2zEBti0df/y2gT5iLimCBrq2er1ksk7JkyP MLezfCAgxiUGNmkTR6E+fhOAsJ8HT2/5tzkeU5kbvAQB5U/5lDv24uED4BuuzmpdMkoihT qihDvLT8djCxiHenLHMzm2QvwfMXNlI= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-581-2pt9guQaNJye_erilxQiWw-1; Mon, 09 Mar 2026 07:44:14 -0400 X-MC-Unique: 2pt9guQaNJye_erilxQiWw-1 X-Mimecast-MFC-AGG-ID: 2pt9guQaNJye_erilxQiWw_1773056653 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-439cbc5fd75so3927220f8f.0 for ; Mon, 09 Mar 2026 04:44:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1773056653; x=1773661453; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:references :in-reply-to:subject:cc:to:from:from:to:cc:subject:date:message-id :reply-to; bh=A3bg7TH0WlNH+XsmNxKjZXpIrTM8y8yXJ1xiD9A5bt0=; b=lccRjXH3TV5q7d/Q5hMzIENBPUg8VxtaLppwRsgbnh2X/Z5Cd5qzErPPUgwdeybyeM /fiv34zanvlHj4mzgj6YmCjqX7e1QRt49UcmphTAxj2M+ayEO9XyE5Gv7Ql8S57VWOGq WtGEjnPmOzBMp/etNJjhiL3gzhu7CobzkQlQkxTyaEg4891c7VSOcGMR4f5fvnInqrtX qmu6bzapGersDfitENoPqf1AtOgPs/YCg0iea6pJTDNdt2FYKkRDNTMm+XSGEmYtzvJZ ahvRt2ygnibZnzbSWASyRULHgK9nCVR5lEJFL/kYxbgA6rR9tpifDQQM0HU3th6XgWQ3 oRnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773056653; x=1773661453; h=content-transfer-encoding:mime-version:message-id:date:references :in-reply-to:subject:cc:to:from:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=A3bg7TH0WlNH+XsmNxKjZXpIrTM8y8yXJ1xiD9A5bt0=; b=TYO4whJch/qBBivECk0BXEMEu8BGVL6nqTW+ho8xJ13WZ6FY4KjTASaBAKtG45YTvd UVN7VAGotnhvVIrghK+7iGq7rtPq+50yV11gJkOm8mdqWqLqIG6qE4cMabpKc1GTFX6a +Lh4/A0uAPf09rA/JSCSSZMMfna1Sxt5C8QIPj3Th/YvDQwBaBxmIWmp6z4csK1/0Nr8 33M8jyp2XPhpagffSHySFv1NKtlo0w7TO1mjEJy7fFHoM06z8aQAiPdvFA4lTrppIYLs ub1Z/4/fvsQgdFdu9wQWezxgKnKJUviwMLqjGGuQrl8QPT8chTsjOIgJqJO1OC27dD+I 2Ixw== X-Gm-Message-State: AOJu0Yxe6PAuNOB3jbJl6znMmyo/MGmOno0KgeMQqQVOpZHkLDbRMilz zZ8oN8AeCo8TXmnO2hV36rh0IRa/IL/4i9Uas7zwiPphc+cjVyUFB5rC9iqGeV1keCcsJpXwyLr rygnWjYx8glCgbSeXfemv8o7Lk74WAeMX3O9xrNImgEnvyNVQMYHJm0Jr8g== X-Gm-Gg: ATEYQzyBajmS8tansxjgvy7jdT5g85G6d3ro+VGSG5yO0UvhDLfDQmKnrrajOU7Skfk E/IJ+1e5s/MySEPy4Y6VMDKWUzV2BJtnKMTc6g06G/tewtvvj5IFlV0wvc1n4R4dFPpVyOdqe8l HNZrio29KuoQUlD+j5OIrGW966HpaBDNV3/vpDo4Db5zIrQ4ijagONVy3q0xwCBY37z1Lgg5S6Y /vEb2Nq69QXBxtliK46AUx3zlyyEPchy66aa0IaeFHUtbagX5tjEBXM2IkgTLVY2hhPQOrUMOCd 4He3Qfqb97ijQFrwyfHS+6Xvo2xoR56BK1/aw3egablW95xaJHHdqBl0kTcBP9l1oQc5E/uBtEW RfmwTY2v3+3aj7VRCH72WYYp1DURqrrAe9m4v66gNoat3bZN9 X-Received: by 2002:a05:600c:8712:b0:485:2ce2:4c75 with SMTP id 5b1f17b1804b1-4852ce24f8cmr151212935e9.1.1773056653008; Mon, 09 Mar 2026 04:44:13 -0700 (PDT) X-Received: by 2002:a05:600c:8712:b0:485:2ce2:4c75 with SMTP id 5b1f17b1804b1-4852ce24f8cmr151212305e9.1.1773056652400; Mon, 09 Mar 2026 04:44:12 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk (alrua-x1.borgediget.toke.dk. [2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-485246ff886sm87283795e9.24.2026.03.09.04.44.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2026 04:44:11 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 0A86F5A1D3A; Mon, 09 Mar 2026 12:44:10 +0100 (CET) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Eric Dumazet , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Simon Horman , Jamal Hadi Salim , Victor Nogueira , Cong Wang , Jiri Pirko , eric.dumazet@gmail.com, Eric Dumazet , Yunsheng Lin Subject: Re: [PATCH v2 net-next] net/sched: do not reset queues in graft operations In-Reply-To: <20260307163430.470644-1-edumazet@google.com> References: <20260307163430.470644-1-edumazet@google.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Mon, 09 Mar 2026 12:44:09 +0100 Message-ID: <87qzptp6ra.fsf@toke.dk> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Eric Dumazet writes: > Following typical script is extremely disruptive, > because each graft operation calls dev_deactivate() > which resets all the queues of the device. > > QPARAM=3D"limit 100000 flow_limit 1000 buckets 4096" > TXQS=3D64 > for ETH in eth1 > do > tc qd del dev $ETH root 2>/dev/null > tc qd add dev $ETH root handle 1: mq > for i in `seq 1 $TXQS` > do > slot=3D$( printf %x $(( i )) ) > tc qd add dev $ETH parent 1:$slot fq $QPARAM > done > done > > One can add "ip link set dev $ETH down/up" to reduce the disruption time: > > QPARAM=3D"limit 100000 flow_limit 1000 buckets 4096" > TXQS=3D64 > for ETH in eth1 > do > ip link set dev $ETH down > tc qd del dev $ETH root 2>/dev/null > tc qd add dev $ETH root handle 1: mq > for i in `seq 1 $TXQS` > do > slot=3D$( printf %x $(( i )) ) > tc qd add dev $ETH parent 1:$slot fq $QPARAM > done > ip link set dev $ETH up > done > > Or we can add a @reset_needed flag to dev_deactivate() and > dev_deactivate_many(). > > This flag is set to true at device dismantle or linkwatch_do_dev(), > and to false for graft operations. > > In the future, we might only stop one queue instead of the whole > device, ie call dev_deactivate_queue() instead of dev_deactivate(). > > 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. > > Signed-off-by: Eric Dumazet > Cc: Yunsheng Lin Reviewed-by: Toke H=C3=B8iland-J=C3=B8rgensen