On 20/10/2023 00:59, Jason Gunthorpe wrote: > On Thu, Oct 19, 2023 at 12:58:29PM +0100, Joao Martins wrote: >> AMD has no such behaviour, though that driver per your earlier suggestion might >> need to wait until -rc1 for some of the refactorings get merged. Hopefully we >> don't need to wait for the last 3 series of AMD Driver refactoring (?) to be >> done as that looks to be more SVA related; Unless there's something more >> specific you are looking for prior to introducing AMD's domain_alloc_user(). > > I don't think we need to wait, it just needs to go on the cleaning list. > I am not sure I followed. This suggests an post-merge cleanups, which goes in different direction of your original comment? But maybe I am just not parsing it right (sorry, just confused) >>> for themselves; so more and more I need to work on something like >>> iommufd_log_perf tool under tools/testing that is similar to the gup_perf to make all >>> performance work obvious and 'standardized' > > We have a mlx5 vfio driver in rdma-core and I have been thinking it > would be a nice basis for building an iommufd tester/benchmarker as it > has a wide set of "easilly" triggered functionality. Oh woah, that's quite awesome; I'll take a closer look; I thought rdma-core support for mlx5-vfio was to do direct usage of the firmware interface, but it appears to be for regular RDMA apps as well. I do use some RDMA to exercise iommu dirty tracking; but it's more like a rudimentary test inside the guest, not something self-contained. I was thinking in something more basic (for starters) device-agnostic to exercise the iommu side part -- I gave gup_test example as that's exactly what I have in mind. Though having in-device knowledge is the ultimate tool to exercise this free of migration problems/overheads/algorithm. Initially I was thinking a DPDK app where you program the device itself, but it is a bit too complex. But if rdma-core can still use mlx5-VFIO while retaining the same semantics of a 'normal' RDMA app (e.g. which registers some MRs and lets you rdma read/write) then this is definitely good foundation. Joao
