[virtio-dev] Re: [virtio-comment] Re: [virtio-dev] Re: [PATCH 0/5] virtio: introduce SUSPEND bit and vq state

Michael S. Tsirkin
2023-10-11T10:20:34Z

On Mon, Oct 09, 2023 at 06:01:42PM +0800, Zhu, Lingshan wrote:
>
>
> On 9/27/2023 11:40 PM, Michael S. Tsirkin wrote:
> > On Wed, Sep 27, 2023 at 04:20:01PM +0800, Zhu, Lingshan wrote:
> > >
> > > On 9/26/2023 6:48 PM, Michael S. Tsirkin wrote:
> > > > On Tue, Sep 26, 2023 at 05:25:42PM +0800, Zhu, Lingshan wrote:
> > > > > We don't want to repeat the discussions, it looks like endless circle with
> > > > > no direction.
> > > > OK let me try to direct this discussion.
> > > > You guys were speaking past each other, no dialog is happening.
> > > > And as long as it goes on no progress will be made and you
> > > > will keep going in circles.
> > > >
> > > > Parav here made an effort and attempted to summarize
> > > > use-cases addressed by your proposal but not his.
> > > > He couldn't resist adding "a yes but" in there oh well.
> > > > But now I hope you know he knows about your use-cases?
> > > >
> > > > So please do the same. Do you see any advantages to Parav's
> > > > proposal as compared to yours? Try to list them and
> > > > if possible try not to accompany the list with "yes but"
> > > > (put it in a separate mail if you must ;) ).
> > > > If you won't be able to see any, let me know and I'll try to help.
> > > >
> > > > Once each of you and Parav have finally heard the other and
> > > > the other also knows he's been heard, that's when we can
> > > > try to make progress by looking for something that addresses
> > > > all use-cases as opposed to endlessly repeating same arguments.
> > > Sure Michael, I will not say "yes but" here.
> > >
> > > From Parav's proposal, he intends to migrate a member device by its owner
> > > device through the admin vq,
> > > thus necessary admin vq commands are introduced in his series.
> > >
> > >
> > > I see his proposal can:
> > > 1) meet some customers requirements without nested and bare-metal
> > > 2) align with Nvidia production
> > > 3) easier to emulate by onboard SOC
> > Is that all you can see?
> >
> > Hint: there's more.
> please help provide more.

Just a small subset off the top of my head:
Error handling.
Extendable to other group types such as SIOV.
Batching of commands
less pci transactioons
Support for keeping some data off-device

which does not mean it's better unconditionally.
are above points clear?

as long as you guys keep not hearing each other we will keep
seeing these flame wars. if you expect everyone on virtio-comment
to follow a 300 message thread you are imo very much mistaken.

> >
> >
> >
> >
> >
> > > The general purpose of his proposal and mine are aligned: migrate virtio
> > > devices.
> > >
> > > Jason has ever proposed to collaborate, please allow me quote his proposal:
> > >
> > > "
> > > Let me repeat once again here for the possible steps to collaboration:
> > >
> > > 1) define virtqueue state, inflight descriptors in the section of
> > > basic facility but not under the admin commands
> > > 2) define the dirty page tracking, device context/states in the
> > > section of basic facility but not under the admin commands
> > > 3) define transport specific interfaces or admin commands to access them
> > > "
> > >
> > > I totally agree with his proposal.
> > >
> > > Does this work for you Michael?
> > >
> > > Thanks
> > > Zhu Lingshan
> > I just doubt very much this will work. What will "define" mean then -
> > not an interface, just a description in english? I think you
> > underestimate the difficulty of creating such definitions that
> > are robust and precise.
> I think we can review the patch to correct the words.
> >
> >
> > Instead I suggest you define a way to submit admin commands that works
> > for nested and bare-metal (i.e. not admin vq, and not with sriov group
> > type). And work with Parav to make live migration admin commands work
> > reasonably will through this interface and with this type.
> why admin commands are better than registers?
> >
>
>
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