On Wed, 26 Aug 2015, Michal Hocko wrote: > I thought the purpose was to give the amount of hugetlb based > resident memory.
Persistent hugetlb memory is always resident, the goal is to show what is currently mapped. > 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. > It iterates over HUGE_MAX_HSTATE and reads atomic usage counters twice. On x86, HUGE_MAX_HSTATE == 2. I don't consider that to be expensive. If you are concerned about the memory allocation of struct hugetlb_usage, it could easily be embedded directly in struct mm_struct.
