Messages in this thread | | | From | Yosry Ahmed <> | Date | Mon, 6 Feb 2023 14:39:17 -0800 | Subject | Re: [PATCH 14/19] mm: Introduce a cgroup for pinned memory |
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On Mon, Feb 6, 2023 at 2:36 PM Tejun Heo <tj@kernel.org> wrote: > > On Mon, Feb 06, 2023 at 02:32:10PM -0800, Yosry Ahmed wrote: > > I guess it boils down to which we want: > > (a) Limit the amount of memory processes in a cgroup can be pinned/locked. > > (b) Limit the amount of memory charged to a cgroup that can be pinned/locked. > > > > The proposal is doing (a), I suppose if this was part of memcg it > > would be (b), right? > > > > I am not saying it should be one or the other, I am just making sure > > my understanding is clear. > > I don't quite understand what the distinction would mean in practice. It's > just odd to put locked memory in a separate controller from interface POV.
Assume we have 2 cgroups, A and B. A process in cgroup A creates a tmpfs file and writes to it, so the memory is now charged to cgroup A. Now imagine a process in cgroup B tries to lock this memory. - With (a) the amount of locked memory will count toward's cgroup A's limit, because cgroup A is charged for the memory. - With (b) the amount of locked memory will count toward's cgroup B's limit, because a process in cgroup B is locking the memory.
I agree that it is confusing from an interface POV.
> > Thanks. > > -- > tejun
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