On Thu, 24 Aug 2017 10:55:53 +0200 Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > If we assume that the number of VMAs is going to increase over time, > > then doing anything we can do to reduce the overhead of each VMA > > during PSS collection seems like the right way to go, and that means > > outputting an aggregate statistic (to avoid whatever overhead there is > > per line in writing smaps and in reading each line from userspace). > > > > Also, Dan sent me some numbers from his benchmark measuring PSS on > > system_server (the big Android process) using smaps vs smaps_rollup: > > > > using smaps: > > iterations:1000 pid:1163 pss:220023808 > > 0m29.46s real 0m08.28s user 0m20.98s system > > > > using smaps_rollup: > > iterations:1000 pid:1163 pss:220702720 > > 0m04.39s real 0m00.03s user 0m04.31s system > > I would assume we would do all we can to reduce this kernel->user > overhead first before considering a new user visible file. I haven't > seen any attempts except from the low hanging fruid I have tried. It's hard to believe that we'll get anything like a 5x speedup via optimization of the existing code?
