On Thu, Jun 15, 2023 at 6:59 AM Yu Zhao <yuzhao@xxxxxxxxxx> wrote: > > On Wed, Jun 14, 2023 at 9:48 PM Zhongkun He > <hezhongkun.hzk@xxxxxxxxxxxxx> wrote: > > > > The compressed RAM is currently charged to kernel, not to > > any memory cgroup, which is not satisfy our usage scenario. > > if the memory of a task is limited by memcgroup, it will > > swap out the memory to zram swap device when the memory > > is insufficient. In that case, the memory limit will have > > no effect. > > > > So, it should makes sense to charge the compressed RAM to > > the page's memory cgroup. While looking at this in the past weeks, I believe that there are two distinct problems: 1. Direct zram usage by process within a cg ie. a process writing to a zram device 2. Indirect zram usage by a process within a cg via swap (described above) Both of them probably require different solutions. In order to fix #1, accounting a zram device should be accounted towards a cgroup. IMHO this is something that should be fixed. Yu Zhao and Yosry are probably much more familiar with the solution to #2. WRT per-cgrou-swapfile, to me this is addressing #2, but I agree with Yu Zhao, that there are probably better solutions to this. Lastly, this patchset, while it will possibly not address the swap issue (#2) completely, is it satisfying the needs of #1? - fabian > We used to do this a long time ago, but we had per-memcg swapfiles [1[ > to prevent compressed pages from different memcgs from sharing the > same zspage. > > Does this patchset alone suffer from the same problem, i.e., memcgs > sharing zspages? > > [1] https://lwn.net/Articles/592923/ >
