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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 <tj@kernel.org>
Reviewed-by: David Vernet <dvernet@meta.com>
Acked-by: Josh Don <joshdon@google.com>
Acked-by: Hao Luo <haoluo@google.com>
Acked-by: Barret Rhoden <brho@google.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Andrea Righi <andrea.righi@canonical.com>
92 lines
3.4 KiB
C
92 lines
3.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* BPF extensible scheduler class: Documentation/scheduler/sched-ext.rst
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*
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* Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
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* Copyright (c) 2022 Tejun Heo <tj@kernel.org>
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* Copyright (c) 2022 David Vernet <dvernet@meta.com>
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*/
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#ifdef CONFIG_SCHED_CLASS_EXT
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void scx_tick(struct rq *rq);
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void init_scx_entity(struct sched_ext_entity *scx);
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void scx_pre_fork(struct task_struct *p);
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int scx_fork(struct task_struct *p);
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void scx_post_fork(struct task_struct *p);
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void scx_cancel_fork(struct task_struct *p);
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bool scx_can_stop_tick(struct rq *rq);
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void scx_rq_activate(struct rq *rq);
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void scx_rq_deactivate(struct rq *rq);
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int scx_check_setscheduler(struct task_struct *p, int policy);
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bool task_should_scx(struct task_struct *p);
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void init_sched_ext_class(void);
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static inline u32 scx_cpuperf_target(s32 cpu)
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{
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if (scx_enabled())
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return cpu_rq(cpu)->scx.cpuperf_target;
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else
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return 0;
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}
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static inline bool task_on_scx(const struct task_struct *p)
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{
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return scx_enabled() && p->sched_class == &ext_sched_class;
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}
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#ifdef CONFIG_SCHED_CORE
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bool scx_prio_less(const struct task_struct *a, const struct task_struct *b,
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bool in_fi);
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#endif
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#else /* CONFIG_SCHED_CLASS_EXT */
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static inline void scx_tick(struct rq *rq) {}
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static inline void scx_pre_fork(struct task_struct *p) {}
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static inline int scx_fork(struct task_struct *p) { return 0; }
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static inline void scx_post_fork(struct task_struct *p) {}
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static inline void scx_cancel_fork(struct task_struct *p) {}
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static inline u32 scx_cpuperf_target(s32 cpu) { return 0; }
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static inline bool scx_can_stop_tick(struct rq *rq) { return true; }
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static inline void scx_rq_activate(struct rq *rq) {}
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static inline void scx_rq_deactivate(struct rq *rq) {}
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static inline int scx_check_setscheduler(struct task_struct *p, int policy) { return 0; }
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static inline bool task_on_scx(const struct task_struct *p) { return false; }
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static inline void init_sched_ext_class(void) {}
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#endif /* CONFIG_SCHED_CLASS_EXT */
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#if defined(CONFIG_SCHED_CLASS_EXT) && defined(CONFIG_SMP)
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void __scx_update_idle(struct rq *rq, bool idle);
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static inline void scx_update_idle(struct rq *rq, bool idle)
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{
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if (scx_enabled())
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__scx_update_idle(rq, idle);
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}
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#else
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static inline void scx_update_idle(struct rq *rq, bool idle) {}
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#endif
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#ifdef CONFIG_CGROUP_SCHED
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#ifdef CONFIG_EXT_GROUP_SCHED
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int scx_tg_online(struct task_group *tg);
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void scx_tg_offline(struct task_group *tg);
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int scx_cgroup_can_attach(struct cgroup_taskset *tset);
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void scx_move_task(struct task_struct *p);
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void scx_cgroup_finish_attach(void);
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void scx_cgroup_cancel_attach(struct cgroup_taskset *tset);
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void scx_group_set_weight(struct task_group *tg, unsigned long cgrp_weight);
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void scx_group_set_idle(struct task_group *tg, bool idle);
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#else /* CONFIG_EXT_GROUP_SCHED */
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static inline int scx_tg_online(struct task_group *tg) { return 0; }
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static inline void scx_tg_offline(struct task_group *tg) {}
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static inline int scx_cgroup_can_attach(struct cgroup_taskset *tset) { return 0; }
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static inline void scx_move_task(struct task_struct *p) {}
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static inline void scx_cgroup_finish_attach(void) {}
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static inline void scx_cgroup_cancel_attach(struct cgroup_taskset *tset) {}
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static inline void scx_group_set_weight(struct task_group *tg, unsigned long cgrp_weight) {}
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static inline void scx_group_set_idle(struct task_group *tg, bool idle) {}
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#endif /* CONFIG_EXT_GROUP_SCHED */
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#endif /* CONFIG_CGROUP_SCHED */
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