sched: group-scheduler core
Add interface to control cpu bandwidth allocation to task-groups.
(not yet configurable, due to missing CONFIG_CONTAINERS)
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
diff --git a/init/Kconfig b/init/Kconfig
index d54d0ca..11c6762 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -281,6 +281,15 @@
Say N if unsure.
+config FAIR_GROUP_SCHED
+ bool "Fair group scheduler"
+ depends on EXPERIMENTAL && CONTAINERS
+ help
+ This option enables you to group tasks and control CPU resource
+ allocation to such groups.
+
+ Say N if unsure.
+
config SYSFS_DEPRECATED
bool "Create deprecated sysfs files"
default y
diff --git a/kernel/sched.c b/kernel/sched.c
index 4ad789d..b2688ce 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -171,6 +171,58 @@
struct list_head queue[MAX_RT_PRIO];
};
+#ifdef CONFIG_FAIR_GROUP_SCHED
+
+#include <linux/container.h>
+
+struct cfs_rq;
+
+/* task group related information */
+struct task_grp {
+ struct container_subsys_state css;
+ /* schedulable entities of this group on each cpu */
+ struct sched_entity **se;
+ /* runqueue "owned" by this group on each cpu */
+ struct cfs_rq **cfs_rq;
+ unsigned long shares;
+};
+
+/* Default task group's sched entity on each cpu */
+static DEFINE_PER_CPU(struct sched_entity, init_sched_entity);
+/* Default task group's cfs_rq on each cpu */
+static DEFINE_PER_CPU(struct cfs_rq, init_cfs_rq) ____cacheline_aligned_in_smp;
+
+static struct sched_entity *init_sched_entity_p[CONFIG_NR_CPUS];
+static struct cfs_rq *init_cfs_rq_p[CONFIG_NR_CPUS];
+
+/* Default task group.
+ * Every task in system belong to this group at bootup.
+ */
+static struct task_grp init_task_grp = {
+ .se = init_sched_entity_p,
+ .cfs_rq = init_cfs_rq_p,
+ };
+
+/* return group to which a task belongs */
+static inline struct task_grp *task_grp(struct task_struct *p)
+{
+ return container_of(task_subsys_state(p, cpu_subsys_id),
+ struct task_grp, css);
+}
+
+/* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
+static inline void set_task_cfs_rq(struct task_struct *p)
+{
+ p->se.cfs_rq = task_grp(p)->cfs_rq[task_cpu(p)];
+ p->se.parent = task_grp(p)->se[task_cpu(p)];
+}
+
+#else
+
+static inline void set_task_cfs_rq(struct task_struct *p) { }
+
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
/* CFS-related fields in a runqueue */
struct cfs_rq {
struct load_weight load;
@@ -197,6 +249,7 @@
* list is used during load balance.
*/
struct list_head leaf_cfs_rq_list; /* Better name : task_cfs_rq_list? */
+ struct task_grp *tg; /* group that "owns" this runqueue */
#endif
};
@@ -419,18 +472,6 @@
return now;
}
-#ifdef CONFIG_FAIR_GROUP_SCHED
-/* Change a task's ->cfs_rq if it moves across CPUs */
-static inline void set_task_cfs_rq(struct task_struct *p)
-{
- p->se.cfs_rq = &task_rq(p)->cfs;
-}
-#else
-static inline void set_task_cfs_rq(struct task_struct *p)
-{
-}
-#endif
-
#ifndef prepare_arch_switch
# define prepare_arch_switch(next) do { } while (0)
#endif
@@ -970,8 +1011,8 @@
{
#ifdef CONFIG_SMP
task_thread_info(p)->cpu = cpu;
- set_task_cfs_rq(p);
#endif
+ set_task_cfs_rq(p);
}
#ifdef CONFIG_SMP
@@ -3885,8 +3926,11 @@
oldprio = p->prio;
on_rq = p->se.on_rq;
- if (on_rq)
+ if (on_rq) {
dequeue_task(rq, p, 0);
+ if (task_running(rq, p))
+ p->sched_class->put_prev_task(rq, p);
+ }
if (rt_prio(prio))
p->sched_class = &rt_sched_class;
@@ -3905,6 +3949,7 @@
if (task_running(rq, p)) {
if (p->prio > oldprio)
resched_task(rq->curr);
+ p->sched_class->set_curr_task(rq);
} else {
check_preempt_curr(rq, p);
}
@@ -4190,8 +4235,11 @@
}
update_rq_clock(rq);
on_rq = p->se.on_rq;
- if (on_rq)
+ if (on_rq) {
deactivate_task(rq, p, 0);
+ if (task_running(rq, p))
+ p->sched_class->put_prev_task(rq, p);
+ }
oldprio = p->prio;
__setscheduler(rq, p, policy, param->sched_priority);
if (on_rq) {
@@ -4204,6 +4252,7 @@
if (task_running(rq, p)) {
if (p->prio > oldprio)
resched_task(rq->curr);
+ p->sched_class->set_curr_task(rq);
} else {
check_preempt_curr(rq, p);
}
@@ -6444,7 +6493,25 @@
init_cfs_rq(&rq->cfs, rq);
#ifdef CONFIG_FAIR_GROUP_SCHED
INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
- list_add(&rq->cfs.leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
+ {
+ struct cfs_rq *cfs_rq = &per_cpu(init_cfs_rq, i);
+ struct sched_entity *se =
+ &per_cpu(init_sched_entity, i);
+
+ init_cfs_rq_p[i] = cfs_rq;
+ init_cfs_rq(cfs_rq, rq);
+ cfs_rq->tg = &init_task_grp;
+ list_add(&cfs_rq->leaf_cfs_rq_list,
+ &rq->leaf_cfs_rq_list);
+
+ init_sched_entity_p[i] = se;
+ se->cfs_rq = &rq->cfs;
+ se->my_q = cfs_rq;
+ se->load.weight = NICE_0_LOAD;
+ se->load.inv_weight = div64_64(1ULL<<32, NICE_0_LOAD);
+ se->parent = NULL;
+ }
+ init_task_grp.shares = NICE_0_LOAD;
#endif
for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
@@ -6632,3 +6699,250 @@
}
#endif
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+
+/* return corresponding task_grp object of a container */
+static inline struct task_grp *container_tg(struct container *cont)
+{
+ return container_of(container_subsys_state(cont, cpu_subsys_id),
+ struct task_grp, css);
+}
+
+/* allocate runqueue etc for a new task group */
+static struct container_subsys_state *
+sched_create_group(struct container_subsys *ss, struct container *cont)
+{
+ struct task_grp *tg;
+ struct cfs_rq *cfs_rq;
+ struct sched_entity *se;
+ int i;
+
+ if (!cont->parent) {
+ /* This is early initialization for the top container */
+ init_task_grp.css.container = cont;
+ return &init_task_grp.css;
+ }
+
+ /* we support only 1-level deep hierarchical scheduler atm */
+ if (cont->parent->parent)
+ return ERR_PTR(-EINVAL);
+
+ tg = kzalloc(sizeof(*tg), GFP_KERNEL);
+ if (!tg)
+ return ERR_PTR(-ENOMEM);
+
+ tg->cfs_rq = kzalloc(sizeof(cfs_rq) * num_possible_cpus(), GFP_KERNEL);
+ if (!tg->cfs_rq)
+ goto err;
+ tg->se = kzalloc(sizeof(se) * num_possible_cpus(), GFP_KERNEL);
+ if (!tg->se)
+ goto err;
+
+ for_each_possible_cpu(i) {
+ struct rq *rq = cpu_rq(i);
+
+ cfs_rq = kmalloc_node(sizeof(struct cfs_rq), GFP_KERNEL,
+ cpu_to_node(i));
+ if (!cfs_rq)
+ goto err;
+
+ se = kmalloc_node(sizeof(struct sched_entity), GFP_KERNEL,
+ cpu_to_node(i));
+ if (!se)
+ goto err;
+
+ memset(cfs_rq, 0, sizeof(struct cfs_rq));
+ memset(se, 0, sizeof(struct sched_entity));
+
+ tg->cfs_rq[i] = cfs_rq;
+ init_cfs_rq(cfs_rq, rq);
+ cfs_rq->tg = tg;
+ list_add_rcu(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
+
+ tg->se[i] = se;
+ se->cfs_rq = &rq->cfs;
+ se->my_q = cfs_rq;
+ se->load.weight = NICE_0_LOAD;
+ se->load.inv_weight = div64_64(1ULL<<32, NICE_0_LOAD);
+ se->parent = NULL;
+ }
+
+ tg->shares = NICE_0_LOAD;
+
+ /* Bind the container to task_grp object we just created */
+ tg->css.container = cont;
+
+ return &tg->css;
+
+err:
+ for_each_possible_cpu(i) {
+ if (tg->cfs_rq && tg->cfs_rq[i])
+ kfree(tg->cfs_rq[i]);
+ if (tg->se && tg->se[i])
+ kfree(tg->se[i]);
+ }
+ if (tg->cfs_rq)
+ kfree(tg->cfs_rq);
+ if (tg->se)
+ kfree(tg->se);
+ if (tg)
+ kfree(tg);
+
+ return ERR_PTR(-ENOMEM);
+}
+
+
+/* destroy runqueue etc associated with a task group */
+static void sched_destroy_group(struct container_subsys *ss,
+ struct container *cont)
+{
+ struct task_grp *tg = container_tg(cont);
+ struct cfs_rq *cfs_rq;
+ struct sched_entity *se;
+ int i;
+
+ for_each_possible_cpu(i) {
+ cfs_rq = tg->cfs_rq[i];
+ list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
+ }
+
+ /* wait for possible concurrent references to cfs_rqs complete */
+ synchronize_sched();
+
+ /* now it should be safe to free those cfs_rqs */
+ for_each_possible_cpu(i) {
+ cfs_rq = tg->cfs_rq[i];
+ kfree(cfs_rq);
+
+ se = tg->se[i];
+ kfree(se);
+ }
+
+ kfree(tg->cfs_rq);
+ kfree(tg->se);
+ kfree(tg);
+}
+
+static int sched_can_attach(struct container_subsys *ss,
+ struct container *cont, struct task_struct *tsk)
+{
+ /* We don't support RT-tasks being in separate groups */
+ if (tsk->sched_class != &fair_sched_class)
+ return -EINVAL;
+
+ return 0;
+}
+
+/* change task's runqueue when it moves between groups */
+static void sched_move_task(struct container_subsys *ss, struct container *cont,
+ struct container *old_cont, struct task_struct *tsk)
+{
+ int on_rq, running;
+ unsigned long flags;
+ struct rq *rq;
+
+ rq = task_rq_lock(tsk, &flags);
+
+ if (tsk->sched_class != &fair_sched_class)
+ goto done;
+
+ update_rq_clock(rq);
+
+ running = task_running(rq, tsk);
+ on_rq = tsk->se.on_rq;
+
+ if (on_rq) {
+ dequeue_task(rq, tsk, 0);
+ if (unlikely(running))
+ tsk->sched_class->put_prev_task(rq, tsk);
+ }
+
+ set_task_cfs_rq(tsk);
+
+ if (on_rq) {
+ enqueue_task(rq, tsk, 0);
+ if (unlikely(running))
+ tsk->sched_class->set_curr_task(rq);
+ }
+
+done:
+ task_rq_unlock(rq, &flags);
+}
+
+static void set_se_shares(struct sched_entity *se, unsigned long shares)
+{
+ struct cfs_rq *cfs_rq = se->cfs_rq;
+ struct rq *rq = cfs_rq->rq;
+ int on_rq;
+
+ spin_lock_irq(&rq->lock);
+
+ on_rq = se->on_rq;
+ if (on_rq)
+ dequeue_entity(cfs_rq, se, 0);
+
+ se->load.weight = shares;
+ se->load.inv_weight = div64_64((1ULL<<32), shares);
+
+ if (on_rq)
+ enqueue_entity(cfs_rq, se, 0);
+
+ spin_unlock_irq(&rq->lock);
+}
+
+static ssize_t cpu_shares_write(struct container *cont, struct cftype *cftype,
+ struct file *file, const char __user *userbuf,
+ size_t nbytes, loff_t *ppos)
+{
+ int i;
+ unsigned long shareval;
+ struct task_grp *tg = container_tg(cont);
+ char buffer[2*sizeof(unsigned long) + 1];
+
+ if (nbytes > 2*sizeof(unsigned long)) /* safety check */
+ return -E2BIG;
+
+ if (copy_from_user(buffer, userbuf, nbytes))
+ return -EFAULT;
+
+ buffer[nbytes] = 0; /* nul-terminate */
+ shareval = simple_strtoul(buffer, NULL, 10);
+
+ tg->shares = shareval;
+ for_each_possible_cpu(i)
+ set_se_shares(tg->se[i], shareval);
+
+ return nbytes;
+}
+
+static u64 cpu_shares_read_uint(struct container *cont, struct cftype *cft)
+{
+ struct task_grp *tg = container_tg(cont);
+
+ return (u64) tg->shares;
+}
+
+struct cftype cpuctl_share = {
+ .name = "shares",
+ .read_uint = cpu_shares_read_uint,
+ .write = cpu_shares_write,
+};
+
+static int sched_populate(struct container_subsys *ss, struct container *cont)
+{
+ return container_add_file(cont, ss, &cpuctl_share);
+}
+
+struct container_subsys cpu_subsys = {
+ .name = "cpu",
+ .create = sched_create_group,
+ .destroy = sched_destroy_group,
+ .can_attach = sched_can_attach,
+ .attach = sched_move_task,
+ .populate = sched_populate,
+ .subsys_id = cpu_subsys_id,
+ .early_init = 1,
+};
+
+#endif /* CONFIG_FAIR_GROUP_SCHED */
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ec445ca..12ab933 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -610,8 +610,7 @@
*/
static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
{
- /* A later patch will take group into account */
- return &cpu_rq(this_cpu)->cfs;
+ return cfs_rq->tg->cfs_rq[this_cpu];
}
/* Iterate thr' all leaf cfs_rq's on a runqueue */
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index 3503fb2..5ebf829 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -50,6 +50,10 @@
{
}
+static void set_curr_task_idle(struct rq *rq)
+{
+}
+
/*
* Simple, special scheduling class for the per-CPU idle tasks:
*/
@@ -66,6 +70,7 @@
.load_balance = load_balance_idle,
+ .set_curr_task = set_curr_task_idle,
.task_tick = task_tick_idle,
/* no .task_new for idle tasks */
};
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 4b87476..45b339f 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -218,6 +218,10 @@
}
}
+static void set_curr_task_rt(struct rq *rq)
+{
+}
+
static struct sched_class rt_sched_class __read_mostly = {
.enqueue_task = enqueue_task_rt,
.dequeue_task = dequeue_task_rt,
@@ -230,5 +234,6 @@
.load_balance = load_balance_rt,
+ .set_curr_task = set_curr_task_rt,
.task_tick = task_tick_rt,
};
