From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Dai, Wei" Subject: Re: [PATCH v2 1/2] net/fm10k: convert to new Rx offloads API Date: Tue, 3 Apr 2018 07:10:45 +0000 Message-ID: <49759EB36A64CF4892C1AFEC9231E8D66CF66147@PGSMSX112.gar.corp.intel.com> References: <20180302141105.4954-1-wei.dai@intel.com> <20180328080037.16207-1-wei.dai@intel.com> <20180328080037.16207-2-wei.dai@intel.com> <039ED4275CED7440929022BC67E706115317576C@SHSMSX103.ccr.corp.intel.com> <039ED4275CED7440929022BC67E7061153175E35@SHSMSX103.ccr.corp.intel.com> <2601191342CEEE43887BDE71AB977258A0AB5BB9@irsmsx105.ger.corp.intel.com> <039ED4275CED7440929022BC67E7061153175FD0@SHSMSX103.ccr.corp.intel.com> <2601191342CEEE43887BDE71AB977258A0AB5C19@irsmsx105.ger.corp.intel.com> <039ED4275CED7440929022BC67E706115317602B@SHSMSX103.ccr.corp.intel.com> <2601191342CEEE43887BDE71AB977258A0AB71B4@irsmsx105.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Cc: "'dev@dpdk.org'" To: "Ananyev, Konstantin" , "Zhang, Qi Z" , "Wang, Xiao W" Return-path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id AD9BD1B643 for ; Tue, 3 Apr 2018 09:12:36 +0200 (CEST) In-Reply-To: <2601191342CEEE43887BDE71AB977258A0AB71B4@irsmsx105.ger.corp.intel.com> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Thanks, Konstantin and Zhang Qi for your feedback and support. I have talked with Qi and know following: To avoid packet dropping when FM10K_SRRCTL_BUFFER_CHAINING_EN is not set, the queue can work with a different mempool which has larger mem buffer siz= e. For example, SCATTER is enabled on queue 0 with a small mem buffer size of = mempool 0, And SCATTER is disabled on queue 1 with a large mem buffer size of mempool = 1, Both queues can avoid packet dropping. Indeed, current fm10k PMD also automatically set FM10K_SRRCTL_BUFFER_CHAINI= NG_EN If max_rx_pkt_len + 2 * VLAN_TAG_SIZE > mem_buf_size no matter whether SCAT= TER is enabled on queue configuration or not. > -----Original Message----- > From: Ananyev, Konstantin > Sent: Sunday, April 1, 2018 8:09 PM > To: Zhang, Qi Z ; Dai, Wei ; > Wang, Xiao W > Cc: 'dev@dpdk.org' > Subject: RE: [dpdk-dev] [PATCH v2 1/2] net/fm10k: convert to new Rx > offloads API >=20 > Hi Qi, >=20 > > > > > > > > > > > > > > Hi Daiwei: > > > > > > > > > > > > > > > +static uint64_t fm10k_get_rx_queue_offloads_capa(struct > > > > > > > > +rte_eth_dev > > > > > > > > +*dev) { > > > > > > > > + RTE_SET_USED(dev); > > > > > > > > + > > > > > > > > + return (uint64_t)(DEV_RX_OFFLOAD_SCATTER); > > > > > > > > +} > > > > > > > > > > > > > > why per queue rx scattered feature here? > > > > > > > My understanding is either we use scattered rx function that > > > > > > > enable this feature for all queues or we use non-scattered > > > > > > > rx function that disable this feature for all queues, right? > > > > > > > > > > > > Checked with Dai Wei offline, fm10k have per queue register > > > > > > that can be configured to support rx scattered, So it is per qu= eue > offload. > > > > > > > > > > Ok, but these days we have one RX function per device. > > > > > Looking at fm10k - it clearly has different RX function for > > > > > scattered and non-scattered case. > > > > > Yes, HW does support scatter/non-scatter selection per queue, > > > > > but our SW - doesn't (same for ixgbe and i40e) So how it could > > > > > be per queue > > > offload? > > > > > > > > We saw the implementation of fm10k is a little bit different with i= 40e. > > > > It set per queue register "FM10K_SRRCTL_BUFFER_CHAINING_EN" to > > > > turn > > > on multi-seg feature when offload is required. > > > > > > > > That means two queues can have different behavior when process a > > > > packet that exceed the buffer size base on the register setting, > > > > though we > > > use the same rx scattered function, so we think this is per queue > > > feature, is that make sense? > > > > > > Ok, suppose we have 2 functions configured. > > > One with DEV_RX_OFFLOAD_SCATTER is on, second with > > > DEV_RX_OFFLOAD_SCATTER is off. > > > So scatter RX function will be selected, but for second queue HW > > > support will not be enabled, so packets bigger then RX buffer will > > > be silently dropped by HW, right? > > > > Yes according to datasheet > > > > Bit FM10K_SRRCTL_BUFFER_CHAINING_EN: > > > > 0b =3D Any packet longer than the data buffer size is terminated with a > > TOO_BIG error status in Rx descriptor write-back. The remainder of the > > frame is not posted to host, it is silently dropped. > > 1b =3D A packet can be spread over more than one single receive data > > buffer > > >=20 > Ok, that's a bit unusual approach but understandable. > Thanks > Konstantin