On Thu, Sep 21, 2023 at 12:29 PM Parav Pandit <pa...@nvidia.com> wrote: > > > > > From: Jason Wang <jasow...@redhat.com> > > Sent: Thursday, September 21, 2023 9:50 AM > > > Parav, I think I've clarified several times: > > > > migration using the admin command is probably fine in some use cases. > > > This is definitely, was not clear to me. > I am 100% clear now.
Great, thanks. > > > What's not fine, is: > > > > Mandate the admin command to be the only way for migration. > > > For sure, my series did not mandate that either. > I kept asking if we both can converge it will be really good to merge two use > cases, we should. I've replied in another thread. > If we cannot because of technical issues, than both methods to exists to > address two different use cases. > > > Are we on the same page for my concern now? > > > Yes. > > > > What is the advantage of descriptor posting using virtqueue. It is the > > > way of > > virtio spec... > > > > > > > > Well, it is one way to achieve it. > > > > > There may be different way to do all bulk data transfer without > > > > > admin > > > > commands. > > > > > > > > Why is virtqueue the only way to do bulk data transferring? Can't > > > > DMA be initiated by other-way? > > > > > > > > > > Sure, what is the disadvantage of existing mechanism of virtqueue that > > > can do > > following. > > > 1. Ability to do DMA > > > 2. agnostic of the DMA who do not want to do DMA > > > > I don't understand this. > > > Admin commands can work without DMA, right because they are transported using > admin queue. > > > > 3. Ability to multiple command executions in parallel > > > > Each device has their self-contained interface, why can't the commands be > > executed in parallel. > > > Within the device it cannot if the interface is synchronous. > > > > 4. Non blocking interface for driver that does not require any kind of > > > polling > > > > Are you saying the interrupt can only work for virtqueue? > > > No. I am saying if one has to invent a interface that satisfy above needs, it > will become a virtqueue. > And if it is not, one should list those disadvantages and cost of new > interface, and explain its benefits. > Such interface should be generic one too. See my question below. > > > > > > > Why to invent new DMA scheme which at does all the 4 tasks? > > > > It's simply because admin virtqueue can not work for all the cases. I think > > you've > > agreed on this, no? > > > I think it may work for nested case as well at the cost of replicating it on > each device and adding special plumbing to isolate it, so that guest cannot > issue driver notifications to it. > > > > First please list down disadvantages of admin queue + show all 4 things > > > are > > achieved using new DMA interface. > > > That will help to understand why new dma interface is needed. > > > > I can give you a simple example. For example, what happens if we want to > > migrate the owner? Having another owner for this owner is not a good answer. > > That is the nesting, don’t see any difference with other nesting. It's not necessarily nesting. For example how do you migrate PF? Thanks --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org
