On 23/07/2015 09:12, Thomas Monjalon wrote: > 2015-07-23 08:34, Gonzalez Monroy, Sergio: >> On 22/07/2015 11:40, Thomas Monjalon wrote: >>> Sergio, >>> >>> As the maintainer of memory allocation, would you consider using >>> libhugetlbfs in DPDK for Linux? >>> It may simplify a part of our memory allocator and avoid some potential >>> bugs which would be already fixed in the dedicated lib. >> I did have a look at it a couple of months ago and I thought there were >> a few issues: >> - get_hugepage_region/get_huge_pages only allocates default size huge pages >> (you can set a different default huge page size with environment >> variables but no >> support for multiple sizes) plus we have no guarantee on physically >> contiguous pages. > Speaking about that, we don't always need contiguous pages. > Maybe we should take it into account when reserving memory. > Some flags DMA (locked physical pages that are not swappable) and CONTIGUOUS > may be considered. Sure. I think I also mentioned this as possible future work in the Dynamic Memzones RFC. >> - That leave us with >> hugetlbfs_unlinked_fd/hugetlbfs_unlinked_fd_for_size. These APIs >> wouldn't simplify a lot the current code, just the allocation of the >> pages themselves >> (ie. creating a file in hugetlbfs mount). >> Then there is the issue with multi-process; because they return a >> file descriptor while >> unlinking the file, we would need some sort of Inter-Process >> Communication to pass >> the descriptors to secondary processes. >> - Not a big deal but AFAIK it is not possible to have multiple mount >> points for the same >> hugepage size, and even if you do, hugetlbfs_find_path_for_size >> returns always the >> same path (ie. first found in list). >> - We still need to parse /proc/self/pagemap to get physical address of >> mapped hugepages. >> >> I guess that if we were to push for a new API such as >> hugetlbfs_fd_for_size, we could use >> it for the hugepage allocation, but we still would have to parse >> /proc/self/pagemap to get >> physical address and then order those hugepages. >> >> Thoughts? > Why not extending the API and pushing our code to this lib? > It would allow to share the maintenance. > > The same move could be done to libpciaccess. I don't disagree with the idea of using libhugetlbfs, I just tried to point out that it's not just a drop in replacement.
Sergio
