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Mon, 20 Apr 2020 12:18:53 -0400 X-MC-Unique: jMR4N8kTOv6Owdiez1Z43w-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CC6D38017F5; Mon, 20 Apr 2020 16:18:51 +0000 (UTC) Received: from [10.36.110.18] (unknown [10.36.110.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9EA181001902; Mon, 20 Apr 2020 16:18:49 +0000 (UTC) To: Shahaf Shuler , Matan Azrad , "dev@dpdk.org" , Xiao Wang Cc: Slava Ovsiienko References: <1585826793-28709-1-git-send-email-matan@mellanox.com> <1585826793-28709-2-git-send-email-matan@mellanox.com> <39dba337-f413-0a45-4724-576f05ff07e7@redhat.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: <956f4b42-ecb3-a1f7-4e57-4bfc31c4047a@redhat.com> Date: Mon, 20 Apr 2020 18:18:47 +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 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [dpdk-dev] [PATCH 1/4] vhost: inroduce operation to get vDPA queue stats 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 5:57 PM, Shahaf Shuler wrote: > Monday, April 20, 2020 10:13 AM, Maxime Coquelin: >> Subject: Re: [PATCH 1/4] vhost: inroduce operation to get vDPA queue sta= ts >> >> Hi Shahaf, >> >> On 4/19/20 8:18 AM, Shahaf Shuler wrote: >>> Thursday, April 16, 2020 4:20 PM, Maxime Coquelin: >>>> Subject: Re: [PATCH 1/4] vhost: inroduce operation to get vDPA queue >>>> stats >>>> >>>> Hi Matan, >>>> >>>> On 4/16/20 11:06 AM, Matan Azrad wrote: >>>>> Hi Maxime >>>>> >>>>> Can you point on specific vendor specific counter I suggested? >>>> >>>> No, I can't, but I think we can expect that other vendors may have >>>> other counters they would be interested to dump. >>>> >>>> Maybe Intel has some counters in the IFC that they could dump. >>>> Xiao, any thoughts? >>>> >>>>> I think all of them come directly from virtio protocols. >>>> >>>> exceed_max_chain, for example. Doesn't the spec specify that a >>>> descriptors chain can be as long as the size of the virtqueue? >>>> >>>> Here it seems to indicate the device could support less. >>> >>> Spec allows device to limit the max supported chain (see [1]). >> >> Ha ok, I missed that. Please note that this is only allowed for packed r= ing, it is >> not in the split ring part. >=20 > On my version of spec (csprd01) it is also for split, however it was remo= ved on the latest version not sure why.=20 Problem is that older drivers may assume max chain size is the virtio ring size. By the way, how is the guest Virtio driver made aware of the max chain size? Isn't that missing in the spec? >> >>>> >>>> Also, as the spec evolves, we may have new counters that comes up, so >>>> better to have something flexible from the start IMHO to avoid ABI >>>> breakages. >>> >>> I think there are better ways to address that, e.g.: >>> 1. have some reserved fields for future 2. have the option to point to >>> next item, and by that link chain of stat structures >>> >>>> >>>> Maybe we can have some common xstats names for the Virtio related >>>> counters define in vdpa lib, and then the vendors can specify more >>>> vendor- specific counters if they wish? >>> >>> xstats are good, and we should have it to expose the vendor specific >> counters. The basic counters though, should be simple and vendor agnosti= c >> so that any SW/scripting layer on top of the DPDK can easily use and exp= ose >> it. >>> Hence I think it will be good to have the basic counters with well-defi= ned >> stats structure as part of the vdpa stats API. Is the exceed_max_chain i= s the >> only counter you find odd or there are more? >> >> Problem is that not all the vDPA NIC will implement these counters, so w= ith >> only proposed implementation, the user cannot know whether counter >> value is 0 or counter is just not implemented. For example, the Virtio >> specification does not specify counters, so a full Virtio HW offload dev= ice >> won't have them. >=20 > Yeah, full virtio emulated device is a good example.=20 > I think it is odd virtio doesn=E2=80=99t provide any statistics, e.g. how= would the Netdev on top of the virtio device report anything? How will ppl= debug?=20 > I think sooner or later we will need a way to expose stats.=20 I agree. These missing counters were not blocking when using a SW backend, but with HW Offload I agree such counters would be welcome. >> >> So I think the xstat is the right thing to do, with standardized names f= or the >> standard counters. >=20 > Yeah tend to agree on this one due to the lack of spec statistics.=20 >=20 >> >> Regards, >> Maxime >>>> >>>> Thanks, >>>> Maxime >>> >>> [1] >>> https://eur03.safelinks.protection.outlook.com/?url=3Dhttps%3A%2F%2Fgit= h >>> ub.com%2Foasis-tcs%2Fvirtio-spec%2Fblob%2Fmaster%2Fpacked- >> ring.tex%23L >>> >> 498&data=3D02%7C01%7Cshahafs%40mellanox.com%7C2fbf00c6e115488f >> 483e08 >>> >> d7e4fa4940%7Ca652971c7d2e4d9ba6a4d149256f461b%7C0%7C0%7C6372296 >> 3594175 >>> >> 9512&sdata=3Dm2rPPMM%2Fen9Vkbp%2Fg5xz0MSTWYURh7woI7w5%2B >> b2Zjy8%3D&am >>> p;reserved=3D0 >>> >=20