Re: [Qemu-devel] [RFC PATCH RDMA support v4: 03/10] more verbose documentation of the RDMA transport

[Paolo Bonzini]

Il 19/03/2013 18:40, Michael R. Hines ha scritto:
> registration scheme would not work with cgroups because we would be 
> attempting to pin zero pages (for no reason) that cgroups has already
> kicked out, which would defeat the purpose of using cgroups.

Yeah, pinning would be a problem.

> So, if I submit a separate patch to fix this, would you guys review it?
> (Using /dev/pagemap).

Sorry about the ignorance, but what is /dev/pagemap? :)

> Unless there is a better idea? Does KVM expose the necessary mappings?

We could have the balloon driver track the pages.  I and Michael had
some initial work a few months ago on extending the virtio-balloon spec
to allow this.  It went nowhere, though.

Still, at this point this is again an RDMA-specific problem, I don't
think it would be that bad if the first iterations of RDMA didn't
support ballooning/overcommit.

Paolo