From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 5C56BA0548; Tue, 20 Apr 2021 14:44:18 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id D592641749; Tue, 20 Apr 2021 14:44:17 +0200 (CEST) Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) by mails.dpdk.org (Postfix) with ESMTP id 8513D41735 for ; Tue, 20 Apr 2021 14:44:15 +0200 (CEST) Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4FPjwV2HZJzpZW8; Tue, 20 Apr 2021 20:41:14 +0800 (CST) Received: from [127.0.0.1] (10.69.27.114) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.498.0; Tue, 20 Apr 2021 20:44:06 +0800 To: "Ananyev, Konstantin" , "Yigit, Ferruh" , "dev@dpdk.org" References: <1618571071-5927-1-git-send-email-tangchengchang@huawei.com> <58a7abc3-0906-57f2-5fd3-7e875b6f4c1e@intel.com> CC: "linuxarm@huawei.com" , "chas3@att.com" , "humin29@huawei.com" From: Chengchang Tang Message-ID: <04b8a7cd-2563-a7a1-e30a-915da5b2bca3@huawei.com> Date: Tue, 20 Apr 2021 20:44:06 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.69.27.114] X-CFilter-Loop: Reflected Subject: Re: [dpdk-dev] [RFC 0/2] add Tx prepare support for bonding device X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi On 2021/4/20 16:33, Ananyev, Konstantin wrote: > Hi everyone, > >> >> On 2021/4/20 9:26, Ferruh Yigit wrote: >>> On 4/16/2021 12:04 PM, Chengchang Tang wrote: >>>> This patch add Tx prepare for bonding device. >>>> >>>> Currently, the bonding driver has not implemented the callback of >>>> rte_eth_tx_prepare function. Therefore, the TX prepare function of the >>>> slave devices will never be invoked. When hardware offloading such as >>>> CKSUM and TSO are enabled for some drivers, tx_prepare needs to be used >>>> to adjust packets (for example, set correct pseudo packet headers). >>>> Otherwise, related offloading fails and even packets are sent >>>> incorrectly. Due to this limitation, the bonded device cannot use these >>>> HW offloading in the Tx direction. >>>> >>>> Because packet sending algorithms are numerous and complex in bond PMD, >>>> it is hard to design the callback for rte_eth_tx_prepare. In this patch, >>>> the tx_prepare callback of bonding PMD is not implemented. Instead, >>>> rte_eth_tx_prepare has been called in tx_burst callback. And a global >>>> variable is introduced to control whether the bonded device need call >>>> the rte_eth_tx_prepare. If upper-layer users need to use some TX >>>> offloading that depend on tx_prepare , they should enable the preparation >>>> function. In this way, the bonded device will call the rte_eth_tx_prepare >>>> for the fast path packets in the tx_burst callback. > > I admit that I didn't look at the implementation yet, but it sounds like > overcomplication to me. Can't we just have a new TX function for bonding PMD > when TX offloads are enabled? And inside that function we will do: > tx_prepare(); tx_burst(); for selected device. The solution you mentioned is workable and may perform better. However, the current solution is also simple and has a limited impact on performance. It is actually: if (tx_prepare_enable) tx_prepare(); tx_burst(); Overall, it adds almost only one judgment to the case where the related Tx offloads is not turned on. > We can select this function at setup stage analysing requested by user TX offloads. > In PMDs, it is a common practice to select different Tx/Rx function during the setup phase. But for a 'vdev' device like Bonding, we may need to think more about it. The reasons are explained below. > >>>> >>> >>> What do you think to add a devarg to bonding PMD to control the tx_prepare? >>> It won't be as dynamic as API, since it can be possible to change the behavior after application is started with API, but do we really need >> this? >> >> If an API is not added, unnecessary constraints may be introduced. If the >> bonding device is created through the rte_eth_bond_create interface instead >> devarg "vdev", this function cannot be used because devargs does not take effect >> in this case. But from an ease-of-use perspective, adding a devarg is a good >> idea. I will add related implementations in the later official patches. > > I am also against introducing new devarg to control tx_prepare() invocation. > I think at dev_config/queue_setup phase PMD will have enough information to decide. > Currently, the community does not specify which Tx offloads need to invoke tx_prepare. For Vdev devices such as bond, all NIC devices need to be considered. Generally, tx_prepare is used in CKSUM and TSO. It is possible that for some NIC devices, even CKSUM and TSO do not need to invoke tx_prepare, or for some NIC devices, there are other Tx offloads that need to call tx_prepare. From this perspective, leaving the choice to the user seems to be a better choice. >> >> If I understand correctly, the current community does not want to introduce >> more private APIs for PMDs. However, the absence of an API on this issue would >> introduce some unnecessary constraints, and from that point of view, I think >> adding an API seems necessary. >>> >>>> Chengchang Tang (2): >>>> net/bonding: add Tx prepare for bonding >>>> app/testpmd: add cmd for bonding Tx prepare >>>> >>>> app/test-pmd/cmdline.c | 66 +++++++++++++++++++++++++++++ >>>> doc/guides/testpmd_app_ug/testpmd_funcs.rst | 9 ++++ >>>> drivers/net/bonding/eth_bond_private.h | 1 + >>>> drivers/net/bonding/rte_eth_bond.h | 29 +++++++++++++ >>>> drivers/net/bonding/rte_eth_bond_api.c | 28 ++++++++++++ >>>> drivers/net/bonding/rte_eth_bond_pmd.c | 33 +++++++++++++-- >>>> drivers/net/bonding/version.map | 5 +++ >>>> 7 files changed, 167 insertions(+), 4 deletions(-) >>>> >>>> -- >>>> 2.7.4 >>>> >>> >>> >>> . >>> >