On Thu, Oct 17, 2024 at 06:49:30AM -0700, Christoph Hellwig wrote: > On Thu, Oct 17, 2024 at 10:46:44AM -0300, Jason Gunthorpe wrote: > > On Thu, Oct 17, 2024 at 06:12:55AM -0700, Christoph Hellwig wrote: > > > On Thu, Oct 17, 2024 at 10:05:39AM -0300, Jason Gunthorpe wrote: > > > > Broadly I think whatever flow NVMe uses for P2P will apply to ODP as > > > > well. > > > > > > ODP is a lot simpler than NVMe for P2P actually :( > > > > What is your thinking there? I'm looking at the latest patches and I > > would expect dma_iova_init() to accept a phys so it can call > > pci_p2pdma_map_type() once for the whole transaction. It is a slow > > operation. > > You can't do it for the whole transaction. Here is my suggestion > for ODP: > > http://git.infradead.org/?p=users/hch/misc.git;a=shortlog;h=refs/heads/dma-split-wip
OK, this looks very promising. I sketched something similar to the pci-p2pdma changes a while back too. BTW this: iommu: generalize the batched sync after map interface I am hoping to in a direction of adding a gather to the map, just like unmap. So eventually instead of open coding iotlb_sync_map() you'd flush the gather and it would do it. > For NVMe I need to figure out a way to split bios on a per P2P > type boundary as we don't have any space to record if something is a bus > mapped address. Yeah this came up before :\ Can't precompute the p2p type during bio creation, splitting based on pgmap would be good enough. Jason
