From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <konstantin.ananyev@intel.com> Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id B0A85C330 for <dev@dpdk.org>; Tue, 21 Jun 2016 15:11:50 +0200 (CEST) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP; 21 Jun 2016 06:11:48 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.26,504,1459839600"; d="scan'208";a="992119831" Received: from irsmsx154.ger.corp.intel.com ([163.33.192.96]) by fmsmga001.fm.intel.com with ESMTP; 21 Jun 2016 06:11:40 -0700 Received: from irsmsx156.ger.corp.intel.com (10.108.20.68) by IRSMSX154.ger.corp.intel.com (163.33.192.96) with Microsoft SMTP Server (TLS) id 14.3.248.2; Tue, 21 Jun 2016 14:10:42 +0100 Received: from irsmsx105.ger.corp.intel.com ([169.254.7.51]) by IRSMSX156.ger.corp.intel.com ([10.108.20.68]) with mapi id 14.03.0248.002; Tue, 21 Jun 2016 14:10:42 +0100 From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com> To: Jerin Jacob <jerin.jacob@caviumnetworks.com> CC: "Lu, Wenzhuo" <wenzhuo.lu@intel.com>, Stephen Hemminger <stephen@networkplumber.org>, "dev@dpdk.org" <dev@dpdk.org>, "Richardson, Bruce" <bruce.richardson@intel.com>, "Chen, Jing D" <jing.d.chen@intel.com>, "Liang, Cunming" <cunming.liang@intel.com>, "Wu, Jingjing" <jingjing.wu@intel.com>, "Zhang, Helin" <helin.zhang@intel.com>, "thomas.monjalon@6wind.com" <thomas.monjalon@6wind.com> Thread-Topic: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support device reset Thread-Index: AQHRyrx6upx+ZylbjUKBoLEe8UVg7p/yAfqAgAB2MgCAAMH0gIAAJ/mAgAAXG4CAAA1AAIAACKQAgAAXzkCAAApgAIAAMyMA Date: Tue, 21 Jun 2016 13:10:40 +0000 Message-ID: <2601191342CEEE43887BDE71AB97725836B74226@irsmsx105.ger.corp.intel.com> References: <1466403870-6840-1-git-send-email-wenzhuo.lu@intel.com> <1466403870-6840-2-git-send-email-wenzhuo.lu@intel.com> <20160620091410.GA9323@localhost.localdomain> <20160620091714.276c186c@xeon-e3> <20160621035124.GC4903@localhost.localdomain> <6A0DE07E22DDAD4C9103DF62FEBC090903488DD1@shsmsx102.ccr.corp.intel.com> <20160621073710.GA30638@localhost.localdomain> <6A0DE07E22DDAD4C9103DF62FEBC090903488F5E@shsmsx102.ccr.corp.intel.com> <20160621085531.GA31880@localhost.localdomain> <2601191342CEEE43887BDE71AB97725836B73FD0@irsmsx105.ger.corp.intel.com> <20160621105751.GA737@localhost.localdomain> In-Reply-To: <20160621105751.GA737@localhost.localdomain> Accept-Language: en-IE, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.180] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support device reset X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK <dev.dpdk.org> List-Unsubscribe: <http://dpdk.org/ml/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://dpdk.org/ml/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <http://dpdk.org/ml/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Tue, 21 Jun 2016 13:11:51 -0000 >=20 > Hi Konstantin, >=20 > > Hi Jerin, > > > > > -----Original Message----- > > > From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com] > > > Sent: Tuesday, June 21, 2016 9:56 AM > > > To: Lu, Wenzhuo > > > Cc: Stephen Hemminger; dev@dpdk.org; Ananyev, Konstantin; Richardson,= Bruce; Chen, Jing D; Liang, Cunming; Wu, Jingjing; > Zhang, > > > Helin; thomas.monjalon@6wind.com > > > Subject: Re: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support devi= ce reset > > > > > > On Tue, Jun 21, 2016 at 08:24:36AM +0000, Lu, Wenzhuo wrote: > > > > Hi Jerin, > > > > > > Hi Wenzhuo, > > > > > > > > > > > > On Mon, Jun 20, 2016 at 02:24:27PM +0800, Wenzhuo Lu wrot= e: > > > > > > > > > > Add an API to reset the device. > > > > > > > > > > It's for VF device in this scenario, kernel PF + DPDK V= F. > > > > > > > > > > When the PF port down->up, APP should call this API to = reset > > > > > > > > > > VF port. Most likely, APP should call it in its managem= ent > > > > > > > > > > thread and guarantee the thread safe. It means APP shou= ld stop > > > > > > > > > > the rx/tx and the device, then reset the device, then r= ecover > > > > > > > > > > the device and rx/tx. > > > > > > > > > > > > > > > > > > Following is _a_ use-case for Device reset. But may be no= t be > > > > > > > > > _the_ use case. IMO, We need to first say expected behavi= or of > > > > > > > > > this API and add a use-case later. > > > > > > > > > > > > > > > > > > Other use-case would be, PCIe VF with functional level re= set for > > > > > > > > > SRIOV migration. > > > > > > > > > Are we on same page? > > > > > > > > > > > > > > > > > > > > > > > > In my experience with Linux devices, this is normally handl= ed by > > > > > > > > the device driver in the start routine. Since any use case= which > > > > > > > > needs this is going to do a stop/reset/start sequence, why = not > > > > > > > > just have the VF device driver do this in the start routine= ?. > > > > > > > > > > > > > > > > Adding yet another API and state transistion if not necessa= ry > > > > > > > > increases the complexity and required test cases for all de= vices. > > > > > > > > > > > > > > I agree with Stephen here.I think if application needs to cal= l start > > > > > > > after the device reset then we could add this logic in start = itself > > > > > > > rather exposing a yet another API > > > > > > Do you mean changing the device_start to include all these acti= ons, stop > > > > > device -> stop queue -> re-setup queue -> start queue -> start de= vice ? > > > > > > > > > > What was the expected API call sequence when you were introduced = this API? > > > > > > > > > > Point was to have implicit device reset in the API call sequence(= Wherever make > > > > > sense for specific PMD) > > > > I think the API call sequence depends on the implementation of the = APP. Let's say if there's not this reset API, APP can use this > API > > > call sequence to handle the PF link down/up event, rte_eth_dev_close = -> rte_eth_rx_queue_setup -> rte_eth_tx_queue_setup - > > > > > rte_eth_dev_start. > > > > Actually our purpose is to use this reset API instead of the API ca= ll sequence. You can see the reset API is not necessary. The > benefit > > > is to save the code for APP. > > > > > > Then I am bit confused with original commit log description. > > > | > > > |It means APP should stop the rx/tx and the device, then reset the > > > |device, then recover the device and rx/tx. > > > | > > > I was under impression that it a low level reset API for this device?= Is > > > n't it? > > > > > > The other issue is generalized outlook of the API, Certain PMD will n= ot > > > have PF link down/up event? Link down/up and only connected to VF and= PF > > > only for configuration. > > > > > > How about fixing it more transparently in PMD driver itself as > > > PMD driver knows the PF link up/down event, Is it possible to > > > recover the VF on that event if its only matter of resetting it? > > > > I think we already went through that discussion on the list. > > Unfortunately with current dpdk design it is hardly possible. > > To achieve that we need to introduce some sort of synchronisation > > between IO and control APIs (locking or so). > > Actually I am not sure why having a special reset function will be a pr= oblem. >=20 > | > |It means APP should stop the rx/tx and the device, then reset the > |device, then recover the device and rx/tx. > | > Just to understand, If application still need to do the stop then what > value addtion reset API brings on the table? If application calls dev_reset() it doesn't need to call dev_stop() before = it. dev_reset() will take care of it.=20 But it needs to make sure that no other thread will try to modify that devi= ce state (either dev_stop/start, or eth_rx_busrst/eth_tx_burst) while the reset op i= s in place. >=20 >=20 > > Yes, it would exist only for VFs, for PF it could be left unimplemented= . > > Though it definitely seems more convenient from user point of view, > > they would know: to handle VF reset event, they just need to call that > > particular function, not to re-implement their own. > What if driver returns "not implemented" then application will have do > generic rte_eth_dev_stop/rte_eth_dev_start. >That way in application perspective we are NOT solving any problem. True, but as I said for PF application would just never receive such event. I suppose it is possible to implement one for PF too, I just don't see much point - as probably no-one will ever use it. Konstantin