Add the sysfs interface to configure the scheduling domain hierarchy level at which coscheduling should happen for a cgroup. By default, task groups are created with a value of zero corresponding to regular task groups without any coscheduling.
Note, that you cannot specify a value that goes beyond that of the root task group. The value for the root task group cannot be configured via this interface. It has to be configured with a command line argument, which will be added later. The function sdrq_update_root() will be filled in a follow-up commit. Signed-off-by: Jan H. Schönherr <[email protected]> --- kernel/sched/core.c | 44 +++++++++++++++++++++++++++++++++++++++++ kernel/sched/cosched.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++ kernel/sched/sched.h | 4 ++++ 3 files changed, 101 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 75de3b83a8c6..ad2ff9bc535c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6336,6 +6336,9 @@ void sched_offline_group(struct task_group *tg) { unsigned long flags; + /* Don't let offlining/destruction worry about coscheduling aspects */ + cosched_set_scheduled(tg, 0); + /* End participation in shares distribution: */ unregister_fair_sched_group(tg); @@ -6529,7 +6532,33 @@ static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, return (u64) scale_load_down(tg->shares); } +#endif /* CONFIG_FAIR_GROUP_SCHED */ + +#ifdef CONFIG_COSCHEDULING +static int cpu_scheduled_write_u64(struct cgroup_subsys_state *css, struct cftype *cftype, + u64 val) +{ + struct task_group *tg = css_tg(css); + + if (tg == &root_task_group) + return -EACCES; + + if (val > root_task_group.scheduled) + return -EINVAL; + + cosched_set_scheduled(tg, val); + return 0; +} +static u64 cpu_scheduled_read_u64(struct cgroup_subsys_state *css, struct cftype *cft) +{ + struct task_group *tg = css_tg(css); + + return cosched_get_scheduled(tg); +} +#endif /* !CONFIG_COSCHEDULING */ + +#ifdef CONFIG_FAIR_GROUP_SCHED #ifdef CONFIG_CFS_BANDWIDTH static DEFINE_MUTEX(cfs_constraints_mutex); @@ -6825,6 +6854,13 @@ static struct cftype cpu_legacy_files[] = { .write_u64 = cpu_shares_write_u64, }, #endif +#ifdef CONFIG_COSCHEDULING + { + .name = "scheduled", + .read_u64 = cpu_scheduled_read_u64, + .write_u64 = cpu_scheduled_write_u64, + }, +#endif #ifdef CONFIG_CFS_BANDWIDTH { .name = "cfs_quota_us", @@ -7012,6 +7048,14 @@ static struct cftype cpu_files[] = { .write_s64 = cpu_weight_nice_write_s64, }, #endif +#ifdef CONFIG_COSCHEDULING + /* FIXME: This is not conform to cgroup-v2 conventions. */ + { + .name = "scheduled", + .read_u64 = cpu_scheduled_read_u64, + .write_u64 = cpu_scheduled_write_u64, + }, +#endif #ifdef CONFIG_CFS_BANDWIDTH { .name = "max", diff --git a/kernel/sched/cosched.c b/kernel/sched/cosched.c index f2d51079b3db..7c8b8c8d2814 100644 --- a/kernel/sched/cosched.c +++ b/kernel/sched/cosched.c @@ -515,6 +515,59 @@ void cosched_offline_group(struct task_group *tg) list_del_rcu(&cfs->sdrq.tg_siblings); } +static void sdrq_update_root(struct sdrq *sdrq) +{ + /* TBD */ +} + +void cosched_set_scheduled(struct task_group *tg, int level) +{ + struct cfs_rq *cfs_rq; + unsigned long flags; + + raw_spin_lock_irqsave(&tg->lock, flags); + + /* + * Update the is_root-fields of all hierarchical CFS runqueues in this + * task group. To avoid repetitive enqueues and dequeues on every level + * change, we chose pre- or post-order traversal. + */ + if (level > tg->scheduled) { + /* + * roots move upwards: start reconfiguration at the top, so + * that everything is dequeued/enqueued only when we reach + * the previous scheduling level. + */ + tg->scheduled = level; + taskgroup_for_each_cfsrq_topdown(tg, cfs_rq) + sdrq_update_root(&cfs_rq->sdrq); + } + if (level < tg->scheduled) { + /* + * roots move downwards: start reconfiguration at the bottom, + * so that we do the dequeuing/enqueuing immediately, when we + * reach the new scheduling level. + */ + tg->scheduled = level; + taskgroup_for_each_cfsrq(tg, cfs_rq) + sdrq_update_root(&cfs_rq->sdrq); + } + + raw_spin_unlock_irqrestore(&tg->lock, flags); +} + +int cosched_get_scheduled(struct task_group *tg) +{ + unsigned long flags; + int level; + + raw_spin_lock_irqsave(&tg->lock, flags); + level = tg->scheduled; + raw_spin_unlock_irqrestore(&tg->lock, flags); + + return level; +} + /***************************************************************************** * Locking related functions *****************************************************************************/ diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index f6146feb7e55..e257451e05a5 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1212,6 +1212,8 @@ void cosched_init_sdrq(struct task_group *tg, struct cfs_rq *cfs, struct cfs_rq *sd_parent, struct cfs_rq *tg_parent); void cosched_online_group(struct task_group *tg); void cosched_offline_group(struct task_group *tg); +void cosched_set_scheduled(struct task_group *tg, int level); +int cosched_get_scheduled(struct task_group *tg); struct rq *rq_lock_owned(struct rq *rq, struct rq_owner_flags *orf); void rq_unlock_owned(struct rq *rq, struct rq_owner_flags *orf); void rq_chain_init(struct rq_chain *rc, struct rq *rq); @@ -1226,6 +1228,8 @@ static inline void cosched_init_sdrq(struct task_group *tg, struct cfs_rq *cfs, struct cfs_rq *tg_parent) { } static inline void cosched_online_group(struct task_group *tg) { } static inline void cosched_offline_group(struct task_group *tg) { } +static inline void cosched_set_scheduled(struct task_group *tg, int level) { } +static inline int cosched_get_scheduled(struct task_group *tg) { return 0; } static inline struct rq *rq_lock_owned(struct rq *rq, struct rq_owner_flags *orf) { return rq; } static inline void rq_unlock_owned(struct rq *rq, struct rq_owner_flags *orf) { } static inline void rq_chain_init(struct rq_chain *rc, struct rq *rq) { } -- 2.9.3.1.gcba166c.dirty
