On Fri, 9 Apr 2021 11:44:16 +0800 Shenming Lu <lushenming@xxxxxxxxxx> wrote: > To optimize for fewer page fault handlings, we can pre-map more pages > than requested at once. > > Note that IOPF_PREMAP_LEN is just an arbitrary value for now, which we > could try further tuning. I'd prefer that the series introduced full end-to-end functionality before trying to improve performance. The pre-map value seems arbitrary here and as noted in the previous patch, the IOMMU API does not guarantee unmaps of ranges smaller than the original mapping. This would need to map with single page granularity in order to guarantee page granularity at the mmu notifier when the IOMMU supports superpages. Thanks, Alex
