On Mon, Oct 12, 2020 at 5:07 PM Michal Hocko <mhocko@xxxxxxxx> wrote: > On Mon 12-10-20 13:49:40, Jann Horn wrote: > > Since 34e55232e59f7b19050267a05ff1226e5cd122a5 (introduced back in > > v2.6.34), Linux uses per-thread RSS counters to reduce cache contention on > > the per-mm counters. With a 4K page size, that means that you can end up > > with the counters off by up to 252KiB per thread. > > Do we actually have any strong case to keep this exception to the > accounting? I have no clue. The concept of "concurrently modified cache lines are bad" seemed vaguely reasonable to me... but I have no idea how much impact this actually has on massively multithreaded processes.
