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Mon, 20 Apr 2020 07:47:59 -0400 X-MC-Unique: xjeksOD8Ov6PLXW8d2WsIg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6DE9B190B2A0; Mon, 20 Apr 2020 11:47:58 +0000 (UTC) Received: from [10.36.110.18] (unknown [10.36.110.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9FDC19A243; Mon, 20 Apr 2020 11:47:55 +0000 (UTC) To: "Liang, Cunming" , Jerin Jacob , "Fu, Patrick" Cc: "dev@dpdk.org" , "Ye, Xiaolong" , "Hu, Jiayu" , "Wang, Zhihong" References: <89B17B9B05A1964E8D40D6090018F28151277ADF@SHSMSX107.ccr.corp.intel.com> <89B17B9B05A1964E8D40D6090018F28151277C5C@SHSMSX107.ccr.corp.intel.com> <8e4691c5-3e58-fb5d-f1f5-6b9c994c3949@redhat.com> <89B17B9B05A1964E8D40D6090018F28151277D4F@SHSMSX107.ccr.corp.intel.com> From: Maxime Coquelin Autocrypt: addr=maxime.coquelin@redhat.com; keydata= mQINBFOEQQIBEADjNLYZZqghYuWv1nlLisptPJp+TSxE/KuP7x47e1Gr5/oMDJ1OKNG8rlNg kLgBQUki3voWhUbMb69ybqdMUHOl21DGCj0BTU3lXwapYXOAnsh8q6RRM+deUpasyT+Jvf3a gU35dgZcomRh5HPmKMU4KfeA38cVUebsFec1HuJAWzOb/UdtQkYyZR4rbzw8SbsOemtMtwOx YdXodneQD7KuRU9IhJKiEfipwqk2pufm2VSGl570l5ANyWMA/XADNhcEXhpkZ1Iwj3TWO7XR uH4xfvPl8nBsLo/EbEI7fbuUULcAnHfowQslPUm6/yaGv6cT5160SPXT1t8U9QDO6aTSo59N jH519JS8oeKZB1n1eLDslCfBpIpWkW8ZElGkOGWAN0vmpLfdyiqBNNyS3eGAfMkJ6b1A24un /TKc6j2QxM0QK4yZGfAxDxtvDv9LFXec8ENJYsbiR6WHRHq7wXl/n8guyh5AuBNQ3LIK44x0 KjGXP1FJkUhUuruGyZsMrDLBRHYi+hhDAgRjqHgoXi5XGETA1PAiNBNnQwMf5aubt+mE2Q5r qLNTgwSo2dpTU3+mJ3y3KlsIfoaxYI7XNsPRXGnZi4hbxmeb2NSXgdCXhX3nELUNYm4ArKBP LugOIT/zRwk0H0+RVwL2zHdMO1Tht1UOFGfOZpvuBF60jhMzbQARAQABtCxNYXhpbWUgQ29x dWVsaW4gPG1heGltZS5jb3F1ZWxpbkByZWRoYXQuY29tPokCOAQTAQIAIgUCV3u/5QIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQyjiNKEaHD4ma2g/+P+Hg9WkONPaY1J4AR7Uf kBneosS4NO3CRy0x4WYmUSLYMLx1I3VH6SVjqZ6uBoYy6Fs6TbF6SHNc7QbB6Qjo3neqnQR1 71Ua1MFvIob8vUEl3jAR/+oaE1UJKrxjWztpppQTukIk4oJOmXbL0nj3d8dA2QgHdTyttZ1H xzZJWWz6vqxCrUqHU7RSH9iWg9R2iuTzii4/vk1oi4Qz7y/q8ONOq6ffOy/t5xSZOMtZCspu Mll2Szzpc/trFO0pLH4LZZfz/nXh2uuUbk8qRIJBIjZH3ZQfACffgfNefLe2PxMqJZ8mFJXc RQO0ONZvwoOoHL6CcnFZp2i0P5ddduzwPdGsPq1bnIXnZqJSl3dUfh3xG5ArkliZ/++zGF1O wvpGvpIuOgLqjyCNNRoR7cP7y8F24gWE/HqJBXs1qzdj/5Hr68NVPV1Tu/l2D1KMOcL5sOrz 2jLXauqDWn1Okk9hkXAP7+0Cmi6QwAPuBT3i6t2e8UdtMtCE4sLesWS/XohnSFFscZR6Vaf3 gKdWiJ/fW64L6b9gjkWtHd4jAJBAIAx1JM6xcA1xMbAFsD8gA2oDBWogHGYcScY/4riDNKXi lw92d6IEHnSf6y7KJCKq8F+Jrj2BwRJiFKTJ6ChbOpyyR6nGTckzsLgday2KxBIyuh4w+hMq TGDSp2rmWGJjASq5Ag0EVPSbkwEQAMkaNc084Qvql+XW+wcUIY+Dn9A2D1gMr2BVwdSfVDN7 0ZYxo9PvSkzh6eQmnZNQtl8WSHl3VG3IEDQzsMQ2ftZn2sxjcCadexrQQv3Lu60Tgj7YVYRM H+fLYt9W5YuWduJ+FPLbjIKynBf6JCRMWr75QAOhhhaI0tsie3eDsKQBA0w7WCuPiZiheJaL 4MDe9hcH4rM3ybnRW7K2dLszWNhHVoYSFlZGYh+MGpuODeQKDS035+4H2rEWgg+iaOwqD7bg CQXwTZ1kSrm8NxIRVD3MBtzp9SZdUHLfmBl/tLVwDSZvHZhhvJHC6Lj6VL4jPXF5K2+Nn/Su CQmEBisOmwnXZhhu8ulAZ7S2tcl94DCo60ReheDoPBU8PR2TLg8rS5f9w6mLYarvQWL7cDtT d2eX3Z6TggfNINr/RTFrrAd7NHl5h3OnlXj7PQ1f0kfufduOeCQddJN4gsQfxo/qvWVB7PaE 1WTIggPmWS+Xxijk7xG6x9McTdmGhYaPZBpAxewK8ypl5+yubVsE9yOOhKMVo9DoVCjh5To5 aph7CQWfQsV7cd9PfSJjI2lXI0dhEXhQ7lRCFpf3V3mD6CyrhpcJpV6XVGjxJvGUale7+IOp sQIbPKUHpB2F+ZUPWds9yyVxGwDxD8WLqKKy0WLIjkkSsOb9UBNzgRyzrEC9lgQ/ABEBAAGJ Ah8EGAECAAkFAlT0m5MCGwwACgkQyjiNKEaHD4nU8hAAtt0xFJAy0sOWqSmyxTc7FUcX+pbD KVyPlpl6urKKMk1XtVMUPuae/+UwvIt0urk1mXi6DnrAN50TmQqvdjcPTQ6uoZ8zjgGeASZg jj0/bJGhgUr9U7oG7Hh2F8vzpOqZrdd65MRkxmc7bWj1k81tOU2woR/Gy8xLzi0k0KUa8ueB iYOcZcIGTcs9CssVwQjYaXRoeT65LJnTxYZif2pfNxfINFzCGw42s3EtZFteczClKcVSJ1+L +QUY/J24x0/ocQX/M1PwtZbB4c/2Pg/t5FS+s6UB1Ce08xsJDcwyOPIH6O3tccZuriHgvqKP yKz/Ble76+NFlTK1mpUlfM7PVhD5XzrDUEHWRTeTJSvJ8TIPL4uyfzhjHhlkCU0mw7Pscyxn DE8G0UYMEaNgaZap8dcGMYH/96EfE5s/nTX0M6MXV0yots7U2BDb4soLCxLOJz4tAFDtNFtA wLBhXRSvWhdBJZiig/9CG3dXmKfi2H+wdUCSvEFHRpgo7GK8/Kh3vGhgKmnnxhl8ACBaGy9n fxjSxjSO6rj4/MeenmlJw1yebzkX8ZmaSi8BHe+n6jTGEFNrbiOdWpJgc5yHIZZnwXaW54QT UhhSjDL1rV2B4F28w30jYmlRmm2RdN7iCZfbyP3dvFQTzQ4ySquuPkIGcOOHrvZzxbRjzMx1 Mwqu3GQ= Message-ID: Date: Mon, 20 Apr 2020 13:47:53 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [RFC] Accelerating Data Movement for DPDK vHost with DMA Engines 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 4/20/20 9:59 AM, Liang, Cunming wrote: > > >> -----Original Message----- >> From: Jerin Jacob >> Sent: Friday, April 17, 2020 5:55 PM >> To: Fu, Patrick >> Cc: Maxime Coquelin ; dev@dpdk.org; Ye, >> Xiaolong ; Hu, Jiayu ; Wang, >> Zhihong ; Liang, Cunming >> Subject: Re: [dpdk-dev] [RFC] Accelerating Data Movement for DPDK vHost with >> DMA Engines >> >> On Fri, Apr 17, 2020 at 2:56 PM Fu, Patrick wrote: >>> >>> > [...] >>>>> >>>>> I believe it doesn't conflict. The purpose of this RFC is to >>>>> create an async >>>> data path in vhost-user and provide a way for applications to work >>>> with this new path. dmadev is another topic which could be discussed >>>> separately. If we do have the dmadev available in the future, this >>>> vhost async data path could certainly be backed by the new dma >>>> abstraction without major interface change. >>>> >>>> Maybe that one advantage of a dmadev class is that it would be >>>> easier and more transparent for the application to consume. >>>> >>>> The application would register some DMA devices, pass them to the >>>> Vhost library, and then rte_vhost_submit_enqueue_burst and >>>> rte_vhost_poll_enqueue_completed would call the dmadev callbacks directly. >>>> >>>> Do you think that could work? >>>> >>> Yes, this is a workable model. As I said in previous reply, I have no objection to >> make the dmadev. However, what we currently want to do is creating the async >> data path for vhost, and we actually have no preference to the underlying DMA >> device model. I believe our current design of the API proto type /data structures >> are quite common for various DMA acceleration solutions and there is no blocker >> for any new DMA device to adapt to these APIs or extend to a new one. >> >> IMO, as a driver writer, we should not be writing TWO DMA driver. One for vhost >> and other one for rawdev. > It's the most simplest case if statically 1:1 mapping driver (e.g. {port, queue}) to a vhost session {vid, qid}. However, it's not enough scalable to integrate device model with vhost library. There're a few intentions belong to app logic rather than driver, e.g. 1:N load balancing, various device type usages (e.g. vhost zcopy via ethdev) and etc. > > It was not asking to writing two drivers. Each driver remains to offer provider for its own device class, which is independent. App provides the intension (adapter) to associate various device capability to vhost session. > >> If vhost is the first consumer of DMA needed then I think, it make sense to add >> dmadev first. > On the other hand, it's risky to define 'dmadev' according to vhost's flavor before not getting aware of any other candidates. Comparing with kern Async TX DMA API (async_memcpy), RFC is very much focus on S/G buffer but not a async_memcpy. > >> The rawdev DMA driver to dmadev DMA driver conversion will be the driver owner >> job. > It's true when it's necessary. Even that is the case, it's better for vhost to be independent with any device model, moreover vhost usage doesn't have broad enough coverage for a new device class. > >> I think, it makes sense to define the dmadev API and then costume by virtio to >> avoid integration issues. > Vhost is a library but not a app. We'd better avoid to intro either overkill integration logic or extra device model dependence. Thinking at it again, I support Patrick and Steve approach. It will be more flexible than adding dmadev support into the Vhost library directly. For example, this new API could be used to have a cleaner integration of Tx zero-copy, which is kind of hacky for now. Thanks, Maxime > Thanks, > Steve > >> >> >> >>> >>> Thanks, >>> >>> Patrick >>>