From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f48.google.com (mail-wm0-f48.google.com [74.125.82.48]) by dpdk.org (Postfix) with ESMTP id 746222A5E for ; Tue, 8 Dec 2015 00:55:27 +0100 (CET) Received: by wmec201 with SMTP id c201so189509003wme.0 for ; Mon, 07 Dec 2015 15:55:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:organization:user-agent :in-reply-to:references:mime-version:content-transfer-encoding :content-type; bh=wq2fau8eQoNUveGeRNERmJ0hVtxbdIeB4Ko+9a6HsBI=; b=uenn86W3NCfSZhCEsNtTeGGiJaSJGGfG8j2FPe8QfYHAyAgIR/6uQ78TcaP8KvRJCg rp1yCsVe5X3ebmm9IFC81HwtIgT048WpSg1agU9eORa2E4JkeAbQc/gu+R2pZcV1o4e7 nLQKNVlxxwc/DdwadsD2BuBbj+jawailowZ/OwuIeQeu5CM1YecTUfGHzlPtcRoexhPO 2QsYyT4pkEICdCHIEBi3AJnuOVdGxnkNnU5DpWK/ShojVBsqTgdGWriQVGpXRHwiIBvG lGQM6d//4NN2TxdxzxbFsrTPu/8XorPJNzhLSCIkhFcstRy4elXA4Nu0wq1BlErPBT1A GsJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:organization :user-agent:in-reply-to:references:mime-version :content-transfer-encoding:content-type; bh=wq2fau8eQoNUveGeRNERmJ0hVtxbdIeB4Ko+9a6HsBI=; b=BAz3sKUyEq8XhO6Dicg4z8d55y1m5zJc3RdsTQaeh70UeGHCiC9B4L9REEXxIN1fBv fra9BVav8L4uBrOsTXn1VqOWUeG8ozN8SccaVHPBfuca5nAfvjLNUY+KOwWrzO6oVcTn LrYCwXFJ/jO1WhewyFpGzsTOgCJPARozyTAlzNv0KxY9pNT9VEnZnpug6kKR3phR/tmu L1bXekPAba+R5J692Tqz7BJIAyIM4qbk21mk9WW7XIZYP9ogZOngX6Aof1WiRLCn/tLa DWjRoqh5ndXUBmPq9wzCUilG2YxftYXyKBPME8lBh4VswmoViSpfP1vJpx47XmyWfQE8 nlAg== X-Gm-Message-State: ALoCoQkyeGBZSwihd39YKpe2q1UA/wc+wv3sf5pS8jy6EQaGAdQ1mkRwIoD7FMAy8QYhTfE1lc4ok6t+xVd8FXEheDZLorioEA== X-Received: by 10.194.243.6 with SMTP id wu6mr448158wjc.14.1449532527357; Mon, 07 Dec 2015 15:55:27 -0800 (PST) Received: from xps13.localnet (136-92-190-109.dsl.ovh.fr. [109.190.92.136]) by smtp.gmail.com with ESMTPSA id h5sm391370wjz.21.2015.12.07.15.55.26 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 07 Dec 2015 15:55:26 -0800 (PST) From: Thomas Monjalon To: Yuanhan Liu Date: Tue, 08 Dec 2015 00:54:15 +0100 Message-ID: <2034837.2nzjXYH9Th@xps13> Organization: 6WIND User-Agent: KMail/4.14.10 (Linux/4.1.6-1-ARCH; KDE/4.14.11; x86_64; ; ) In-Reply-To: <1449109622-11675-1-git-send-email-yuanhan.liu@linux.intel.com> References: <1449109622-11675-1-git-send-email-yuanhan.liu@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Cc: dev@dpdk.org, Victor Kaplansky , "Michael S. Tsirkin" Subject: Re: [dpdk-dev] [PATCH] vhost: reserve some spaces for virtio_net and vhost_virtqueue struct X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Dec 2015 23:55:27 -0000 2015-12-03 10:27, Yuanhan Liu: > So that we will not break ABI in future extension by adding few more > fields. > > Struct vhost_virtqueue is reserved with 16 qwords (the later vhost-live > migration support would at least consume 3 of them), and struct virtio_net > is reserved with a bit more, 64 qwords, as there is only one instance for > a virtio nic instance. > > Note that both reservation are not placed at the end of the struct, but > instead before the last field, since both the last field at the two struct > take a lot spaces. Putting the reservation after it would divide those > reserved fields to another cacheline. (we might need fix them in future, btw) > > CC: Panu Matilainen > CC: Thomas Monjalon > CC: Michael S. Tsirkin > CC: Victor Kaplansky > Suggested-by: Panu Matilainen > Signed-off-by: Yuanhan Liu > --- > > Is the reservation a bit too large? :) You are maintainer in this area. Applied, thanks