On Wed 25-10-17 10:14:34, Dave Hansen wrote: > On 10/25/2017 02:30 AM, Michal Hocko wrote: > >> > >> 7f6c17800000-7f6c17e00000 rw-s 00000000 00:06 20559 /dev/dax12.0 > >> Size: 6144 kB > >> . > >> . > >> . > >> Ptes@2MB: 6144 kB > > This says how but it doesn't tell why and who is going to use the > > information and what for. > > The original motivation was for DAX. They have parallel large page > infrastructure separate from hugetlbfs and THP. Their constraints about > when they can use large pages differ from the normal mm cases, so it is > hard to tell when large pages are in use. For instance, the file on > *disk* has to be 2MB contiguous and aligned to map with 2MB pages even > if the mmap() address is >2MB and 2MB-aligned. I assume there is some tool which is going to use this information? > But, in general, this seems like the thing that we probably should have > done in the first place for THP. It's a lot more generic and does not > require someone reading the file to know what the particular > architecture's page sizes are. I fully agree. This just shows how single usecase focus driven smaps file was. That is why I am asking about usecases when somebody want to try yet another special field there. Smaps has become a dump of of special cases which is not really easy to understand and so people tend to use it incorrectly. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
