> On May 17, 2018, at 1:57 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > [CCing Kirill and fs-devel] > > On Mon 14-05-18 07:12:13, William Kucharski wrote: >> One of the downsides of THP as currently implemented is that it only supports >> large page mappings for anonymous pages. > > There is a support for shmem merged already. ext4 was next on the plan > AFAIR but I haven't seen any patches and Kirill was busy with other > stuff IIRC. I couldn't find anything that would specifically map text pages with large pages, so perhaps this could be integrated with that or I may have simply missed changes that would ultimately provide that functionality. > >> I embarked upon this prototype on the theory that it would be advantageous to >> be able to map large ranges of read-only text pages using THP as well. > > Can the fs really support THP only for read mappings? What if those > pages are to be shared in a writable mapping as well? In other words > can this all work without a full THP support for a particular fs? The integration with the page cache would indeed require filesystem support. The end result I'd like to see is full R/W support for large THP pages; I thought the RO text mapping proof of concept worthwhile to see what kind of results we might see and what the thoughts of the community were. Thanks for the feedback. -- Bill
