From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id 2D3B7378E for ; Tue, 27 Oct 2015 02:57:20 +0100 (CET) Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga101.fm.intel.com with ESMTP; 26 Oct 2015 18:57:19 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,202,1444719600"; d="scan'208";a="672350756" Received: from fmsmsx104.amr.corp.intel.com ([10.18.124.202]) by orsmga003.jf.intel.com with ESMTP; 26 Oct 2015 18:57:18 -0700 Received: from fmsmsx117.amr.corp.intel.com (10.18.116.17) by fmsmsx104.amr.corp.intel.com (10.18.124.202) with Microsoft SMTP Server (TLS) id 14.3.248.2; Mon, 26 Oct 2015 18:57:18 -0700 Received: from shsmsx103.ccr.corp.intel.com (10.239.4.69) by fmsmsx117.amr.corp.intel.com (10.18.116.17) with Microsoft SMTP Server (TLS) id 14.3.248.2; Mon, 26 Oct 2015 18:57:18 -0700 Received: from shsmsx101.ccr.corp.intel.com ([169.254.1.96]) by SHSMSX103.ccr.corp.intel.com ([169.254.4.204]) with mapi id 14.03.0248.002; Tue, 27 Oct 2015 09:56:51 +0800 From: "Xie, Huawei" To: Stephen Hemminger Thread-Topic: [dpdk-dev] [PATCH v2 0/5] virtio: Tx performance improvements Thread-Index: AdEMtczKGoGnSN25SBqgZMNDMzsH2Q== Date: Tue, 27 Oct 2015 01:56:51 +0000 Message-ID: References: <1445231772-17467-1-git-send-email-stephen@networkplumber.org> <1536056.KWEakoJpBK@xps13> <20151022090459.68015713@xeon-e3> <20151027085212.24ce7e5e@samsung9> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH v2 0/5] virtio: Tx performance improvements 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: Tue, 27 Oct 2015 01:57:20 -0000 On 10/27/2015 7:52 AM, Stephen Hemminger wrote:=0A= > On Fri, 23 Oct 2015 09:00:38 +0000=0A= > "Xie, Huawei" wrote:=0A= >=0A= >>>> Why use merge-able rx header here in the tx region? =0A= >>> If mergeable rx is negotiated then the header must be used for=0A= >>> both Tx and Rx. I chose to allocate the largest possible header=0A= >>> needed, rather than having to deal with variable size data structure. = =0A= >> Our original code is also using merge-able header for TX descriptor if= =0A= >> this negotiated.=0A= >> I checked the virtio spec, all of the merge-able header is about=0A= >> receiving buffers, which is expected. That is why i feel weird here.=0A= >> Maybe not a big deal?=0A= > Since num_buffers is only in merge-able header, the negotiation is implie= d=0A= > to be symmetric.=0A= >=0A= Can we come to the conclusion that in tx case, we use merge-able header=0A= though number_buffers is not used at all?=0A= > Reading 0.95 spec =0A= >=0A= > Under "Packet Transmission"=0A= > 3. If the driver negotatied the VIRTIO_NET_F_MGR_RXBUF feature=0A= > the num_buffers field is set to zero.=0A= >=0A= >=0A= =0A=