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Tue, 17 Mar 2020 05:53:41 -0400 X-MC-Unique: 6BgoLzl4OP-AVFsi7DdoBg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6EC14107ACC4; Tue, 17 Mar 2020 09:53:40 +0000 (UTC) Received: from [10.36.110.21] (unknown [10.36.110.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A5E2619C58; Tue, 17 Mar 2020 09:53:38 +0000 (UTC) To: Jiayu Hu , dev@dpdk.org Cc: xiaolong.ye@intel.com, zhihong.wang@intel.com References: <1584436885-18651-1-git-send-email-jiayu.hu@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: <370798e0-b006-4a33-d8d9-1aea7bf4af49@redhat.com> Date: Tue, 17 Mar 2020 10:53:35 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <1584436885-18651-1-git-send-email-jiayu.hu@intel.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Subject: Re: [dpdk-dev] [PATCH 0/4] Support DMA-accelerated Tx operations for vhost-user PMD 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" Hi Jiayu, On 3/17/20 10:21 AM, Jiayu Hu wrote: > In vhost-user PMD's Tx operations, where data movement is heavily involve= d, > performing large memory copies usually takes up a major part of CPU cycle= s > and becomes the hot spot. To offload expensive memory operations from the > CPU, this patch set proposes to leverage DMA engines, e.g., I/OAT, a DMA > engine in the Intel's processor, to accelerate large copies for vhost-use= r. >=20 > Large copies are offloaded from the CPU to the DMA in an asynchronous > manner. The CPU just submits copy jobs to the DMA but without waiting > for its copy completion. Thus, there is no CPU intervention during data > transfer; we can save precious CPU cycles and improve the overall > throughput for vhost-user PMD based applications, like OVS. During > packet transmission, it offloads large copies to the DMA and performs > small copies by the CPU, due to startup overheads associated with the DMA= . >=20 > vhost-user PMD is able to support various DMA engines, but it just > supports I/OAT devices currently. In addition, I/OAT acceleration is only > enabled for Tx operations of split rings. Users can explicitly assign a > I/OAT device to a queue by the parameter 'dmas'. However, one I/OAT devic= e > can only be used by one queue, and a queue can use one I/OAT device at a > time. >=20 > We measure the performance in testpmd. With 1024 bytes packets, compared > with the original SW data path, DMA-enabled vhost-user PMD can improve > the throughput around 20%~30% in the VM2VM and PVP cases. Furthermore, > with larger packets, the throughput improvement will be higher. I'm not sure it should be done like that for several reasons. First, it seems really complex for the user to get the command line right. There is no mention in the doc patch on how to bind the DMAs to the DPDK application. Are all the DMAs on the system capable of doing it? I think it should be made transparent to the user, who should not have to specify the DMA device address in command line. The user should just pass a devarg specifying he wants to use DMAs, if available. Second, it looks too much vendor-specific. IMHO, we should have a DMA framework, so that the driver can request DMA channels based on capabilities. Also, I don't think implementing ring processing in the Vhost PMD is welcome, Vhost PMD should just be a wrapper for the Vhost library. Doing that in Vhost PMD causes code duplication, and will be a maintenance burden on the long run. As IOAT is a kind of acceleration, why not implement it through the vDPA framework? vDPA framework should be extended to support this kind of acceleration which requires some CPU processing, as opposed to full offload of the ring processing as it only supports today. Kind regards, Maxime > Jiayu Hu (4): > vhost: populate guest memory for DMA-accelerated vhost-user > net/vhost: setup vrings for DMA-accelerated datapath > net/vhost: leverage DMA engines to accelerate Tx operations > doc: add I/OAT acceleration support for vhost-user PMD >=20 > doc/guides/nics/vhost.rst | 14 + > drivers/Makefile | 2 +- > drivers/net/vhost/Makefile | 6 +- > drivers/net/vhost/internal.h | 160 +++++++ > drivers/net/vhost/meson.build | 5 +- > drivers/net/vhost/rte_eth_vhost.c | 308 +++++++++++--- > drivers/net/vhost/virtio_net.c | 861 ++++++++++++++++++++++++++++++++= ++++++ > drivers/net/vhost/virtio_net.h | 288 +++++++++++++ > lib/librte_vhost/rte_vhost.h | 1 + > lib/librte_vhost/socket.c | 20 + > lib/librte_vhost/vhost.h | 2 + > lib/librte_vhost/vhost_user.c | 3 +- > 12 files changed, 1597 insertions(+), 73 deletions(-) > create mode 100644 drivers/net/vhost/internal.h > create mode 100644 drivers/net/vhost/virtio_net.c > create mode 100644 drivers/net/vhost/virtio_net.h >=20