From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 22A3133C1 for ; Sat, 4 Nov 2023 09:24:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CC43B8 for ; Sat, 4 Nov 2023 02:24:14 -0700 (PDT) Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-1cc131e52f1so31201635ad.0 for ; Sat, 04 Nov 2023 02:24:14 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699089853; x=1699694653; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:to:from:subject:message-id:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=Cjn2RyeE7N10PxF57KifyI5Qy4viqy4gXk2NkxoPZKw=; b=IPNz0wpwHr4Ba3MFihQVGRzr0PByN6yiZUoroCSLmseWsG7NqAa6JiG0D5TEGa1VEo VMjOSXB0bcBeSjtscAFg2ZP31Hbgn7OCagEO2QtyuFJlR7U9nMCZ2GwziLoNDwssFEuy PYRuj6QQwOFzOx4n9Az0ZPDi8/bOSDBJe6oEl7z184Hm0oLdStHkzitTqJ2Jn/Ns92eB Pma55RYRU3SOTOI39pVKIxHxtOtG/b5fLxZkJb6LXiCYFPNXP8rUNlItbodgwkk/GjLL nnFdhF5l4V1SiBD9M8HuI0K4rLNzhi697fikse6K60liIxfnWJe7mM3SKZudTDzlytBG 8lUQ== X-Gm-Message-State: AOJu0YzPFsaH+tTxwN/FcSPLTD6NwGdT1OYlcg5wySImjmlfgR2sMtbt Znu8wJtoNdl8wHNDCFJSUYHOcY0TVt7IiczV8Mo= X-Google-Smtp-Source: AGHT+IHm5uCTbQEZ0fNlpS+wtOFaFs4bchqd9kWiehP8fJgiUNELNtG9Wd/B56/mhZ2u4bGPfBcu4g== X-Received: by 2002:a17:902:d512:b0:1cc:644a:2129 with SMTP id b18-20020a170902d51200b001cc644a2129mr7100410plg.32.1699089853216; Sat, 04 Nov 2023 02:24:13 -0700 (PDT) Received: from ?IPv6:2001:67c:370:128:83f0:32c0:f09d:82fa? ([2001:67c:370:128:83f0:32c0:f09d:82fa]) by smtp.gmail.com with ESMTPSA id e15-20020a17090301cf00b001b7f40a8959sm2620359plh.76.2023.11.04.02.24.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 04 Nov 2023 02:24:12 -0700 (PDT) Message-ID: <56f87c0304f8e4398d314992d1d872a7772eec9a.camel@inf.elte.hu> Subject: Re: Bypass qdiscs? From: Ferenc Fejes To: John Ousterhout , netdev@vger.kernel.org Date: Sat, 04 Nov 2023 10:24:10 +0100 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.1-1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hi! On Fri, 2023-11-03 at 16:55 -0700, John Ousterhout wrote: > Is there a way to mark an skb (or its socket) before invoking > ip_queue_xmit/ip6_xmit so that the packet will bypass the qdiscs and > be transmitted immediately? Is doing such a thing considered bad > practice? I'm not aware if we have such thing aside from the AF_PACKET's flag=20 PACKET_QDISC_BYPASS [1,2]. I think the function packet_xmit [3] utilizing that flag can be reused for your needs as well. >=20 > (Homa has its own packet scheduling mechanism so the qdiscs are just > getting in the way and adding delays) >=20 > -John- Best, Ferenc [1] https://man7.org/linux/man-pages/man7/packet.7.html [2] https://elixir.bootlin.com/linux/v6.6/source/net/packet/af_packet.c#L4026 [3] https://elixir.bootlin.com/linux/v6.6/source/net/packet/af_packet.c#L273