On 10/26/2017 07:16 AM, Michal Hocko wrote: >> 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? Actually, I don't remember whether it was tooling or just confused humans. I *think* Dan was trying to write test cases for huge page DAX support and couldn't figure out whether or not it was using large pages. >> 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. We just have to be careful not to cram use-cases into the existing fields which might make them meaningless. I fear that Fan Du's latest patches do that. -- 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
