On Thu, Nov 10, 2011 at 01:12:00PM -0800, Stepan Moskovchenko wrote: > I have been experimenting with an iommu_map_range call, which maps a > given scatterlist of discontiguous physical pages into a contiguous > virtual region at a given IOVA. This has some performance advantages > over just calling iommu_map iteratively. First, it reduces the > amount of table walking / calculation needed for mapping each page, > given how you know that all the pages will be mapped into a single > virtually-contiguous region (so in most cases, the first-level table > calculation can be reused). Second, it allows one to defer the TLB > (and sometimes cache) maintenance operations until the entire > scatterlist has been mapped, rather than doing a TLB invalidate > after mapping each page, as would have been the case if iommu_map > were just being called from within a loop. Granted, just using > iommu_map many times may be acceptable on the slow path, but I have > seen significant performance gains when using this approach on the > fast path. Yes, from a performance point-of-view that makes sense, as an addition to the existing iommu_map interface. Are the pages in the list allowed to have different page-sizes? Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
