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/sched_debug.c b/kernel/sched_debug.c
index 3e47e87..57ee9d5 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -212,6 +212,49 @@
sched_debug_show(NULL, NULL);
}
+#ifdef CONFIG_FAIR_USER_SCHED
+
+static DEFINE_MUTEX(root_user_share_mutex);
+
+static int
+root_user_share_read_proc(char *page, char **start, off_t off, int count,
+ int *eof, void *data)
+{
+ int len;
+
+ len = sprintf(page, "%d\n", init_task_grp_load);
+
+ return len;
+}
+
+static int
+root_user_share_write_proc(struct file *file, const char __user *buffer,
+ unsigned long count, void *data)
+{
+ unsigned long shares;
+ char kbuf[sizeof(unsigned long)+1];
+ int rc = 0;
+
+ if (copy_from_user(kbuf, buffer, sizeof(kbuf)))
+ return -EFAULT;
+
+ shares = simple_strtoul(kbuf, NULL, 0);
+
+ if (!shares)
+ shares = NICE_0_LOAD;
+
+ mutex_lock(&root_user_share_mutex);
+
+ init_task_grp_load = shares;
+ rc = sched_group_set_shares(&init_task_grp, shares);
+
+ mutex_unlock(&root_user_share_mutex);
+
+ return (rc < 0 ? rc : count);
+}
+
+#endif /* CONFIG_FAIR_USER_SCHED */
+
static int sched_debug_open(struct inode *inode, struct file *filp)
{
return single_open(filp, sched_debug_show, NULL);
@@ -234,6 +277,15 @@
pe->proc_fops = &sched_debug_fops;
+#ifdef CONFIG_FAIR_USER_SCHED
+ pe = create_proc_entry("root_user_share", 0644, NULL);
+ if (!pe)
+ return -ENOMEM;
+
+ pe->read_proc = root_user_share_read_proc;
+ pe->write_proc = root_user_share_write_proc;
+#endif
+
return 0;
}