Re: [PATCH v5 0/2] vfio/pci: add msi interrupt affinity support

[Michal Koutný]

On Wed, Jun 12, 2024 at 03:45:48PM GMT, Frederic Griffoul <griffoul@xxxxxxxxx> wrote:
> To be honest my initial idea was to store an affinity mask per vfio group, which
> can be done in the privileged process setting the vfio group/device owner, and
> later apply the mask to each interrupt of each device in the group.
> 
> It would still require to fix the affinity of all the interrupts if
> the vfio group affinity is
> changed (or deliberately ignore this case). And it did not match
> exactly my use case
> where I need the process handling the interrupts to sometimes be able
> to change them
> but always within the cpuset. So I would still need the current patch,
> in addition to
> a new ioctl() to set the affinity mask of a vfio group.

It's not clear to me what is the relation between the process A calling
that ioctl() (and whose cpuset is used to check affinity for)
and a process B that ends up handling the IRQ.
At which place would process B be scheduled on IRQ's affinity CPUs?
(I'm not familiar with VFIO.)

Thanks,
Michal

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