From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail04.ics.ntt-tx.co.jp (mail05.ics.ntt-tx.co.jp [210.232.35.69]) by dpdk.org (Postfix) with ESMTP id ADAF82BAE for ; Thu, 25 Oct 2018 04:55:40 +0200 (CEST) Received: from gwchk03.silk.ntt-tx.co.jp (gwchk03.silk.ntt-tx.co.jp [10.107.0.111]) by mail04.ics.ntt-tx.co.jp (unknown) with ESMTP id w9P2tauj021456; Thu, 25 Oct 2018 11:55:36 +0900 Received: (from root@localhost) by gwchk03.silk.ntt-tx.co.jp (unknown) id w9P2ta0t029253; Thu, 25 Oct 2018 11:55:36 +0900 Received: from gwchk.silk.ntt-tx.co.jp [10.107.0.110] by gwchk03.silk.ntt-tx.co.jp with ESMTP id MAA29252; Thu, 25 Oct 2018 11:55:36 +0900 Received: from imss06.silk.ntt-tx.co.jp (localhost [127.0.0.1]) by ccmail04.silk.ntt-tx.co.jp (unknown) with ESMTP id w9P2taCg008107; Thu, 25 Oct 2018 11:55:36 +0900 Received: from imss06.silk.ntt-tx.co.jp (localhost [127.0.0.1]) by imss06.silk.ntt-tx.co.jp (unknown) with ESMTP id w9P2tatV012299; Thu, 25 Oct 2018 11:55:36 +0900 Received: from ccmail04 (smtp03.silk.ntt-tx.co.jp [10.107.0.135]) by imss06.silk.ntt-tx.co.jp (unknown) with SMTP id w9P2taru012296; Thu, 25 Oct 2018 11:55:36 +0900 Date: Thu, 25 Oct 2018 11:54:35 +0900 From: Hideyuki Yamashita In-Reply-To: <3271179.oIOqrX44Jl@xps> References: <201810230152.w9N1qgQD015354@ccmail04.silk.ntt-tx.co.jp> <3271179.oIOqrX44Jl@xps> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.74 [ja] X-CCMail7: CC-Mail-V7.0.2-Client-Relayed Message-Id: <201810250255.w9P2tC3e007738@ccmail04.silk.ntt-tx.co.jp> X-TM-AS-MML: No X-CC-Mail-RelayStamp: CC-Mail-V5.14-Server To: Thomas Monjalon Cc: dev@dpdk.org, Gaetan Rivet Subject: Re: [dpdk-dev] How to replace rte_eth_dev_attach with rte_eal_hotplug_add X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 25 Oct 2018 02:55:41 -0000 Hi, > Yes it may work with most of the drivers. Question for my understadnding. You said that most of the drivers assign only one port when hotplug_add is called, right? Then what is the exception? What kind of device/driver assign multiple ports? My program attach to - vhost pmd - pcap pmd - null pmd and I understand those device(?) assign only one port per attach. BR, Hideyuki Yamashita NTT TechnoCross > Hi, > > 23/10/2018 03:52, Hideyuki Yamashita: > > Hi, > > > > Thanks for your guidance again. > > > > Q1. > > Is following my understanding correct? > > If a device has multiple port, then "rte_eth_dev_get_port_by_name" > > will NOT work becauase it uses strcmp and needs "exact match" > > of the device name. > > New iterator RTE_ETH_FOREACH_MATCHING_DEV takes care > > of this issue and even if the name is "parially matched" with > > the given parameter(user provided devargs). > > Yes > > > Q2. > > If my program only handles devices which create only one port, > > then "rte_eth_dev_get_port_by_name" may work. > > (Though such a program does not have extensibility and > > only workable under certain limitations) > > Yes it may work with most of the drivers. > > > Q3. > > When new iterator RTE_ETH_FOREACH_MATCHING_DEV > > will be available? > > Do I have to wait 18.11 release or can I get those in git before release? > > Better to wait 18.11. > > > I agree with your guidance that RTE_ETH_FOREACH_MATCHING_DEV > > is much better than using "rte_eth_dev_get_port_by_name" with regard > > to handle devices which create multiple port. > > But I need to replace existing deprecated attach/detach APIs to new > > codes to maintain continuity of my product. > > We do not remove a method without a replacement. > You can use rte_eth_dev_attach() until 18.08, > and switch to the new iterator with 18.11. > > > > > Hi, > > > > > > The better approach is using RTE_ETH_FOREACH_MATCHING_DEV for 2 reasons: > > > - it is a loop, so work if multiple ports are matching > > > - it uses devargs parameter, which is what the user requests > > > > > > Note: your code assumes that the ethdev name is devargs.name. > > > It can be true by chance, but nothing forces drivers to assign port names > > > this way. It will be wrong, for sure, if a device has multiple ports. > > > > > > > > > 22/10/2018 13:24, Hideyuki Yamashita: > > > > Hello Thomas, > > > > > > > > Thanks for your info. > > > > What is the difference between using > > > > rte_eth_dev_get_port_by_name and > > > > RTE_ETH_FOREACH_MATCHING_DEV? > > > > > > > > I think using rte_eth_dev_get_port_by_name is > > > > workable. > > > > (In fact I modified my code already and it worked with no problem) > > > > > > > > So my question is "what is the difference" and "which is better approach". > > > > > > > > Thanks and BR, > > > > Hideyuki Yamashita > > > > NTT TechnoCross > > > > > > > > > Hi, > > > > > > > > > > I am actively working on it. > > > > > Look how rte_eth_dev_attach is replaced in testpmd: > > > > > https://patches.dpdk.org/patch/47019/ > > > > > It is using a new ethdev iterator RTE_ETH_FOREACH_MATCHING_DEV. > > > > > > > > > > > > > > > 22/10/2018 06:34, Hideyuki Yamashita: > > > > > > Dear Thomas and all, > > > > > > > > > > > > About a month ago, I posted the topic related with > > > > > > how to replace rte_eth_dev_attach. > > > > > > > > > > > > Following your advice, > > > > > > my code would be as below: > > > > > > (Old code using deprecated API is commented out) > > > > > > > > > > > > rte_eth_dev_get_port_by_name is used to retrieve dpdk port > > > > > > after rte_eal_hotplug_add. > > > > > > Note that my application is just one of the dpdk applications(in the host) > > > > > > and within the process, only one thread handles device attatch/detach. > > > > > > (No race condition with regard to device hot_plug will > > > > > > not take place) > > > > > > ------------------------------------------------------------------- > > > > > > //ret = rte_eth_dev_attach(devargs, &vhost_port_id); > > > > > > //if (ret < 0) > > > > > > // return ret; > > > > > > > > > > > > struct rte_devargs da; > > > > > > > > > > > > memset(&da, 0, sizeof(da)); > > > > > > > > > > > > /* parse devargs */ > > > > > > if (rte_devargs_parse(&da, devargs)) > > > > > > return -1; > > > > > > ret = rte_eal_hotplug_add(da.bus->name, da.name, da.args); > > > > > > if (ret < 0) { > > > > > > free(da.args); > > > > > > return ret; > > > > > > } > > > > > > free(da.args); > > > > > > ret = rte_eth_dev_get_port_by_name(da.name, &vhost_port_id); > > > > > > if (ret < 0) > > > > > > return ret; > > > > > > ----------------------------------------------------------------------------- > > > > > > > > > > > > If you have any concerns/additional advices, please let me know. > > > > > > > > > > > > BR, > > > > > > Hideyuki Yamashita > > > > > > NTT TechnoCross > > > > > > > > > > > > > > > > > > > 27/09/2018 12:40, Hideyuki Yamashita: > > > > > > > > Dear Thomas, > > > > > > > > > > > > > > > > Thansk for your answer. > > > > > > > > Please see inline. > > > > > > > > > > > > > > > > > 27/09/2018 03:38, Hideyuki Yamashita: > > > > > > > > > > Dear Thomas, > > > > > > > > > > > > > > > > > > > > Thanks for your answer. > > > > > > > > > > It took me a little time to digest answer. > > > > > > > > > > Please see inline. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > 21/09/2018 09:19, Hideyuki Yamashita: > > > > > > > > > > > > Dear Gaetan and Thomas, > > > > > > > > > > > > > > > > > > > > > > > > Thanks for your answer. > > > > > > > > > > > > Please see inline. > > > > > > > > > > > > > > > > > > > > > > > > > 20/09/2018 11:09, Ga?an Rivet: > > > > > > > > > > > > > > On Thu, Sep 20, 2018 at 05:46:37PM +0900, Hideyuki Yamashita wrote: > > > > > > > > > > > > > > > Hello, > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > From dpdk 18.08 release rte_eth_dev_attach and > > > > > > > > > > > > > > > rte_eth_dev_detach becom deprecated API and > > > > > > > > > > > > > > > it is recommended to replace with rte_eal_hotplug_add > > > > > > > > > > > > > > > and rte_eal_hotplug_remove. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > My program uses above mentioned deprecated APIs > > > > > > > > > > > > > > > and have to replace those. > > > > > > > > > > > > > > > Note that my program uses attach to attach vhost, pcap pmd. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > My question is whether it is correct to replace those as following: > > > > > > > > > > > > > > > find rte_eth_dev_attach function in rte_ethdev.c and > > > > > > > > > > > > > > > migrate those content into my program. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > e.g. > > > > > > > > > > > > > > > lib/librte_ethdev/rte_ethdev.c line 643-686 for attach > > > > > > > > > > > > > > > lib/librte_ethdev/rte_ethdev.c line 690-720 for detach > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Your advice/guidance are much appreciated. > > > > > > > > > > > > > > > Thanks! > > > > > > > > > > > > > > > > > > > > > > > > > > > > Hello Hideyuki, > > > > > > > > > > > > > > > > > > > > > > > > > > > > You could use this code for guidance, while leaving the ethdev > > > > > > > > > > > > > > specificities such as verifying the eth_dev_count_total(). The hotplug > > > > > > > > > > > > > > function would already return an error if the PMD was not able to create > > > > > > > > > > > > > > the necessary devices. > > > > > > > > > > > > > > > > > > > > > > > > > > > > The main issue might be to find the port_id of your new port. > > > > > > > > > > > > > > You won't be able to use eth_dev_last_created_port, so you would have to > > > > > > > > > > > > > > iterate over the ethdev using RTE_ETH_FOREACH_DEV and find the one > > > > > > > > > > > > > > matching your parameters (you might for example match the rte_device > > > > > > > > > > > > > > name with the name you used in hotplug_add, as there is no standard > > > > > > > > > > > > > > naming scheme at the ethdev level). > > > > > > > > > > > > First of all, thank for your answering to my question. > > > > > > > > > > > > But I have questions. > > > > > > > > > > > > (Sorry, I have poor knowledge about dpdk and have many basic questions) > > > > > > > > > > > > > > > > > > > > > > > > Q1. > > > > > > > > > > > > Why eth_dev_last_created_port can not be used? > > > > > > > > > > > > When I look into rte_eth_dev_atthach in 18.08, it calls > > > > > > > > > > > > > > > > > > > > > > > > *port_id = eth_dev_last_created_port; > > > > > > > > > > > > > > > > > > > > > > > > at the end of the function. > > > > > > > > > > > > > > > > > > > > > > You can have a race condition. > > > > > > > > > > Please elaborate me a bit more. > > > > > > > > > > > > > > > > > > > > Is it correct understanding that race condition > > > > > > > > > > includes > > > > > > > > > > - read information before port is available > > > > > > > > > > - other device may be plugged (or unplugged) > > > > > > > > > > and so using "eth_dev_last_created_port" is > > > > > > > > > > NOT reliable? > > > > > > > > > > > > > > > > > > I am thinking about the second one only. > > > > > > > > > > > > > > > > If we assume there is only one DPDK application > > > > > > > > inside the host and within the application, only one thread > > > > > > > > handles attach/detach of devices, then is it ok to use > > > > > > > > > > > > *port_id = eth_dev_last_created_port; > > > > > > > > because there seems no possiblity race condition > > > > > > > > takes place? > > > > > > > > > > > > > > If you are never probing a new port outside of this thread, > > > > > > > I guess it's OK. > > > > > > > Take care of not attaching from the interrupt thread too! > > > >