sched: mix tasks and groups

[mv-sheeva.git] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index 62830eaec52fd7f304359bc2680f2aee45fd0481..1b7399dfa361ee64b183b9985a4ba4abdad51142 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -273,6 +273,7 @@ struct task_group {
        struct list_head list;
 };
 
+#ifdef CONFIG_USER_SCHED
 #ifdef CONFIG_FAIR_GROUP_SCHED
 /* Default task group's sched entity on each cpu */
 static DEFINE_PER_CPU(struct sched_entity, init_sched_entity);
@@ -284,6 +285,7 @@ static DEFINE_PER_CPU(struct cfs_rq, init_cfs_rq) ____cacheline_aligned_in_smp;
 static DEFINE_PER_CPU(struct sched_rt_entity, init_sched_rt_entity);
 static DEFINE_PER_CPU(struct rt_rq, init_rt_rq) ____cacheline_aligned_in_smp;
 #endif
+#endif
 
 /* task_group_lock serializes add/remove of task groups and also changes to
  * a task group's cpu shares.
@@ -7447,6 +7449,10 @@ static void init_tg_cfs_entry(struct rq *rq, struct task_group *tg,
                list_add(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
 
        tg->se[cpu] = se;
+       /* se could be NULL for init_task_group */
+       if (!se)
+               return;
+
        se->cfs_rq = &rq->cfs;
        se->my_q = cfs_rq;
        se->load.weight = tg->shares;
@@ -7469,6 +7475,9 @@ static void init_tg_rt_entry(struct rq *rq, struct task_group *tg,
                list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
 
        tg->rt_se[cpu] = rt_se;
+       if (!rt_se)
+               return;
+
        rt_se->rt_rq = &rq->rt;
        rt_se->my_q = rt_rq;
        rt_se->parent = NULL;
@@ -7539,18 +7548,56 @@ void __init sched_init(void)
 #ifdef CONFIG_FAIR_GROUP_SCHED
                init_task_group.shares = init_task_group_load;
                INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
+#ifdef CONFIG_CGROUP_SCHED
+               /*
+                * How much cpu bandwidth does init_task_group get?
+                *
+                * In case of task-groups formed thr' the cgroup filesystem, it
+                * gets 100% of the cpu resources in the system. This overall
+                * system cpu resource is divided among the tasks of
+                * init_task_group and its child task-groups in a fair manner,
+                * based on each entity's (task or task-group's) weight
+                * (se->load.weight).
+                *
+                * In other words, if init_task_group has 10 tasks of weight
+                * 1024) and two child groups A0 and A1 (of weight 1024 each),
+                * then A0's share of the cpu resource is:
+                *
+                *      A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
+                *
+                * 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);
+#elif defined CONFIG_USER_SCHED
+               /*
+                * In case of task-groups formed thr' the user id of tasks,
+                * init_task_group represents tasks belonging to root user.
+                * Hence it forms a sibling of all subsequent groups formed.
+                * In this case, init_task_group gets only a fraction of overall
+                * system cpu resource, based on the weight assigned to root
+                * user's cpu share (INIT_TASK_GROUP_LOAD). This is accomplished
+                * by letting tasks of init_task_group sit in a separate cfs_rq
+                * (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,
                                &per_cpu(init_cfs_rq, i),
                                &per_cpu(init_sched_entity, i), i, 1);
 
 #endif
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+               rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
 #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);
+#elif defined CONFIG_USER_SCHED
                init_tg_rt_entry(rq, &init_task_group,
                                &per_cpu(init_rt_rq, i),
                                &per_cpu(init_sched_rt_entity, i), i, 1);
-#else
-               rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
+#endif
 #endif
 
                for (j = 0; j < CPU_LOAD_IDX_MAX; j++)