On Wed, Jun 07, 2023 at 09:38:35AM +0200, David Hildenbrand wrote: > I don't want to get too involved in this discussion (busy), but I absolutely > agree on the points that were raised at LSF/MM that > > (A) hugetlb is complicated and very special (many things not integrated with > core-mm, so we need special-casing all over the place). [example: what is a > pte?] This is somethign that absolutely does need to get fixed. It's one of the big sources of complexity and confusion around code that is supposed to work with both hugetlb & THP. I understand why hugetlb originally said "everything is a pte", but THP went a different route, and I think hugetlb now needs to follow. Fixing pagewalk.h to not be complete garbage would be a good start. I can elaborate more along these lines if someone's actually going to put in the work to do it. > (B) We added a bunch of complexity in the past that some people considered > very important (and it was not feature frozen, right? ;) ). Looking back, we > might just not have done some of that, or done it differently/cleaner -- > better integrated in the core. (PMD sharing, MAP_PRIVATE, a reservation > mechanism that still requires preallocation because it fails with NUMA/fork, > ...) It'd be nice if people engaged seriously with the efforts to move that functionality into the core. eg mshare. Saying "Oh just share the hugetlb implementation" is not serious engagement, it's an indication you haven't been paying attention to what the needs are. I haven't looked at the hugetlb reservation mechanism in enough detail to be able to understand why people use it, what they actually want, and how it could be done better in the core. Maybe somebody else could do that.
