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/
