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
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
$ 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.