Re: [LSF/MM TOPIC] Filesystem-DAX, page-pinning, and RDMA

hch
2018-01-25T16:47:23Z

On Thu, Jan 25, 2018 at 09:08:48AM -0700, Jason Gunthorpe wrote:
> On Wed, Jan 24, 2018 at 11:02:16PM -0800, Dan Williams wrote:
>
> > No, in 3 dimensions since there is a need to support non-ODP RDMA
> > hardware, hypervisors want to coordinate DMA for guests, and non-RDMA
> > hardware also pins memory indefinitely like V4L2. So it's bigger than
> > RDMA, but that will likely be the first consumer of this 'longterm
> > pin' mechanism.
>
> BTW, did you look at VFIO? I think it should also have this problem
> right?

VFIO seems to have the same issue. In practice I don't think people
use file system backed pages for vfio, so it's not as urgent.

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