From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id AE90B2BA9 for ; Wed, 9 Mar 2016 16:32:08 +0100 (CET) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga103.jf.intel.com with ESMTP; 09 Mar 2016 07:32:07 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,311,1455004800"; d="scan'208";a="933099620" Received: from irsmsx154.ger.corp.intel.com ([163.33.192.96]) by fmsmga002.fm.intel.com with ESMTP; 09 Mar 2016 07:32:06 -0800 Received: from irsmsx111.ger.corp.intel.com (10.108.20.4) by IRSMSX154.ger.corp.intel.com (163.33.192.96) with Microsoft SMTP Server (TLS) id 14.3.248.2; Wed, 9 Mar 2016 15:32:05 +0000 Received: from irsmsx102.ger.corp.intel.com ([169.254.2.19]) by irsmsx111.ger.corp.intel.com ([169.254.2.127]) with mapi id 14.03.0248.002; Wed, 9 Mar 2016 15:32:05 +0000 From: "Kulasek, TomaszX" To: Thomas Monjalon , "Ananyev, Konstantin" Thread-Topic: [dpdk-dev] [PATCH v2 1/2] ethdev: add buffered tx api Thread-Index: AQHRbyZQCQVz9kDF50ioZq1uS6eP859QO/iAgAD3MYCAAA21AIAAEDIAgAAAvwCAAAEBcA== Date: Wed, 9 Mar 2016 15:32:05 +0000 Message-ID: <3042915272161B4EB253DA4D77EB373A14E6A842@IRSMSX102.ger.corp.intel.com> References: <1452869038-9140-1-git-send-email-tomaszx.kulasek@intel.com> <1964417.t7N6HDkJH0@xps13> <2601191342CEEE43887BDE71AB97725836B1A627@irsmsx105.ger.corp.intel.com> <5916803.8PiAMBcxJt@xps13> In-Reply-To: <5916803.8PiAMBcxJt@xps13> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.182] 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 1/2] ethdev: add buffered tx api 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: Wed, 09 Mar 2016 15:32:09 -0000 > -----Original Message----- > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com] > Sent: Wednesday, March 9, 2016 16:27 > To: Ananyev, Konstantin > Cc: Kulasek, TomaszX ; dev@dpdk.org > Subject: Re: [dpdk-dev] [PATCH v2 1/2] ethdev: add buffered tx api >=20 > 2016-03-09 15:23, Ananyev, Konstantin: > > > > > > 2016-03-09 13:36, Ananyev, Konstantin: > > > > > > + if (to_send =3D=3D 0) > > > > > > + return 0; > > > > > > > > > > Why this check is done in the lib? > > > > > What is the performance gain if we are idle? > > > > > It can be done outside if needed. > > > > > > > > Yes, that could be done outside, but if user has to do it anyway, > > > > why not to put it inside? > > > > I don't expect any performance gain/loss because of that - just > > > > seems a bit more convenient to the user. > > > > > > It is handling an idle case so there is no gain obviously. > > > But the condition branching is surely a loss. > > > > I suppose that condition should always be checked: > > either in user code prior to function call or inside the function call > > itself. > > So don't expect any difference in performance here... > > Do you have any particular example when you think it would? > > Or are you talking about rte_eth_tx_buffer() calling > > rte_eth_tx_buffer_flush() internally? > > For that one - both are flush is 'static inline' , so I expect > > compiler be smart enough to remove this redundant check. > > > > > So why the user would you like to do this check? > > Just for user convenience - to save him doing that manually. >=20 > Probably I've missed something. If we remove this check, the function wil= l > do nothing, right? How is it changing the behaviour? If we remove this check, function will try to send 0 packets and check cond= ition for error. So we gain nothing with removing that. Tomasz