Previous qemu face 2 problems when migrating a fsdax memory backend with RDMA protocol. (1) ibv_reg_mr failed with Operation not supported (2) requester(source) side could receive RNR NAK.
For the (1), we can try to register memory region with ODP feature which has already been implemented in some modern HCA hardware/drivers. For the (2), IB provides advise API to prefetch pages in specific memory region. It can help driver reduce the page fault on responder(destination) side during RDMA_WRITE. Li Zhijian (2): migration/rdma: Try to register On-Demand Paging memory region migration/rdma: advise prefetch write for ODP region migration/rdma.c | 67 ++++++++++++++++++++++++++++++++++++------ migration/trace-events | 2 ++ 2 files changed, 60 insertions(+), 9 deletions(-) -- 2.31.1
