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>
This commit is contained in:
Dhaval Giani
Ingo Molnar
parent
8ca0e14ffb
commit
5cb350baf5
6 changed files with 317 additions and 87 deletions
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@ -117,3 +117,70 @@ Some implementation details:
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iterators of the scheduling modules are used. The balancing code got
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quite a bit simpler as a result.
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Group scheduler extension to CFS
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================================
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Normally the scheduler operates on individual tasks and strives to provide
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fair CPU time to each task. Sometimes, it may be desirable to group tasks
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and provide fair CPU time to each such task group. For example, it may
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be desirable to first provide fair CPU time to each user on the system
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and then to each task belonging to a user.
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CONFIG_FAIR_GROUP_SCHED strives to achieve exactly that. It lets
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SCHED_NORMAL/BATCH tasks be be grouped and divides CPU time fairly among such
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groups. At present, there are two (mutually exclusive) mechanisms to group
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tasks for CPU bandwidth control purpose:
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- Based on user id (CONFIG_FAIR_USER_SCHED)
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In this option, tasks are grouped according to their user id.
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- Based on "cgroup" pseudo filesystem (CONFIG_FAIR_CGROUP_SCHED)
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This options lets the administrator create arbitrary groups
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of tasks, using the "cgroup" pseudo filesystem. See
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Documentation/cgroups.txt for more information about this
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filesystem.
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Only one of these options to group tasks can be chosen and not both.
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Group scheduler tunables:
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When CONFIG_FAIR_USER_SCHED is defined, a directory is created in sysfs for
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each new user and a "cpu_share" file is added in that directory.
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# cd /sys/kernel/uids
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# cat 512/cpu_share # Display user 512's CPU share
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1024
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# echo 2048 > 512/cpu_share # Modify user 512's CPU share
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# cat 512/cpu_share # Display user 512's CPU share
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2048
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#
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CPU bandwidth between two users are divided in the ratio of their CPU shares.
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For ex: if you would like user "root" to get twice the bandwidth of user
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"guest", then set the cpu_share for both the users such that "root"'s
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cpu_share is twice "guest"'s cpu_share
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When CONFIG_FAIR_CGROUP_SCHED is defined, a "cpu.shares" file is created
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for each group created using the pseudo filesystem. See example steps
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below to create task groups and modify their CPU share using the "cgroups"
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pseudo filesystem
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# mkdir /dev/cpuctl
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# mount -t cgroup -ocpu none /dev/cpuctl
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# cd /dev/cpuctl
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# mkdir multimedia # create "multimedia" group of tasks
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# mkdir browser # create "browser" group of tasks
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# #Configure the multimedia group to receive twice the CPU bandwidth
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# #that of browser group
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# echo 2048 > multimedia/cpu.shares
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# echo 1024 > browser/cpu.shares
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# firefox & # Launch firefox and move it to "browser" group
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# echo <firefox_pid> > browser/tasks
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# #Launch gmplayer (or your favourite movie player)
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# echo <movie_player_pid> > multimedia/tasks
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@ -87,6 +87,7 @@ struct sched_param {
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#include <linux/timer.h>
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#include <linux/hrtimer.h>
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#include <linux/task_io_accounting.h>
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#include <linux/kobject.h>
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#include <asm/processor.h>
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@ -599,9 +600,18 @@ struct user_struct {
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#ifdef CONFIG_FAIR_USER_SCHED
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struct task_group *tg;
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struct kset kset;
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struct subsys_attribute user_attr;
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struct work_struct work;
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#endif
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};
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#ifdef CONFIG_FAIR_USER_SCHED
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extern int uids_kobject_init(void);
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#else
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static inline int uids_kobject_init(void) { return 0; }
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#endif
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extern struct user_struct *find_user(uid_t);
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extern struct user_struct root_user;
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@ -1848,6 +1858,7 @@ extern struct task_group *sched_create_group(void);
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extern void sched_destroy_group(struct task_group *tg);
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extern void sched_move_task(struct task_struct *tsk);
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extern int sched_group_set_shares(struct task_group *tg, unsigned long shares);
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extern unsigned long sched_group_shares(struct task_group *tg);
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#endif
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@ -14,6 +14,7 @@
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/kexec.h>
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#include <linux/sched.h>
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#define KERNEL_ATTR_RO(_name) \
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static struct subsys_attribute _name##_attr = __ATTR_RO(_name)
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@ -116,6 +117,13 @@ static int __init ksysfs_init(void)
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¬es_attr);
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}
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/*
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* Create "/sys/kernel/uids" directory and corresponding root user's
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* directory under it.
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*/
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if (!error)
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error = uids_kobject_init();
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return error;
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}
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@ -162,6 +162,8 @@ struct task_group {
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/* runqueue "owned" by this group on each cpu */
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struct cfs_rq **cfs_rq;
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unsigned long shares;
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/* spinlock to serialize modification to shares */
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spinlock_t lock;
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};
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/* Default task group's sched entity on each cpu */
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@ -6533,6 +6535,7 @@ void __init sched_init(void)
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se->parent = NULL;
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}
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init_task_group.shares = init_task_group_load;
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spin_lock_init(&init_task_group.lock);
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#endif
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for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
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@ -6777,6 +6780,7 @@ struct task_group *sched_create_group(void)
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}
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tg->shares = NICE_0_LOAD;
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spin_lock_init(&tg->lock);
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return tg;
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@ -6897,8 +6901,9 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
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{
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int i;
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spin_lock(&tg->lock);
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if (tg->shares == shares)
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return 0;
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goto done;
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/* return -EINVAL if the new value is not sane */
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@ -6906,7 +6911,14 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
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for_each_possible_cpu(i)
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set_se_shares(tg->se[i], shares);
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done:
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spin_unlock(&tg->lock);
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return 0;
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}
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unsigned long sched_group_shares(struct task_group *tg)
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{
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return tg->shares;
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}
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#endif /* CONFIG_FAIR_GROUP_SCHED */
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@ -231,45 +231,6 @@ static void sysrq_sched_debug_show(void)
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sched_debug_show(NULL, NULL);
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}
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#ifdef CONFIG_FAIR_USER_SCHED
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static DEFINE_MUTEX(root_user_share_mutex);
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static int
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root_user_share_read_proc(char *page, char **start, off_t off, int count,
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int *eof, void *data)
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{
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return sprintf(page, "%d\n", init_task_group_load);
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}
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static int
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root_user_share_write_proc(struct file *file, const char __user *buffer,
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unsigned long count, void *data)
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{
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unsigned long shares;
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char kbuf[sizeof(unsigned long)+1];
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int rc = 0;
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if (copy_from_user(kbuf, buffer, sizeof(kbuf)))
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return -EFAULT;
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shares = simple_strtoul(kbuf, NULL, 0);
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if (!shares)
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shares = NICE_0_LOAD;
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mutex_lock(&root_user_share_mutex);
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init_task_group_load = shares;
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rc = sched_group_set_shares(&init_task_group, shares);
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mutex_unlock(&root_user_share_mutex);
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return (rc < 0 ? rc : count);
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}
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#endif /* CONFIG_FAIR_USER_SCHED */
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static int sched_debug_open(struct inode *inode, struct file *filp)
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{
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return single_open(filp, sched_debug_show, NULL);
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@ -292,15 +253,6 @@ static int __init init_sched_debug_procfs(void)
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pe->proc_fops = &sched_debug_fops;
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#ifdef CONFIG_FAIR_USER_SCHED
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pe = create_proc_entry("root_user_cpu_share", 0644, NULL);
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if (!pe)
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return -ENOMEM;
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pe->read_proc = root_user_share_read_proc;
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pe->write_proc = root_user_share_write_proc;
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#endif
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return 0;
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}
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256
kernel/user.c
256
kernel/user.c
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@ -55,7 +55,41 @@ struct user_struct root_user = {
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#endif
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};
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/*
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* These routines must be called with the uidhash spinlock held!
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*/
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static inline void uid_hash_insert(struct user_struct *up,
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struct hlist_head *hashent)
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{
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hlist_add_head(&up->uidhash_node, hashent);
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}
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static inline void uid_hash_remove(struct user_struct *up)
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{
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hlist_del_init(&up->uidhash_node);
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}
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static inline struct user_struct *uid_hash_find(uid_t uid,
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struct hlist_head *hashent)
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{
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struct user_struct *user;
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struct hlist_node *h;
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hlist_for_each_entry(user, h, hashent, uidhash_node) {
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if (user->uid == uid) {
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atomic_inc(&user->__count);
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return user;
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}
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}
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return NULL;
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}
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#ifdef CONFIG_FAIR_USER_SCHED
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static struct kobject uids_kobject; /* represents /sys/kernel/uids directory */
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static DEFINE_MUTEX(uids_mutex);
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static void sched_destroy_user(struct user_struct *up)
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{
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sched_destroy_group(up->tg);
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@ -77,42 +111,173 @@ static void sched_switch_user(struct task_struct *p)
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sched_move_task(p);
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}
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static inline void uids_mutex_lock(void)
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{
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mutex_lock(&uids_mutex);
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}
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static inline void uids_mutex_unlock(void)
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{
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mutex_unlock(&uids_mutex);
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}
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/* return cpu shares held by the user */
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ssize_t cpu_shares_show(struct kset *kset, char *buffer)
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{
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struct user_struct *up = container_of(kset, struct user_struct, kset);
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return sprintf(buffer, "%lu\n", sched_group_shares(up->tg));
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}
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/* modify cpu shares held by the user */
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ssize_t cpu_shares_store(struct kset *kset, const char *buffer, size_t size)
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{
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struct user_struct *up = container_of(kset, struct user_struct, kset);
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unsigned long shares;
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int rc;
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sscanf(buffer, "%lu", &shares);
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rc = sched_group_set_shares(up->tg, shares);
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return (rc ? rc : size);
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}
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static void user_attr_init(struct subsys_attribute *sa, char *name, int mode)
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{
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sa->attr.name = name;
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sa->attr.mode = mode;
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sa->show = cpu_shares_show;
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sa->store = cpu_shares_store;
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}
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/* Create "/sys/kernel/uids/<uid>" directory and
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* "/sys/kernel/uids/<uid>/cpu_share" file for this user.
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*/
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static int user_kobject_create(struct user_struct *up)
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{
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struct kset *kset = &up->kset;
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struct kobject *kobj = &kset->kobj;
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int error;
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memset(kset, 0, sizeof(struct kset));
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kobj->parent = &uids_kobject; /* create under /sys/kernel/uids dir */
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kobject_set_name(kobj, "%d", up->uid);
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kset_init(kset);
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user_attr_init(&up->user_attr, "cpu_share", 0644);
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error = kobject_add(kobj);
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if (error)
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goto done;
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error = sysfs_create_file(kobj, &up->user_attr.attr);
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if (error)
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kobject_del(kobj);
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done:
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return error;
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}
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/* create these in sysfs filesystem:
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* "/sys/kernel/uids" directory
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* "/sys/kernel/uids/0" directory (for root user)
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* "/sys/kernel/uids/0/cpu_share" file (for root user)
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*/
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int __init uids_kobject_init(void)
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{
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int error;
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/* create under /sys/kernel dir */
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uids_kobject.parent = &kernel_subsys.kobj;
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kobject_set_name(&uids_kobject, "uids");
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kobject_init(&uids_kobject);
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error = kobject_add(&uids_kobject);
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if (!error)
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error = user_kobject_create(&root_user);
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return error;
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}
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/* work function to remove sysfs directory for a user and free up
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* corresponding structures.
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*/
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static void remove_user_sysfs_dir(struct work_struct *w)
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{
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struct user_struct *up = container_of(w, struct user_struct, work);
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struct kobject *kobj = &up->kset.kobj;
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unsigned long flags;
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int remove_user = 0;
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/* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
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* atomic.
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*/
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uids_mutex_lock();
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local_irq_save(flags);
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if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
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uid_hash_remove(up);
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remove_user = 1;
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spin_unlock_irqrestore(&uidhash_lock, flags);
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} else {
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local_irq_restore(flags);
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}
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if (!remove_user)
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goto done;
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sysfs_remove_file(kobj, &up->user_attr.attr);
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kobject_del(kobj);
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sched_destroy_user(up);
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key_put(up->uid_keyring);
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key_put(up->session_keyring);
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kmem_cache_free(uid_cachep, up);
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done:
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uids_mutex_unlock();
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}
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/* IRQs are disabled and uidhash_lock is held upon function entry.
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* IRQ state (as stored in flags) is restored and uidhash_lock released
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* upon function exit.
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*/
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static inline void free_user(struct user_struct *up, unsigned long flags)
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{
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/* restore back the count */
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atomic_inc(&up->__count);
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spin_unlock_irqrestore(&uidhash_lock, flags);
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INIT_WORK(&up->work, remove_user_sysfs_dir);
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schedule_work(&up->work);
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}
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#else /* CONFIG_FAIR_USER_SCHED */
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static void sched_destroy_user(struct user_struct *up) { }
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static int sched_create_user(struct user_struct *up) { return 0; }
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static void sched_switch_user(struct task_struct *p) { }
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static inline int user_kobject_create(struct user_struct *up) { return 0; }
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static inline void uids_mutex_lock(void) { }
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static inline void uids_mutex_unlock(void) { }
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/* IRQs are disabled and uidhash_lock is held upon function entry.
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* IRQ state (as stored in flags) is restored and uidhash_lock released
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* upon function exit.
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*/
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static inline void free_user(struct user_struct *up, unsigned long flags)
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{
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uid_hash_remove(up);
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spin_unlock_irqrestore(&uidhash_lock, flags);
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sched_destroy_user(up);
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key_put(up->uid_keyring);
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key_put(up->session_keyring);
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kmem_cache_free(uid_cachep, up);
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}
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#endif /* CONFIG_FAIR_USER_SCHED */
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/*
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* These routines must be called with the uidhash spinlock held!
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*/
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static inline void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
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{
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hlist_add_head(&up->uidhash_node, hashent);
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}
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static inline void uid_hash_remove(struct user_struct *up)
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{
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hlist_del_init(&up->uidhash_node);
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}
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static inline struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
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{
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struct user_struct *user;
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struct hlist_node *h;
|
||||
|
||||
hlist_for_each_entry(user, h, hashent, uidhash_node) {
|
||||
if(user->uid == uid) {
|
||||
atomic_inc(&user->__count);
|
||||
return user;
|
||||
}
|
||||
}
|
||||
|
||||
return NULL;
|
||||
}
|
||||
|
||||
/*
|
||||
* Locate the user_struct for the passed UID. If found, take a ref on it. The
|
||||
* caller must undo that ref with free_uid().
|
||||
|
|
@ -139,16 +304,10 @@ void free_uid(struct user_struct *up)
|
|||
return;
|
||||
|
||||
local_irq_save(flags);
|
||||
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);
|
||||
} else {
|
||||
if (atomic_dec_and_lock(&up->__count, &uidhash_lock))
|
||||
free_user(up, flags);
|
||||
else
|
||||
local_irq_restore(flags);
|
||||
}
|
||||
}
|
||||
|
||||
struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
|
||||
|
|
@ -156,6 +315,11 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
|
|||
struct hlist_head *hashent = uidhashentry(ns, uid);
|
||||
struct user_struct *up;
|
||||
|
||||
/* Make uid_hash_find() + user_kobject_create() + uid_hash_insert()
|
||||
* atomic.
|
||||
*/
|
||||
uids_mutex_lock();
|
||||
|
||||
spin_lock_irq(&uidhash_lock);
|
||||
up = uid_hash_find(uid, hashent);
|
||||
spin_unlock_irq(&uidhash_lock);
|
||||
|
|
@ -191,6 +355,15 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
|
|||
return NULL;
|
||||
}
|
||||
|
||||
if (user_kobject_create(new)) {
|
||||
sched_destroy_user(new);
|
||||
key_put(new->uid_keyring);
|
||||
key_put(new->session_keyring);
|
||||
kmem_cache_free(uid_cachep, new);
|
||||
uids_mutex_unlock();
|
||||
return NULL;
|
||||
}
|
||||
|
||||
/*
|
||||
* Before adding this, check whether we raced
|
||||
* on adding the same user already..
|
||||
|
|
@ -198,7 +371,11 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
|
|||
spin_lock_irq(&uidhash_lock);
|
||||
up = uid_hash_find(uid, hashent);
|
||||
if (up) {
|
||||
sched_destroy_user(new);
|
||||
/* This case is not possible when CONFIG_FAIR_USER_SCHED
|
||||
* is defined, since we serialize alloc_uid() using
|
||||
* uids_mutex. Hence no need to call
|
||||
* sched_destroy_user() or remove_user_sysfs_dir().
|
||||
*/
|
||||
key_put(new->uid_keyring);
|
||||
key_put(new->session_keyring);
|
||||
kmem_cache_free(uid_cachep, new);
|
||||
|
|
@ -209,6 +386,9 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
|
|||
spin_unlock_irq(&uidhash_lock);
|
||||
|
||||
}
|
||||
|
||||
uids_mutex_unlock();
|
||||
|
||||
return up;
|
||||
}
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue