On Tue 25-08-15 16:23:34, David Rientjes wrote: > On Mon, 24 Aug 2015, Michal Hocko wrote: > > > The current implementation makes me worry. Is the per hstate break down > > really needed? The implementation would be much more easier without it. > > > > Yes, it's needed. It provides a complete picture of what statically > reserved hugepages are in use and we're not going to change the > implementation when it is needed to differentiate between variable hugetlb > page sizes that risk breaking existing userspace parsers. I thought the purpose was to give the amount of hugetlb based resident memory. At least this is what Jörn was asking for AFAIU. /proc/<pid>/status should be as lightweight as possible. The current implementation is quite heavy as already pointed out. So I am really curious whether this is _really_ needed. I haven't heard about a real usecase except for top displaying HRss which doesn't need the break down values. You have brought that up already http://marc.info/?l=linux-mm&m=143941143109335&w=2 and nobody actually asked for it. "I do not mind having it" is not an argument for inclusion especially when the implementation is more costly and touches hot paths. > > If you have 99% of hugetlb pages then your load is rather specific and I > > would argue that /proc/<pid>/smaps (after patch 1) is a much better way to > > get what you want. > > Some distributions change the permissions of smaps, as already stated, for > pretty clear security reasons since it can be used to defeat existing > protection. There's no reason why hugetlb page usage should not be > exported in the same manner and location as memory usage. /proc/<pid>/status provides only per-memory-type break down information (locked, data, stack, etc...). Different hugetlb sizes are still a hugetlb memory. So I am not sure I understand you argument here. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>