sched: group scheduling, sysfs tunables
Add tunables in sysfs to modify a user's cpu share.
A directory is created in sysfs for each new user in the system.
/sys/kernel/uids/<uid>/cpu_share
Reading this file returns the cpu shares granted for the user.
Writing into this file modifies the cpu share for the user. Only an
administrator is allowed to modify a user's cpu share.
Ex:
# cd /sys/kernel/uids/
# cat 512/cpu_share
1024
# echo 2048 > 512/cpu_share
# cat 512/cpu_share
2048
#
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>
diff --git a/kernel/sched.c b/kernel/sched.c
index a3c3ec8..9ac9989 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -162,6 +162,8 @@
/* runqueue "owned" by this group on each cpu */
struct cfs_rq **cfs_rq;
unsigned long shares;
+ /* spinlock to serialize modification to shares */
+ spinlock_t lock;
};
/* Default task group's sched entity on each cpu */
@@ -6533,6 +6535,7 @@
se->parent = NULL;
}
init_task_group.shares = init_task_group_load;
+ spin_lock_init(&init_task_group.lock);
#endif
for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
@@ -6777,6 +6780,7 @@
}
tg->shares = NICE_0_LOAD;
+ spin_lock_init(&tg->lock);
return tg;
@@ -6897,8 +6901,9 @@
{
int i;
+ spin_lock(&tg->lock);
if (tg->shares == shares)
- return 0;
+ goto done;
/* return -EINVAL if the new value is not sane */
@@ -6906,7 +6911,14 @@
for_each_possible_cpu(i)
set_se_shares(tg->se[i], shares);
+done:
+ spin_unlock(&tg->lock);
return 0;
}
+unsigned long sched_group_shares(struct task_group *tg)
+{
+ return tg->shares;
+}
+
#endif /* CONFIG_FAIR_GROUP_SCHED */