sched: allow the group scheduler to have multiple levels

This patch makes the group scheduler multi hierarchy aware.

[a.p.zijlstra@chello.nl: rt-parts and assorted fixes]
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 79c025c3b62744a6f0bfd48c16dda6555dc8092a..fa14781747cb7b5d1c39aaaab259366365cfcf89 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2052,7 +2052,7 @@ extern void normalize_rt_tasks(void);
 
 extern struct task_group init_task_group;
 
-extern struct task_group *sched_create_group(void);
+extern struct task_group *sched_create_group(struct task_group *parent);
 extern void sched_destroy_group(struct task_group *tg);
 extern void sched_move_task(struct task_struct *tsk);
 #ifdef CONFIG_FAIR_GROUP_SCHED

diff --git a/kernel/sched.c b/kernel/sched.c
index 1b7399dfa361ee64b183b9985a4ba4abdad51142..f9c8da798bbf0e844960275cdf8ed4e96811518c 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7438,10 +7438,11 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
 }
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
-static void init_tg_cfs_entry(struct rq *rq, struct task_group *tg,
-               struct cfs_rq *cfs_rq, struct sched_entity *se,
-               int cpu, int add)
+static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
+                               struct sched_entity *se, int cpu, int add,
+                               struct sched_entity *parent)
 {
+       struct rq *rq = cpu_rq(cpu);
        tg->cfs_rq[cpu] = cfs_rq;
        init_cfs_rq(cfs_rq, rq);
        cfs_rq->tg = tg;
@@ -7453,19 +7454,25 @@ static void init_tg_cfs_entry(struct rq *rq, struct task_group *tg,
        if (!se)
                return;
 
-       se->cfs_rq = &rq->cfs;
+       if (!parent)
+               se->cfs_rq = &rq->cfs;
+       else
+               se->cfs_rq = parent->my_q;
+
        se->my_q = cfs_rq;
        se->load.weight = tg->shares;
        se->load.inv_weight = div64_64(1ULL<<32, se->load.weight);
-       se->parent = NULL;
+       se->parent = parent;
 }
 #endif
 
 #ifdef CONFIG_RT_GROUP_SCHED
-static void init_tg_rt_entry(struct rq *rq, struct task_group *tg,
-               struct rt_rq *rt_rq, struct sched_rt_entity *rt_se,
-               int cpu, int add)
+static void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
+               struct sched_rt_entity *rt_se, int cpu, int add,
+               struct sched_rt_entity *parent)
 {
+       struct rq *rq = cpu_rq(cpu);
+
        tg->rt_rq[cpu] = rt_rq;
        init_rt_rq(rt_rq, rq);
        rt_rq->tg = tg;
@@ -7478,9 +7485,14 @@ static void init_tg_rt_entry(struct rq *rq, struct task_group *tg,
        if (!rt_se)
                return;
 
+       if (!parent)
+               rt_se->rt_rq = &rq->rt;
+       else
+               rt_se->rt_rq = parent->my_q;
+
        rt_se->rt_rq = &rq->rt;
        rt_se->my_q = rt_rq;
-       rt_se->parent = NULL;
+       rt_se->parent = parent;
        INIT_LIST_HEAD(&rt_se->run_list);
 }
 #endif
@@ -7568,7 +7580,7 @@ void __init sched_init(void)
                 * We achieve this by letting init_task_group's tasks sit
                 * directly in rq->cfs (i.e init_task_group->se[] = NULL).
                 */
-               init_tg_cfs_entry(rq, &init_task_group, &rq->cfs, NULL, i, 1);
+               init_tg_cfs_entry(&init_task_group, &rq->cfs, NULL, i, 1, NULL);
 #elif defined CONFIG_USER_SCHED
                /*
                 * In case of task-groups formed thr' the user id of tasks,
@@ -7581,9 +7593,9 @@ void __init sched_init(void)
                 * (init_cfs_rq) and having one entity represent this group of
                 * tasks in rq->cfs (i.e init_task_group->se[] != NULL).
                 */
-               init_tg_cfs_entry(rq, &init_task_group,
+               init_tg_cfs_entry(&init_task_group,
                                &per_cpu(init_cfs_rq, i),
-                               &per_cpu(init_sched_entity, i), i, 1);
+                               &per_cpu(init_sched_entity, i), i, 1, NULL);
 
 #endif
 #endif /* CONFIG_FAIR_GROUP_SCHED */
@@ -7592,11 +7604,11 @@ void __init sched_init(void)
 #ifdef CONFIG_RT_GROUP_SCHED
                INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
 #ifdef CONFIG_CGROUP_SCHED
-               init_tg_rt_entry(rq, &init_task_group, &rq->rt, NULL, i, 1);
+               init_tg_rt_entry(&init_task_group, &rq->rt, NULL, i, 1, NULL);
 #elif defined CONFIG_USER_SCHED
-               init_tg_rt_entry(rq, &init_task_group,
+               init_tg_rt_entry(&init_task_group,
                                &per_cpu(init_rt_rq, i),
-                               &per_cpu(init_sched_rt_entity, i), i, 1);
+                               &per_cpu(init_sched_rt_entity, i), i, 1, NULL);
 #endif
 #endif
 
@@ -7798,10 +7810,11 @@ static void free_fair_sched_group(struct task_group *tg)
        kfree(tg->se);
 }
 
-static int alloc_fair_sched_group(struct task_group *tg)
+static
+int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
 {
        struct cfs_rq *cfs_rq;
-       struct sched_entity *se;
+       struct sched_entity *se, *parent_se;
        struct rq *rq;
        int i;
 
@@ -7827,7 +7840,8 @@ static int alloc_fair_sched_group(struct task_group *tg)
                if (!se)
                        goto err;
 
-               init_tg_cfs_entry(rq, tg, cfs_rq, se, i, 0);
+               parent_se = parent ? parent->se[i] : NULL;
+               init_tg_cfs_entry(tg, cfs_rq, se, i, 0, parent_se);
        }
 
        return 1;
@@ -7851,7 +7865,8 @@ static inline void free_fair_sched_group(struct task_group *tg)
 {
 }
 
-static inline int alloc_fair_sched_group(struct task_group *tg)
+static inline
+int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
 {
        return 1;
 }
@@ -7883,10 +7898,11 @@ static void free_rt_sched_group(struct task_group *tg)
        kfree(tg->rt_se);
 }
 
-static int alloc_rt_sched_group(struct task_group *tg)
+static
+int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
 {
        struct rt_rq *rt_rq;
-       struct sched_rt_entity *rt_se;
+       struct sched_rt_entity *rt_se, *parent_se;
        struct rq *rq;
        int i;
 
@@ -7913,7 +7929,8 @@ static int alloc_rt_sched_group(struct task_group *tg)
                if (!rt_se)
                        goto err;
 
-               init_tg_rt_entry(rq, tg, rt_rq, rt_se, i, 0);
+               parent_se = parent ? parent->rt_se[i] : NULL;
+               init_tg_rt_entry(tg, rt_rq, rt_se, i, 0, parent_se);
        }
 
        return 1;
@@ -7937,7 +7954,8 @@ static inline void free_rt_sched_group(struct task_group *tg)
 {
 }
 
-static inline int alloc_rt_sched_group(struct task_group *tg)
+static inline
+int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
 {
        return 1;
 }
@@ -7960,7 +7978,7 @@ static void free_sched_group(struct task_group *tg)
 }
 
 /* allocate runqueue etc for a new task group */
-struct task_group *sched_create_group(void)
+struct task_group *sched_create_group(struct task_group *parent)
 {
        struct task_group *tg;
        unsigned long flags;
@@ -7970,10 +7988,10 @@ struct task_group *sched_create_group(void)
        if (!tg)
                return ERR_PTR(-ENOMEM);
 
-       if (!alloc_fair_sched_group(tg))
+       if (!alloc_fair_sched_group(tg, parent))
                goto err;
 
-       if (!alloc_rt_sched_group(tg))
+       if (!alloc_rt_sched_group(tg, parent))
                goto err;
 
        spin_lock_irqsave(&task_group_lock, flags);
@@ -8084,6 +8102,12 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
        int i;
        unsigned long flags;
 
+       /*
+        * We can't change the weight of the root cgroup.
+        */
+       if (!tg->se[0])
+               return -EINVAL;
+
        /*
         * A weight of 0 or 1 can cause arithmetics problems.
         * (The default weight is 1024 - so there's no practical
@@ -8327,7 +8351,7 @@ static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
 static struct cgroup_subsys_state *
 cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
 {
-       struct task_group *tg;
+       struct task_group *tg, *parent;
 
        if (!cgrp->parent) {
                /* This is early initialization for the top cgroup */
@@ -8335,11 +8359,8 @@ cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
                return &init_task_group.css;
        }
 
-       /* we support only 1-level deep hierarchical scheduler atm */
-       if (cgrp->parent->parent)
-               return ERR_PTR(-EINVAL);
-
-       tg = sched_create_group();
+       parent = cgroup_tg(cgrp->parent);
+       tg = sched_create_group(parent);
        if (IS_ERR(tg))
                return ERR_PTR(-ENOMEM);
 

diff --git a/kernel/user.c b/kernel/user.c
index 5925c6887c10d629cba6f977c6ea9f3896b48dec..a28d9f992468b8d1736a33c9e75dda1acdc760b0 100644 (file)
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -101,7 +101,7 @@ static int sched_create_user(struct user_struct *up)
 {
        int rc = 0;
 
-       up->tg = sched_create_group();
+       up->tg = sched_create_group(NULL);
        if (IS_ERR(up->tg))
                rc = -ENOMEM;