From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f51.google.com (mail-wm0-f51.google.com [74.125.82.51]) by dpdk.org (Postfix) with ESMTP id A3EA32E81 for ; Wed, 9 Mar 2016 17:03:47 +0100 (CET) Received: by mail-wm0-f51.google.com with SMTP id l68so199423593wml.0 for ; Wed, 09 Mar 2016 08:03:47 -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; bh=f2Sqk3jM/iEgFaC/ULJnV0e5unZRJrdRFAuhzKZBjBw=; b=m6PVPFuJmbbrF9u6bcI4f8xm2WoVTeAF1m0BlvAj/HJrR2mqSx2R2qccFnYlfqpNLE XY8J9tDhzXkBDZgmVTs7z/+L8ndWPPAiP3MFICuJPp6XqvNjjUkWxL+/qy0mpieym9dx flV+Ii659ZItKr4jVg41HQP9aYPSIuAjntf0bdVkLJmapH749Sz7dTDvyjycA/PX0RVn nY9nvRgTzjtA3HT658g+9uTf4fHqEUYIDW5UoyJFdR7mc40d+U51upFlG0etW3w4Ya6p fEYRqDoUkFP4UtR6g2zmEpggrgp4Ce5eLGSTNe6vc+4Hg7F/w2Xxqhk6AnfHTYcd+yLm TYfA== 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; bh=f2Sqk3jM/iEgFaC/ULJnV0e5unZRJrdRFAuhzKZBjBw=; b=V7ahf94MIT9rPJ3WXNbKG77XRbB0mhl/K/R5ZP55zOVbmbxhcVfi869qcXWUYM7ExX YCLcXk1q1MrBbiUUXFYMvqU8dEUhgVrMY2bYo7b9Q6KnJaSPgmiK37La2HTxfcFftvBM eCBtn6lyraWRL8NDFAP7k0lVGFSYTE+tNgrU1+CdlZrgeQGwYxncjJl9APi6VAJ1vw46 cVrhBYFFB4CzMgTwQsEhHc5A8sNP5gDTQCaFa3O86l97MoniqCuoGbpHSS6eLD9hxU7W l2Ym+4sZ//BM1W6rkVXfflKwRWfbDZSeIeHbO+w86D/5oCuro8zJItnuAVc4oJ4oqMsR bmWA== X-Gm-Message-State: AD7BkJLD+JmFvIgK9ZigSahcc8Pb+D4z9/cuNon0/qPhNEwsD1YRbj5duq7fAwBl2lTwPlXK X-Received: by 10.28.136.19 with SMTP id k19mr25137265wmd.11.1457539427263; Wed, 09 Mar 2016 08:03:47 -0800 (PST) Received: from xps13.localnet (91.111.75.86.rev.sfr.net. [86.75.111.91]) by smtp.gmail.com with ESMTPSA id k124sm8937965wmb.11.2016.03.09.08.03.46 (version=TLSv1/SSLv3 cipher=OTHER); Wed, 09 Mar 2016 08:03:46 -0800 (PST) From: Thomas Monjalon To: "Kulasek, TomaszX" Date: Wed, 09 Mar 2016 16:37:21 +0100 Message-ID: <7687094.ndhEsKzoZH@xps13> Organization: 6WIND User-Agent: KMail/4.14.10 (Linux/4.1.6-1-ARCH; KDE/4.14.11; x86_64; ; ) In-Reply-To: <3042915272161B4EB253DA4D77EB373A14E6A842@IRSMSX102.ger.corp.intel.com> References: <1452869038-9140-1-git-send-email-tomaszx.kulasek@intel.com> <5916803.8PiAMBcxJt@xps13> <3042915272161B4EB253DA4D77EB373A14E6A842@IRSMSX102.ger.corp.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" 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 16:03:47 -0000 2016-03-09 15:32, Kulasek, TomaszX: > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com] > > 2016-03-09 15:23, Ananyev, Konstantin: > > > > > > > > 2016-03-09 13:36, Ananyev, Konstantin: > > > > > > > + if (to_send == 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. > > > > Probably I've missed something. If we remove this check, the function will > > do nothing, right? How is it changing the behaviour? > > If we remove this check, function will try to send 0 packets and check > condition for error. So we gain nothing with removing that. Actually I should not arguing why removing it, but you should arguing why adding it :)