On Tue, May 10, 2022 at 12:18:00AM +0000, Yosry Ahmed wrote: > When a cgroup is popped from the rstat updated tree, subsystems rstat > flushers are run through the css_rstat_flush() callback. Also run bpf > flushers for all subsystems that have at least one bpf rstat flusher > attached, and are enabled for this cgroup. > > A list of subsystems that have attached rstat flushers is maintained to > avoid looping through all subsystems for all cpus for every cgroup that > is being popped from the updated tree. Since we introduce a lock here to > protect this list, also use it to protect rstat_flushers lists inside > each subsystem (since they both need to locked together anyway), and get > read of the locks in struct cgroup_subsys_bpf. > > rstat flushers are run for any enabled subsystem that has flushers > attached, even if it does not subscribe to css flushing through > css_rstat_flush(). This gives flexibility for bpf programs to collect > stats for any subsystem, regardless of the implementation changes in the > kernel. Yeah, again, the fact that these things are associated with a speicfic subsystem feels a bit jarring to me. Let's get that resolved first. Thanks. -- tejun
