On Tue, Jul 21, 2020 at 11:19:52AM +0000, jingrui wrote: > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> ; Michal Hocko <mhocko@xxxxxxxxxx>; Vladimir Davydov <vdavydov.dev@xxxxxxxxx> > > Thanks. > > --- > PROBLEM: cgroup cost too much memory when transfer small files to tmpfs. > > keywords: cgroup PERCPU/memory cost too much. > > description: > > We send small files from node-A to node-B tmpfs /tmp directory using sftp. On > node-B the systemd configured with pam on like below. > > cat /etc/pam.d/password-auth | grep systemd > -session optional pam_systemd.so > > So when transfer a file, a systemd session is created, that means a cgroup is > created, then file saved at /tmp will associated with a cgroup object. After > file transferred, session and cgroup-dir will be removed, but the file in /tmp > still associated with the cgroup object. The PERCPU memory in cgroup/css object > cost a lot(about 0.5MB/per-cgroup-object) on 200/cpus machine. CC Roman who had a patch series to free all this extended (percpu) memory upon cgroup deletion: https://lore.kernel.org/patchwork/cover/1050508/ It looks like it never got merged for some reason.
