From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F3940C433F5 for ; Tue, 8 Mar 2022 13:03:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1oYqsIKkcmataEUtmeD5jZ99oldwbm2YOW3wd8l7PMc=; b=NISDjLUHy2nnrbKez1QX0E8EuL aaJBmFANJ8Wu1ody1FRC9cAR/JG8S9u9+p7uPD7W+y8brCKNnu9OrdsoAV9U+73dj5udQaGcCSPha 7OB0LA5GPCSn3rz/15MnkkybyebSMt7fshmM9k7Tf03Hj+191OskmhAf10HiY0Rb3bd62cue4Z8Sn kXZz0uV60Lx1bzDWrYZefMLuSUSHUzhR2fV9ayKrQGAB7MeS/B+6X85nfE9zJarsUXjFrn//9/mj1 ojn/QVwpLV18drKfdLCFWGBMmQ/o2L2CyhN0JkeF5jtaFsL/70Ke+ftqjYMau+vRxk5gSpDwfxN+3 PYVgk7/Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nRZV1-004Rdl-KU; Tue, 08 Mar 2022 13:03:35 +0000 Received: from smtprz14.163.net ([106.3.154.247] helo=smtp.tom.com) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nRZUx-004Rck-Uy for linux-nvme@lists.infradead.org; Tue, 08 Mar 2022 13:03:34 +0000 Received: from my-app02.tom.com (my-app02.tom.com [127.0.0.1]) by freemail02.tom.com (Postfix) with ESMTP id 624C1B00D3F for ; Tue, 8 Mar 2022 21:03:28 +0800 (CST) Received: from my-app02.tom.com (HELO smtp.tom.com) ([127.0.0.1]) by my-app02 (TOM SMTP Server) with SMTP ID 1055817587 for ; Tue, 08 Mar 2022 21:03:28 +0800 (CST) Received: from antispam1.tom.com (unknown [172.25.16.55]) by freemail02.tom.com (Postfix) with ESMTP id 550BFB00D38 for ; Tue, 8 Mar 2022 21:03:25 +0800 (CST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=tom.com; s=201807; t=1646744608; bh=BwJ+5quvHMWTci0mC33vVMP7HVey1Hn1WFiQ5Ovu7QA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Ll+zPpn2OfUR9p0uvKDlDba2wHKrzE102C+jM+zxPCrbwwRORZ4pdhScfcoJGjQH/ tMRaSliXE54mLy12+GFyLES0yWt971/YGvxE0L7J+cJ6zK5+l3as+GiX8GAAhbKwe0 2shDzft0YDAXIcinDyPLVCNJ7QT0KCw0dS4Q9rZs= Received: from antispam1.tom.com (antispam1.tom.com [127.0.0.1]) by antispam1.tom.com (Postfix) with ESMTP id 52E47D415B2 for ; Tue, 8 Mar 2022 21:03:25 +0800 (CST) X-Virus-Scanned: Debian amavisd-new at antispam1.tom.com Received: from antispam1.tom.com ([127.0.0.1]) by antispam1.tom.com (antispam1.tom.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dmii8XDxoK2Y for ; Tue, 8 Mar 2022 21:03:24 +0800 (CST) Received: from localhost (unknown [101.93.196.13]) by antispam1.tom.com (Postfix) with ESMTPA id 77F9DD41599; Tue, 8 Mar 2022 21:03:21 +0800 (CST) Date: Tue, 8 Mar 2022 21:03:20 +0800 From: Mingbao Sun To: Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Cc: tyler.sun@dell.com, ping.gan@dell.com, yanxiu.cai@dell.com, libin.zhang@dell.com, ao.sun@dell.com Subject: Re: [PATCH 0/2] NVMe_over_TCP: support specifying the congestion-control Message-ID: <20220308210320.000013ca@tom.com> In-Reply-To: <20220304092754.2721-1-sunmingbao@tom.com> References: <20220304092754.2721-1-sunmingbao@tom.com> X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220308_050332_370797_49EEB7A9 X-CRM114-Status: UNSURE ( 9.28 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org I feel that I'd better address this a little bit more to express the meaning behind this feature. You know, InfiniBand/RoCE provides NVMe-oF a lossless network environment (that is zero packet loss), which is a great advantage to performance. In contrast, 'TCP/IP + ethernet' is often used as a lossy network environment (packet dropping often occurs).=20 And once packet dropping occurs, timeout-retransmission would be triggered. But once timeout-retransmission was triggered, it=E2=80=99s a gr= eat damage to the performance. So although NVMe/TCP may have a bandwidth competitive to that of NVMe/RDMA, but the packet dropping of the former is a flaw to its performance. However, with the combination of the following conditions, NVMe/TCP can almost be as competitive as NVMe/RDMA in the data center. - Ethernet NICs supporting QoS configuration (support mapping TOS/DSCP in IP header into priority, support PFC) - Ethernet Switches supporting ECN marking, supporting adjusting buffer size of each priority. - NVMe/TCP supports specifying the tos for its TCP traffic (already implemented) - NVMe/TCP supports specifying dctcp as the congestion-control of its TCP sockets (the work of this feature) So this feature is the last item from the software aspect to form up the above combination.