From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 08B1028642B for ; Mon, 10 Nov 2025 16:44:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762793074; cv=none; b=dfXEoQha2UlRTVxQBjE/hCylTn3eeV8L/RXqwIkKH6o0dHzX0L33TO3PqrrHeCG5JQN5q/h1XzUX4BUcM3qChuw2raw9vUt5orylYDthjREv8Q0cLoHVszcdArFukxNWE7wN32/pkKnwPC+Q+siXpsEoAzEW3n4D28wgIDVOAlw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762793074; c=relaxed/simple; bh=H3rg+bLE58X0l5ndlQN9ibafKxCINobeJYzKJIbJkyI=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lNy2Dz8vlBnuco0PZZkaYtGT7l7ZEIsF/tSRIwLC9NSioBcgWaL14mNl7onamny305x2VQCCaObzyZ99AQFiCa8GDWo8LXwUYHFeJ0XrnhklSobJqAac9eHJIv3zdgXVN6FrEtsgZ4wSTV3EbnLMzcxXahs61sKJQ0Aku7/NfdY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HYLUIqPT; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HYLUIqPT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 147F3C4FF58; Mon, 10 Nov 2025 16:44:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762793073; bh=H3rg+bLE58X0l5ndlQN9ibafKxCINobeJYzKJIbJkyI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=HYLUIqPTYatyIh4FxO3vxGMoSs/hiigiMYtRZhMVoSR0hOBcTZAutP8MzhQzi8P4z bejTwi3eeCF5/mpjake+0hX9YVUQ+9oyI2UknoJCbdiTwo/XK8wn/gzX2OTS8pw96j GUIZE7NaEvNyVEpuAxZRcxIt/aI8C38A6vIjgFTas3sNfN5Io7/T9d8b+DxrJeiJXQ LC6e3UUMsj67RlPYILUSwCAH/yd9D/ngxgrYKkj2kv6xlzM+8auZlGIem4CbDJTy/u SITbsKkFYiEVUagcE5gben2kz+Eu48SN9lDmc2VUXfj91sWG5SEkyjcu9Dith1r+F9 UzOI32u3VmDFQ== Date: Mon, 10 Nov 2025 08:44:32 -0800 From: Jakub Kicinski To: Eric Dumazet Cc: "David S . Miller" , Paolo Abeni , Simon Horman , Jamal Hadi Salim , Cong Wang , Jiri Pirko , "Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNlbg==?=" , Kuniyuki Iwashima , Willem de Bruijn , netdev@vger.kernel.org, eric.dumazet@gmail.com Subject: Re: [PATCH net-next 00/10] net_sched: speedup qdisc dequeue Message-ID: <20251110084432.7fdf647b@kernel.org> In-Reply-To: <20251110094505.3335073-1-edumazet@google.com> References: <20251110094505.3335073-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 10 Nov 2025 09:44:55 +0000 Eric Dumazet wrote: > Avoid up to two cache line misses in qdisc dequeue() to fetch > skb_shinfo(skb)->gso_segs/gso_size while qdisc spinlock is held. > > Idea is to cache gso_segs at enqueue time before spinlock is > acquired, in the first skb cache line, where we already > have qdisc_skb_cb(skb)->pkt_len. > > This series gives a 8 % improvement in a TX intensive workload. > > (120 Mpps -> 130 Mpps on a Turin host, IDPF with 32 TX queues) According to CI this breaks a bunch of tests. https://netdev.bots.linux.dev/contest.html?branch=net-next-2025-11-10--12-00 I think they all hit: [ 20.682474][ T231] WARNING: CPU: 3 PID: 231 at ./include/net/sch_generic.h:843 __dev_xmit_skb+0x786/0x1550