Messages in this thread | | | Date | Thu, 31 Jan 2019 10:03:09 -0500 | From | Jerome Glisse <> | Subject | Re: [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma |
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On Thu, Jan 31, 2019 at 09:02:03AM +0100, Christoph Hellwig wrote: > On Wed, Jan 30, 2019 at 01:50:27PM -0500, Jerome Glisse wrote: > > I do not see how VMA changes are any different than using struct page > > in respect to userspace exposure. Those vma callback do not need to be > > set by everyone, in fact expectation is that only handful of driver > > will set those. > > > > How can we do p2p between RDMA and GPU for instance, without exposure > > to userspace ? At some point you need to tell userspace hey this kernel > > does allow you to do that :) > > To do RDMA on a memory region you need struct page backіng to start > with..
No you do not with this patchset and there is no reason to tie RDMA to struct page it does not provide a single feature we would need. So as it can be done without and they are not benefit of using one i do not see why we should use one.
Cheers, Jérôme
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