Re: [RFC PATCH 0/7] migration/multifd: Introduce storage slots

[Maciej S. Szmigiero]

Hi Fabiano,

On 20.06.2024 23:21, Fabiano Rosas wrote:
> Hi folks,
>
> First of all, apologies for the roughness of the series. I'm off for
> the next couple of weeks and wanted to put something together early
> for your consideration.
>
> This series is a refactoring (based on an earlier, off-list
> attempt[0]), aimed to remove the usage of the MultiFDPages_t type in
> the multifd core. If we're going to add support for more data types to
> multifd, we first need to clean that up.
>
> This time around this work was prompted by Maciej's series[1]. I see
> you're having to add a bunch of is_device_state checks to work around
> the rigidity of the code.
>
> Aside from the VFIO work, there is also the intent (coming back from
> Juan's ideas) to make multifd the default code path for migration,
> which will have to include the vmstate migration and anything else we
> put on the stream via QEMUFile.
>
> I have long since been bothered by having 'pages' sprinkled all over
> the code, so I might be coming at this with a bit of a narrow focus,
> but I believe in order to support more types of payloads in multifd,
> we need to first allow the scheduling at multifd_send_pages() to be
> independent of MultiFDPages_t. So here it is. Let me know what you
> think.

Thanks for the patch set, I quickly glanced at these patches and they
definitely make sense to me.

I guess its latest version could be found in the repo at [2] since
that's where the CI run mentioned below took it from?

> (as I said, I'll be off for a couple of weeks, so feel free to
> incorporate any of this code if it's useful. Or to ignore it
> completely).

I guess you are targeting QEMU 9.2 rather than 9.1 since 9.1 has
feature freeze in about a month, correct?

> CI run: https://gitlab.com/farosas/qemu/-/pipelines/1340992028
>
> 0- https://github.com/farosas/qemu/commits/multifd-packet-cleanups/
> 1- cover.1718717584.git.maciej.szmigiero@oracle.com">https://lore.kernel.org/r/cover.1718717584.git.maciej.szmigiero@oracle.com

[2]: https://gitlab.com/farosas/qemu/-/commits/multifd-pages-decouple

Thanks,
Maciej