sched: add fair-user scheduler
Enable user-id based fair group scheduling. This is useful for anyone
who wants to test the group scheduler w/o having to enable
CONFIG_CGROUPS.
A separate scheduling group (i.e struct task_grp) is automatically created for
every new user added to the system. Upon uid change for a task, it is made to
move to the corresponding scheduling group.
A /proc tunable (/proc/root_user_share) is also provided to tune root
user's quota of cpu bandwidth.
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>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/user.c b/kernel/user.c
index 9ca2848..c6387fa 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -50,8 +50,41 @@
.uid_keyring = &root_user_keyring,
.session_keyring = &root_session_keyring,
#endif
+#ifdef CONFIG_FAIR_USER_SCHED
+ .tg = &init_task_grp,
+#endif
};
+#ifdef CONFIG_FAIR_USER_SCHED
+static void sched_destroy_user(struct user_struct *up)
+{
+ sched_destroy_group(up->tg);
+}
+
+static int sched_create_user(struct user_struct *up)
+{
+ int rc = 0;
+
+ up->tg = sched_create_group();
+ if (IS_ERR(up->tg))
+ rc = -ENOMEM;
+
+ return rc;
+}
+
+static void sched_switch_user(struct task_struct *p)
+{
+ sched_move_task(p);
+}
+
+#else /* CONFIG_FAIR_USER_SCHED */
+
+static void sched_destroy_user(struct user_struct *up) { }
+static int sched_create_user(struct user_struct *up) { return 0; }
+static void sched_switch_user(struct task_struct *p) { }
+
+#endif /* CONFIG_FAIR_USER_SCHED */
+
/*
* These routines must be called with the uidhash spinlock held!
*/
@@ -109,6 +142,7 @@
if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
uid_hash_remove(up);
spin_unlock_irqrestore(&uidhash_lock, flags);
+ sched_destroy_user(up);
key_put(up->uid_keyring);
key_put(up->session_keyring);
kmem_cache_free(uid_cachep, up);
@@ -150,6 +184,13 @@
return NULL;
}
+ if (sched_create_user(new) < 0) {
+ key_put(new->uid_keyring);
+ key_put(new->session_keyring);
+ kmem_cache_free(uid_cachep, new);
+ return NULL;
+ }
+
/*
* Before adding this, check whether we raced
* on adding the same user already..
@@ -157,6 +198,7 @@
spin_lock_irq(&uidhash_lock);
up = uid_hash_find(uid, hashent);
if (up) {
+ sched_destroy_user(new);
key_put(new->uid_keyring);
key_put(new->session_keyring);
kmem_cache_free(uid_cachep, new);
@@ -184,6 +226,7 @@
atomic_dec(&old_user->processes);
switch_uid_keyring(new_user);
current->user = new_user;
+ sched_switch_user(current);
/*
* We need to synchronize with __sigqueue_alloc()