OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.


Help: OASIS Mailing Lists Help | MarkMail Help

virtio-comment message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]

Subject: Re: [virtio-comment] Re: [PATCH v1 3/8] device-context: Define the device context fields for device migration

On 10/20/2023 8:54 PM, Parav Pandit wrote:
From: Zhu, Lingshan <lingshan.zhu@intel.com>
Sent: Friday, October 20, 2023 3:01 PM

On 10/19/2023 6:33 PM, Parav Pandit wrote:
From: Zhu, Lingshan <lingshan.zhu@intel.com>
Sent: Thursday, October 19, 2023 2:48 PM

On 10/19/2023 5:14 PM, Michael S. Tsirkin wrote:
On Thu, Oct 19, 2023 at 09:13:16AM +0000, Parav Pandit wrote:
Oh, really? Quite interesting, do you want to move all config
space fields in VF to admin vq? Have a plan?
Not in my plan for spec 1.4 time frame.
I do not want to divert the discussion, would like to focus on
migration phases.
Lets please discuss in some other dedicated thread.
Possibly, if there's a way to send admin commands to vf itself then
Lingshan will be happy?
still need to prove why admin commands are better than registers.
Virtio spec development is not proof based approach. Please stop asking for it.

I tried my best to have technical answer in [1].
I explained that registers simply do not work for passthrough mode (if
this is what you are asking when you are asking prove its better).
They can work for non_passthrough mediated mode.

A member device may do admin commands using registers. Michael and I are
discussing presently in the same thread.
Since there are multiple things to be done for device migration, dedicated
register set for each functionality do not scale well, hard to maintain and
A register holding a command content make sense.

Now, with that, if this can be useful only for non_passthrough, I made humble
request to transport them using AQ, this way, you get all benefits of AQ.
And trying to understand, why AQ cannot possible or inferior?

If you have commands like suspend/resume device, register or queue
transport simply donât work, because it's wrong to bifurcate the device with
such weird API.
If you want to biferacate for mediation software, it probably makes sense to
operate at each VQ level, config space level. Such are very different commands
than passthrough.
I think vdpa has demonstrated that very well on how to do specific work for
specific device type. So some of those work can be done using AQ.
We have been through your statement for many times.
This is not about how many times you repeated, if you think this is true, you
need to prove that with solid evidence.

I will not respond to this comment anymore.
Ok if you choose not to respond.

For pass-through, I still recommend you to take a reference of current
virito-pci implementation, it works for pass-through, right?
What do you mean by current virtio-pci implementation?
current virito-pci works for pass-through

For scale, I already told you for many times that they are per-device
facilities. How can a per-device facility not scale?
Each VF device must implement new set of on-chip memory-based registers which demands more power, die area which does not scale efficiently to thousands of VFs.
that can be fpga gates or SOC implementing new features, you think that is a waste?

vDPA works fine on config space.

So, if you still insist admin vq is better than config space like in
other thread you have concluded, you may imply that config space
interfaces should be re-factored to admin vq.
Whatever is done in past is done, there is no way to change history.
An new non init time registers should not be placed in device specific config space as virtio spec has clear guideline on it for good.
Device context reading, dirty page address reading, changing vf device modes, all of these are clearly not a init time settings.
Hence, they do not belong to the registers.
reset vq? and you get it from Appendix B. Creating New Device Types, are we implementing a new type of device???

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]