On Wed, Sep 4, 2019 at 8:49 AM Thomas Hellström (VMware) <thomas_os@xxxxxxxxxxxx> wrote: > On 9/4/19 1:15 AM, Andy Lutomirski wrote: > > But, reading this, I have more questions: > > > > Can’t you get rid of cvma by using vmf_insert_pfn_prot()? > > It looks like that, although there are comments in the code about > serious performance problems using VM_PFNMAP / vmf_insert_pfn() with > write-combining and PAT, so that would require some serious testing with > hardware I don't have. But I guess there is definitely room for > improvement here. Ideally we'd like to be able to change the > vma->vm_page_prot within fault(). But we can Just a quick comment on this: It's the repeated (per-pfn/pte) lookup of the PAT tables, which are dead slow. If you have a struct io_mapping then that can be done once, and then just blindly inserted. See remap_io_mapping in i915. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel