Messages in this thread | | | Subject | Re: Enabling peer to peer device transactions for PCIe devices | From | Serguei Sagalovitch <> | Date | Wed, 23 Nov 2016 14:06:34 -0500 |
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On 2016-11-23 12:27 PM, Bart Van Assche wrote: > On 11/23/2016 09:13 AM, Logan Gunthorpe wrote: >> IMO any memory that has been registered for a P2P transaction should be >> locked from being evicted. So if there's a get_user_pages call it needs >> to be pinned until the put_page. The main issue being with the RDMA >> case: handling an eviction when a chunk of memory has been registered as >> an MR would be very tricky. The MR may be relied upon by another host >> and the kernel would have to inform user-space the MR was invalid then >> user-space would have to tell the remote application. > > Hello Logan, > > Are you aware that the Linux kernel already supports ODP (On Demand > Paging)? See also the output of git grep -nHi on.demand.paging. See > also > https://www.openfabrics.org/images/eventpresos/workshops2014/DevWorkshop/presos/Tuesday/pdf/04_ODP_update.pdf. > > Bart. My understanding is that the main problems are (a) h/w support (b) compatibility with IB Verbs semantic.
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