> On Jul 31, 2019, at 1:25 AM, William Kucharski <william.kucharski@xxxxxxxxxx> wrote: > > This set of patches is the first step towards a mechanism for automatically > mapping read-only text areas of appropriate size and alignment to THPs > whenever possible. > > For now, the central routine, filemap_huge_fault(), amd various support > routines are only included if the experimental kernel configuration option > > RO_EXEC_FILEMAP_HUGE_FAULT_THP > > is enabled. > > This is because filemap_huge_fault() is dependent upon the > address_space_operations vector readpage() pointing to a routine that will > read and fill an entire large page at a time without poulluting the page > cache with PAGESIZE entries for the large page being mapped or performing > readahead that would pollute the page cache entries for succeeding large > pages. Unfortunately, there is no good way to determine how many bytes > were read by readpage(). At present, if filemap_huge_fault() were to call > a conventional readpage() routine, it would only fill the first PAGESIZE > bytes of the large page, which is definitely NOT the desired behavior. > > However, by making the code available now it is hoped that filesystem > maintainers who have pledged to provide such a mechanism will do so more > rapidly. Could you please explain how to test/try this? Would it automatically map all executables to THPs? Thanks, Song
