From: Jason Wang <jasowang@redhat.com>
To: "Parav Pandit" <parav@nvidia.com>,
"Daniel P. Berrangé" <berrange@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
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Yan Zhao <yan.y.zhao@intel.com>,
Parav Pandit <parav@mellanox.com>,
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Subject: Re: device compatibility interface for live migration with assigned devices
Date: Wed, 19 Aug 2020 14:48:34 +0800 [thread overview]
Message-ID: <115147a9-3d8c-aa95-c43d-251a321ac152@redhat.com> (raw)
In-Reply-To: <BY5PR12MB4322CD6B3C697B6F1807ECBFDC5D0@BY5PR12MB4322.namprd12.prod.outlook.com>
On 2020/8/19 下午1:26, Parav Pandit wrote:
>
>> From: Jason Wang <jasowang@redhat.com>
>> Sent: Wednesday, August 19, 2020 8:16 AM
>
>> On 2020/8/18 下午5:32, Parav Pandit wrote:
>>> Hi Jason,
>>>
>>> From: Jason Wang <jasowang@redhat.com>
>>> Sent: Tuesday, August 18, 2020 2:32 PM
>>>
>>>
>>> On 2020/8/18 下午4:55, Daniel P. Berrangé wrote:
>>> On Tue, Aug 18, 2020 at 11:24:30AM +0800, Jason Wang wrote:
>>> On 2020/8/14 下午1:16, Yan Zhao wrote:
>>> On Thu, Aug 13, 2020 at 12:24:50PM +0800, Jason Wang wrote:
>>> On 2020/8/10 下午3:46, Yan Zhao wrote:
>>> driver is it handled by?
>>> It looks that the devlink is for network device specific, and in
>>> devlink.h, it says include/uapi/linux/devlink.h - Network physical
>>> device Netlink interface, Actually not, I think there used to have
>>> some discussion last year and the conclusion is to remove this
>>> comment.
>>>
>>> [...]
>>>
>>>> Yes, but it could be hard. E.g vDPA will chose to use devlink (there's a long
>> debate on sysfs vs devlink). So if we go with sysfs, at least two APIs needs to be
>> supported ...
>>> We had internal discussion and proposal on this topic.
>>> I wanted Eli Cohen to be back from vacation on Wed 8/19, but since this is
>> active discussion right now, I will share the thoughts anyway.
>>> Here are the initial round of thoughts and proposal.
>>>
>>> User requirements:
>>> ---------------------------
>>> 1. User might want to create one or more vdpa devices per PCI PF/VF/SF.
>>> 2. User might want to create one or more vdpa devices of type net/blk or
>> other type.
>>> 3. User needs to look and dump at the health of the queues for debug purpose.
>>> 4. During vdpa net device creation time, user may have to provide a MAC
>> address and/or VLAN.
>>> 5. User should be able to set/query some of the attributes for
>>> debug/compatibility check 6. When user wants to create vdpa device, it needs
>> to know which device supports creation.
>>> 7. User should be able to see the queue statistics of doorbells, wqes
>>> etc regardless of class type
>>
>> Note that wqes is probably not something common in all of the vendors.
> Yes. I virtq descriptors stats is better to monitor the virtqueues.
>
>>
>>> To address above requirements, there is a need of vendor agnostic tool, so
>> that user can create/config/delete vdpa device(s) regardless of the vendor.
>>> Hence,
>>> We should have a tool that lets user do it.
>>>
>>> Examples:
>>> -------------
>>> (a) List parent devices which supports creating vdpa devices.
>>> It also shows which class types supported by this parent device.
>>> In below command two parent devices support vdpa device creation.
>>> First is PCI VF whose bdf is 03.00:5.
>>> Second is PCI SF whose name is mlx5_sf.1
>>>
>>> $ vdpa list pd
>>
>> What did "pd" mean?
>>
> Parent device which support creation of one or more vdpa devices.
> In a system there can be multiple parent devices which may be support vdpa creation.
> User should be able to know which devices support it, and when user creates a vdpa device, it tells which parent device to use for creation as done in below vdpa dev add example.
>>> pci/0000:03.00:5
>>> class_supports
>>> net vdpa
>>> virtbus/mlx5_sf.1
>>
>> So creating mlx5_sf.1 is the charge of devlink?
>>
> Yes.
> But here vdpa tool is working at the parent device identifier {bus+name} instead of devlink identifier.
>
>
>>> class_supports
>>> net
>>>
>>> (b) Now add a vdpa device and show the device.
>>> $ vdpa dev add pci/0000:03.00:5 type net
>>
>> So if you want to create devices types other than vdpa on
>> pci/0000:03.00:5 it needs some synchronization with devlink?
> Please refer to FAQ-1, a new tool is not linked to devlink because vdpa will evolve with time and devlink will fall short.
> So no, it doesn't need any synchronization with devlink.
> As long as parent device exist, user can create it.
> All synchronization will be within drivers/vdpa/vdpa.c
> This user interface is exposed via new netlink family by doing genl_register_family() with new name "vdpa" in drivers/vdpa/vdpa.c.
Just to make sure I understand here.
Consider we had virtbus/mlx5_sf.1. Process A want to create a vDPA
instance on top of it but Process B want to create a IB instance. Then I
think some synchronization is needed at at least parent device level?
>
>>
>>> $ vdpa dev show
>>> vdpa0@pci/0000:03.00:5 type net state inactive maxqueues 8 curqueues 4
>>>
>>> (c) vdpa dev show features vdpa0
>>> iommu platform
>>> version 1
>>>
>>> (d) dump vdpa statistics
>>> $ vdpa dev stats show vdpa0
>>> kickdoorbells 10
>>> wqes 100
>>>
>>> (e) Now delete a vdpa device previously created.
>>> $ vdpa dev del vdpa0
>>>
>>> Design overview:
>>> -----------------------
>>> 1. Above example tool runs over netlink socket interface.
>>> 2. This enables users to return meaningful error strings in addition to code so
>> that user can be more informed.
>>> Often this is missing in ioctl()/configfs/sysfs interfaces.
>>> 3. This tool over netlink enables syscaller tests to be more usable like other
>> subsystems to keep kernel robust
>>> 4. This provides vendor agnostic view of all vdpa capable parent and vdpa
>> devices.
>>> 5. Each driver which supports vdpa device creation, registers the parent device
>> along with supported classes.
>>> FAQs:
>>> --------
>>> 1. Why not using devlink?
>>> Ans: Because as vdpa echo system grows, devlink will fall short of extending
>> vdpa specific params, attributes, stats.
>>
>>
>> This should be fine but it's still not clear to me the difference
>> between a vdpa netlink and a vdpa object in devlink.
>>
> The difference is a vdpa specific tool work at the parent device level.
> It is likely more appropriate to because it can self-contain everything needed to create/delete devices, view/set features, stats.
> Trying to put that in devlink will fall short as devlink doesn’t have vdpa definitions.
> Typically when a class/device subsystem grows, its own tool is wiser like iproute2/ip, iproute2/tc, iproute2/rdma.
Ok, I see.
Thanks
next prev parent reply other threads:[~2020-08-19 6:49 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 23:29 device compatibility interface for live migration with assigned devices Yan Zhao
2020-07-14 10:21 ` Daniel P. Berrangé
2020-07-14 12:33 ` Sean Mooney
[not found] ` <20200714110148.0471c03c@x1.home>
[not found] ` <eb705c72cdc8b6b8959b6ebaeeac6069a718d524.camel@redhat.com>
2020-07-14 21:15 ` Sean Mooney
2020-07-14 16:16 ` Alex Williamson
2020-07-14 16:47 ` Daniel P. Berrangé
2020-07-14 20:47 ` Alex Williamson
2020-07-15 9:16 ` Daniel P. Berrangé
2020-07-14 17:19 ` Dr. David Alan Gilbert
2020-07-14 20:59 ` Alex Williamson
2020-07-15 8:20 ` Yan Zhao
2020-07-15 8:49 ` Feng, Shaohe
2020-07-17 14:59 ` Alex Williamson
2020-07-17 18:03 ` Dr. David Alan Gilbert
2020-07-17 18:30 ` Alex Williamson
2020-07-15 8:23 ` Dr. David Alan Gilbert
[not found] ` <CAH7mGatPWsczh_rbVhx4a+psJXvkZgKou3r5HrEQTqE7SqZkKA@mail.gmail.com>
2020-07-17 15:18 ` Alex Williamson
2020-07-16 4:16 ` Jason Wang
2020-07-16 8:32 ` Yan Zhao
2020-07-16 9:30 ` Jason Wang
2020-07-17 16:12 ` Alex Williamson
2020-07-20 3:41 ` Jason Wang
2020-07-20 10:39 ` Sean Mooney
2020-07-21 2:11 ` Jason Wang
2020-07-21 0:51 ` Yan Zhao
2020-07-27 7:24 ` Yan Zhao
2020-07-27 22:23 ` Alex Williamson
2020-07-29 8:05 ` Yan Zhao
2020-07-29 11:28 ` Sean Mooney
2020-07-29 19:12 ` Alex Williamson
2020-07-30 3:41 ` Yan Zhao
2020-07-30 13:24 ` Sean Mooney
2020-07-30 17:29 ` Alex Williamson
2020-08-04 8:37 ` Yan Zhao
2020-08-05 9:44 ` Dr. David Alan Gilbert
2020-07-30 1:56 ` Yan Zhao
2020-07-30 13:14 ` Sean Mooney
2020-08-04 16:35 ` Cornelia Huck
2020-08-05 2:22 ` Jason Wang
2020-08-05 2:16 ` Yan Zhao
2020-08-05 2:41 ` Jason Wang
2020-08-05 7:56 ` Jiri Pirko
2020-08-05 8:02 ` Jason Wang
2020-08-05 9:33 ` Yan Zhao
2020-08-05 10:53 ` Jiri Pirko
2020-08-05 11:35 ` Sean Mooney
2020-08-07 11:59 ` Cornelia Huck
2020-08-13 15:33 ` Cornelia Huck
2020-08-13 19:02 ` Eric Farman
2020-08-17 6:38 ` Cornelia Huck
2020-08-10 7:46 ` Yan Zhao
2020-08-13 4:24 ` Jason Wang
2020-08-14 5:16 ` Yan Zhao
2020-08-14 12:30 ` Sean Mooney
2020-08-17 1:52 ` Yan Zhao
2020-08-18 3:24 ` Jason Wang
2020-08-18 8:55 ` Daniel P. Berrangé
2020-08-18 9:06 ` Cornelia Huck
2020-08-18 9:24 ` Daniel P. Berrangé
2020-08-18 9:38 ` Cornelia Huck
[not found] ` <3a073222-dcfe-c02d-198b-29f6a507b2e1@redhat.com>
2020-08-18 9:16 ` Daniel P. Berrangé
2020-08-18 9:36 ` Cornelia Huck
2020-08-18 9:39 ` Parav Pandit
2020-08-19 3:30 ` Yan Zhao
2020-08-19 5:58 ` Parav Pandit
2020-08-19 9:41 ` Jason Wang
2020-08-19 6:57 ` [ovirt-devel] " Jason Wang
2020-08-19 6:59 ` Yan Zhao
2020-08-19 7:39 ` Jason Wang
2020-08-19 8:13 ` Yan Zhao
2020-08-19 9:28 ` Jason Wang
2020-08-20 12:27 ` Cornelia Huck
2020-08-21 3:14 ` Jason Wang
2020-08-21 14:52 ` Cornelia Huck
2020-08-31 3:07 ` Jason Wang
2020-08-19 17:50 ` Alex Williamson
2020-08-20 0:18 ` Yan Zhao
2020-08-20 3:13 ` Alex Williamson
2020-08-20 3:09 ` Yan Zhao
2020-08-19 2:54 ` Jason Wang
2020-08-20 0:39 ` Yan Zhao
2020-08-20 1:29 ` Sean Mooney
2020-08-20 4:01 ` Yan Zhao
2020-08-20 5:16 ` Sean Mooney
2020-08-20 6:27 ` Yan Zhao
2020-08-20 13:24 ` Sean Mooney
2020-08-26 8:54 ` Yan Zhao
2020-08-20 3:22 ` Alex Williamson
2020-08-20 3:16 ` Yan Zhao
2020-08-25 14:39 ` Cornelia Huck
2020-08-26 6:41 ` Yan Zhao
2020-08-28 13:47 ` Cornelia Huck
2020-08-28 14:04 ` Sean Mooney
2020-08-31 4:43 ` Yan Zhao
2020-09-08 14:41 ` Cornelia Huck
2020-09-09 2:13 ` Yan Zhao
2020-09-10 12:38 ` Cornelia Huck
2020-09-10 12:50 ` Sean Mooney
2020-09-10 18:02 ` Alex Williamson
2020-09-11 0:56 ` Yan Zhao
2020-09-11 10:08 ` Cornelia Huck
2020-09-11 10:18 ` Tian, Kevin
2020-09-11 16:51 ` Alex Williamson
2020-09-14 13:48 ` Zeng, Xin
2020-09-14 14:44 ` Alex Williamson
2020-09-09 5:37 ` Yan Zhao
2020-08-31 2:23 ` Yan Zhao
2020-08-19 2:38 ` Jason Wang
2020-08-18 9:32 ` Parav Pandit
2020-08-19 2:45 ` Jason Wang
2020-08-19 5:26 ` Parav Pandit
2020-08-19 6:48 ` Jason Wang [this message]
2020-08-19 6:53 ` Parav Pandit
2020-07-29 19:05 ` Dr. David Alan Gilbert
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