On Tue, May 2, 2023 at 10:24 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Tue, May 02, 2023 at 10:20:34AM -0700, Suren Baghdasaryan wrote: > > On Thu, Mar 2, 2023 at 5:16 PM Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote: > > > > > > On Thu, Mar 2, 2023 at 5:13 PM Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote: > > > > > > > > Current 500ms min window size for psi triggers limits polling interval > > > > to 50ms to prevent polling threads from using too much cpu bandwidth by > > > > polling too frequently. However the number of cgroups with triggers is > > > > unlimited, so this protection can be defeated by creating multiple > > > > cgroups with psi triggers (triggers in each cgroup are served by a single > > > > "psimon" kernel thread). > > > > Instead of limiting min polling period, which also limits the latency of > > > > psi events, it's better to limit psi trigger creation to authorized users > > > > only, like we do for system-wide psi triggers (/proc/pressure/* files can > > > > be written only by processes with CAP_SYS_RESOURCE capability). This also > > > > makes access rules for cgroup psi files consistent with system-wide ones. > > > > Add a CAP_SYS_RESOURCE capability check for cgroup psi file writers and > > > > remove the psi window min size limitation. > > > > > > > > Suggested-by: Sudarshan Rajagopalan <quic_sudaraja@xxxxxxxxxxx> > > > > Link: https://lore.kernel.org/all/cover.1676067791.git.quic_sudaraja@xxxxxxxxxxx/ > > > > Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> > > > > Acked-by: Michal Hocko <mhocko@xxxxxxxx> > > > > Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> > > > > > > Forgot to change the --to field from Tejun to PeterZ. > > > Peter, just to clarify, this change is targeted for inclusion in your tree. > > > > I think this patch slipped through the cracks. Peter, could you please > > take it into your tree? > > Sorry, yes, got lost. I'll go queue it for post -rc1. No urgency with > this right? Yes, I'll be merging it into Android branches counting on it making upstream later on :) Greg will hate me for that but I'll survive. Thanks!
