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 X-Spam-Level: X-Spam-Status: No, score=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E7C2C433ED for ; Fri, 9 Apr 2021 13:39:08 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 26F08610E5 for ; Fri, 9 Apr 2021 13:39:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 26F08610E5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37012 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lUrLn-0002El-4Q for qemu-devel@archiver.kernel.org; Fri, 09 Apr 2021 09:39:07 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37502) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lUnjX-0002Bm-BF for qemu-devel@nongnu.org; Fri, 09 Apr 2021 05:47:23 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30375) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lUnjV-0000DV-KA for qemu-devel@nongnu.org; Fri, 09 Apr 2021 05:47:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617961641; 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=VPnUnKvL6Mz5cjC38j3F81fcTez/Pf/1S0BlNPmJrwc=; b=L3DZI2Pn0AvP6GlTiIXfZjK/4wUetQfW3Ybtgnob2s+t8wuKr0jH6f2OWMtPaEUbgV9Khm rA+cs4eTK0C4dyBUeP2vmDoxiwuzkj8QvvF4GhcKtMY78MtFR+WmJjYQuXl7ETx7ZVa2tv Bxwhy5BneKFO6MRTpzuaJ+0LzGDFR4Y= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-57--3kqUT1_MWua5INP0r_n1Q-1; Fri, 09 Apr 2021 05:47:19 -0400 X-MC-Unique: -3kqUT1_MWua5INP0r_n1Q-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 37DEE83DD20 for ; Fri, 9 Apr 2021 09:47:18 +0000 (UTC) Received: from ovpn-115-50.ams2.redhat.com (ovpn-115-50.ams2.redhat.com [10.36.115.50]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2F18D5D9C0; Fri, 9 Apr 2021 09:47:12 +0000 (UTC) Message-ID: Subject: Re: [RFC PATCH 0/5] mptcp support From: Paolo Abeni To: "Daniel P." =?ISO-8859-1?Q?Berrang=E9?= , "Dr. David Alan Gilbert (git)" Date: Fri, 09 Apr 2021 11:47:11 +0200 In-Reply-To: References: <20210408191159.133644-1-dgilbert@redhat.com> User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pabeni@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=pabeni@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Fri, 09 Apr 2021 09:37:50 -0400 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: armbru@redhat.com, quintela@redhat.com, qemu-devel@nongnu.org, kraxel@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, 2021-04-09 at 10:34 +0100, Daniel P. Berrangé wrote: > On Thu, Apr 08, 2021 at 08:11:54PM +0100, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > Hi, > > This RFC set adds support for multipath TCP (mptcp), > > in particular on the migration path - but should be extensible > > to other users. > > > > Multipath-tcp is a bit like bonding, but at L3; you can use > > it to handle failure, but can also use it to split traffic across > > multiple interfaces. > > > > Using a pair of 10Gb interfaces, I've managed to get 19Gbps > > (with the only tuning being using huge pages and turning the MTU up). > > > > It needs a bleeding-edge Linux kernel (in some older ones you get > > false accept messages for the subflows), and a C lib that has the > > constants defined (as current glibc does). > > > > To use it you just need to append ,mptcp to an address; > > > > -incoming tcp:0:4444,mptcp > > migrate -d tcp:192.168.11.20:4444,mptcp > > What happens if you only enable mptcp flag on one side of the > stream (whether client or server), does it degrade to boring > old single path TCP, or does it result in an error ? If the mptcp handshake fails by any means - e.g. one side does not ask for MPTCP - the connection fallbacks to plain TCP in a transparent way. > > I had a quick go at trying NBD as well, but I think it needs > > some work with the parsing of NBD addresses. > > In theory this is applicable to anywhere that we use sockets. > Anywhere that is configured with the QAPI SocketAddress / > SocketAddressLegacy type will get it for free AFAICT. > > Anywhere that is configured via QemuOpts will need an enhancement. > > IOW, I would think NBD already works if you configure NBD via > QMP with nbd-server-start, or block-export-add. qemu-nbd will > need cli options added. > > The block layer clients for NBD, Gluster, Sheepdog and SSH also > all get it for free when configured va QMP, or -blockdev AFAICT > > Legacy blocklayer filename syntax would need extra parsing, or > we can just not bother and say if you want new features, use > blockdev. > > > Overall this is impressively simple. > > It feels like it obsoletes the multifd migration code, at least > if you assume Linux platform and new enough kernel ? > > Except TLS... We already bottleneck on TLS encryption with > a single FD, since userspace encryption is limited to a > single thread. > > There is the KTLS feature which offloads TLS encryption/decryption > to the kernel. This benefits even regular single FD performance, > because the encrytion work can be done by the kernel in a separate > thread from the userspace IO syscalls. > > Any idea if KTLS is fully compatible with MPTCP ? Ouch! So far is not supported. Both KTLS and MPTCP use/need ULP (Upper Layer Protocol, a kernel way of hijaking core TCP features) and we can have a single ULP per socket, so possibly that there is some technical show- stopper there. At very least is not in our short term roadmap, but I guess we can updated that based on user needs. Thanks! Paolo