Re: [PATCH v3 12/17] vfio/migration: Implement VFIO migration protocol v2

[Jason Gunthorpe]

On Mon, Nov 28, 2022 at 11:50:03AM -0700, Alex Williamson wrote:

> There's a claim here about added complexity that I'm not really seeing.
> It looks like we simply make an ioctl call here and scale our buffer
> based on the minimum of the returned device estimate or our upper
> bound.

I'm not keen on this, for something like mlx5 that has a small precopy
size and large post-copy size it risks running with an under allocated
buffer, which is harmful to performance.

It is a mmap space, if we don't touch the pages they don't get
allocated from the OS, I think this is micro-optimizing.

Jason