From 8195136669661fdfe54e9a8923c33b31c92fc1da Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 4 Sep 2024 10:24:59 -1000 Subject: sched_ext: Add cgroup support Add sched_ext_ops operations to init/exit cgroups, and track task migrations and config changes. A BPF scheduler may not implement or implement only subset of cgroup features. The implemented features can be indicated using %SCX_OPS_HAS_CGOUP_* flags. If cgroup configuration makes use of features that are not implemented, a warning is triggered. While a BPF scheduler is being enabled and disabled, relevant cgroup operations are locked out using scx_cgroup_rwsem. This avoids situations like task prep taking place while the task is being moved across cgroups, making things easier for BPF schedulers. v7: - cgroup interface file visibility toggling is dropped in favor just warning messages. Dynamically changing interface visiblity caused more confusion than helping. v6: - Updated to reflect the removal of SCX_KF_SLEEPABLE. - Updated to use CONFIG_GROUP_SCHED_WEIGHT and fixes for !CONFIG_FAIR_GROUP_SCHED && CONFIG_EXT_GROUP_SCHED. v5: - Flipped the locking order between scx_cgroup_rwsem and cpus_read_lock() to avoid locking order conflict w/ cpuset. Better documentation around locking. - sched_move_task() takes an early exit if the source and destination are identical. This triggered the warning in scx_cgroup_can_attach() as it left p->scx.cgrp_moving_from uncleared. Updated the cgroup migration path so that ops.cgroup_prep_move() is skipped for identity migrations so that its invocations always match ops.cgroup_move() one-to-one. v4: - Example schedulers moved into their own patches. - Fix build failure when !CONFIG_CGROUP_SCHED, reported by Andrea Righi. v3: - Make scx_example_pair switch all tasks by default. - Convert to BPF inline iterators. - scx_bpf_task_cgroup() is added to determine the current cgroup from CPU controller's POV. This allows BPF schedulers to accurately track CPU cgroup membership. - scx_example_flatcg added. This demonstrates flattened hierarchy implementation of CPU cgroup control and shows significant performance improvement when cgroups which are nested multiple levels are under competition. v2: - Build fixes for different CONFIG combinations. Signed-off-by: Tejun Heo Reviewed-by: David Vernet Acked-by: Josh Don Acked-by: Hao Luo Acked-by: Barret Rhoden Reported-by: kernel test robot Cc: Andrea Righi --- include/linux/sched/ext.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h index db2a266113ac..dc646cca4fcf 100644 --- a/include/linux/sched/ext.h +++ b/include/linux/sched/ext.h @@ -188,6 +188,9 @@ struct sched_ext_entity { bool disallow; /* reject switching into SCX */ /* cold fields */ +#ifdef CONFIG_EXT_GROUP_SCHED + struct cgroup *cgrp_moving_from; +#endif /* must be the last field, see init_scx_entity() */ struct list_head tasks_node; }; -- cgit v1.2.3