From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx-3.enea.com (sestofw01.enea.se [192.36.1.252]) by dpdk.org (Postfix) with SMTP id CF90FC388 for ; Thu, 23 Jul 2015 17:20:04 +0200 (CEST) Received: from [192.168.15.79] (192.168.15.79) by smtp.enea.com (172.21.1.209) with Microsoft SMTP Server id 14.3.224.2; Thu, 23 Jul 2015 17:20:03 +0200 Message-ID: <55B10619.1060801@enea.com> Date: Thu, 23 Jul 2015 18:19:53 +0300 From: ciprian.barbu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: References: <55A90790.1030700@enea.com> In-Reply-To: <55A90790.1030700@enea.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.15.79] Subject: Re: [dpdk-dev] can eth_igb_xmit_pkts called with len 0 affect transmission? 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: Thu, 23 Jul 2015 15:20:05 -0000 Anyone? On 17.07.2015 16:48, ciprian.barbu wrote: > Hi, > > I'm seeing a strange behavior when calling rte_eth_tx_burst with len == > 0. I'll explain the reason for this situation further bellow. But what > I'm seeing is that after doing this call my application keeps returning > from eth_igb_xmit_pkts here, even when len > 0: > http://dpdk.org/browse/dpdk/tree/lib/librte_pmd_e1000/igb_rxtx.c?h=releases#n476 > > > I can't really explain myself this behavior, I don't understand very > well what the nic does once it receives buffers in its rings, but to me > it looks like calling rte_eth_tx_burst with len 0 has this effect. > > What I'm using in my tests is the linaro odp-dpdk implementation and the > odp_l2fwd example. The odp-dpdk implementation makes this call to try > and make the pmd to flush the tx queue in case there are no more free > buffers in the pool, but this was only verified for ixgbe 82599 cards, > for igb the packets are not actually flushed until the tail circles back > the whole length of the queue. I'm pretty much the only one (that I know > of) that uses odp with 1G igb i350 cards and see this issue. > > Can anyone explain whether I'm getting this right and there could be > side effects to calling eth_igb_xmit_pkts with len 0? > > Thank you, > /Ciprian