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Subject[PATCH 5/5] Add fair "control groups" scheduler

Enable "cgroup" (formerly containers) based fair group scheduling.
This will let administrator create arbitrary groups of tasks (using
"cgroup" psuedo filesystem) and control their cpu bandwidth usage.

Signed-off-by : Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by : Dhaval Giani <dhaval@linux.vnet.ibm.com>


---
include/linux/cgroup_subsys.h | 6 ++
init/Kconfig | 24 +++++---
kernel/sched.c | 122 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 145 insertions(+), 7 deletions(-)
Index: current/include/linux/cgroup_subsys.h
===================================================================
--- current.orig/include/linux/cgroup_subsys.h
+++ current/include/linux/cgroup_subsys.h
@@ -36,3 +36,9 @@ SUBSYS(mem_cgroup)
#endif

/* */
+
+#ifdef CONFIG_FAIR_CGROUP_SCHED
+SUBSYS(cpu_cgroup)
+#endif
+
+/* */
Index: current/init/Kconfig
===================================================================
--- current.orig/init/Kconfig
+++ current/init/Kconfig
@@ -327,13 +327,6 @@ config FAIR_GROUP_SCHED
This feature lets cpu scheduler recognize task groups and control cpu
bandwidth allocation to such task groups.

-config RESOURCE_COUNTERS
- bool "Resource counters"
- help
- This option enables controller independent resource accounting
- infrastructure that works with cgroups
- depends on CGROUPS
-
choice
depends on FAIR_GROUP_SCHED
prompt "Basis for grouping tasks"
@@ -345,8 +338,25 @@ choice
This option will choose userid as the basis for grouping
tasks, thus providing equal cpu bandwidth to each user.

+ config FAIR_CGROUP_SCHED
+ bool "Control groups"
+ depends on CGROUPS
+ help
+ This option allows you to create arbitrary task groups
+ using the "cgroup" psuedo filesystem and control
+ the cpu bandwidth allocated to each such task group.
+ Refer to Documentation/cgroups.txt for more information
+ on "cgroup" psuedo filesystem.
+
endchoice

+config RESOURCE_COUNTERS
+ bool "Resource counters"
+ help
+ This option enables controller independent resource accounting
+ infrastructure that works with cgroups
+ depends on CGROUPS
+
config SYSFS_DEPRECATED
bool "Create deprecated sysfs files"
default y
Index: current/kernel/sched.c
===================================================================
--- current.orig/kernel/sched.c
+++ current/kernel/sched.c
@@ -179,10 +179,16 @@ EXPORT_SYMBOL_GPL(cpu_clock);

#ifdef CONFIG_FAIR_GROUP_SCHED

+#include <linux/cgroup.h>
+
struct cfs_rq;

/* task group related information */
struct task_grp {
+#ifdef CONFIG_FAIR_CGROUP_SCHED
+ struct cgroup_subsys_state css;
+#endif
+
/* schedulable entities of this group on each cpu */
struct sched_entity **se;
/* runqueue "owned" by this group on each cpu */
@@ -221,6 +227,9 @@ static inline struct task_grp *task_grp(

#ifdef CONFIG_FAIR_USER_SCHED
tg = p->user->tg;
+#elif CONFIG_FAIR_CGROUP_SCHED
+ tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
+ struct task_grp, css);
#else
tg = &init_task_grp;
#endif
@@ -6950,3 +6959,116 @@ int sched_group_set_shares(struct task_g
}

#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+#ifdef CONFIG_FAIR_CGROUP_SCHED
+
+/* return corresponding task_grp object of a cgroup */
+static inline struct task_grp *cgroup_tg(struct cgroup *cont)
+{
+ return container_of(cgroup_subsys_state(cont, cpu_cgroup_subsys_id),
+ struct task_grp, css);
+}
+
+static struct cgroup_subsys_state *
+cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ struct task_grp *tg;
+
+ if (!cont->parent) {
+ /* This is early initialization for the top cgroup */
+ init_task_grp.css.cgroup = cont;
+ return &init_task_grp.css;
+ }
+
+ /* we support only 1-level deep hierarchical scheduler atm */
+ if (cont->parent->parent)
+ return ERR_PTR(-EINVAL);
+
+ tg = sched_create_group();
+ if (IS_ERR(tg))
+ return ERR_PTR(-ENOMEM);
+
+ /* Bind the cgroup to task_grp object we just created */
+ tg->css.cgroup = cont;
+
+ return &tg->css;
+}
+
+static void cpu_cgroup_destroy(struct cgroup_subsys *ss,
+ struct cgroup *cont)
+{
+ struct task_grp *tg = cgroup_tg(cont);
+
+ sched_destroy_group(tg);
+}
+
+static int cpu_cgroup_can_attach(struct cgroup_subsys *ss,
+ struct cgroup *cont, struct task_struct *tsk)
+{
+ /* We don't support RT-tasks being in separate groups */
+ if (tsk->sched_class != &fair_sched_class)
+ return -EINVAL;
+
+ return 0;
+}
+
+static void
+cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cont,
+ struct cgroup *old_cont, struct task_struct *tsk)
+{
+ sched_move_task(tsk);
+}
+
+static ssize_t cpu_shares_write(struct cgroup *cont, struct cftype *cftype,
+ struct file *file, const char __user *userbuf,
+ size_t nbytes, loff_t *ppos)
+{
+ unsigned long shareval;
+ struct task_grp *tg = cgroup_tg(cont);
+ char buffer[2*sizeof(unsigned long) + 1];
+ int rc;
+
+ if (nbytes > 2*sizeof(unsigned long)) /* safety check */
+ return -E2BIG;
+
+ if (copy_from_user(buffer, userbuf, nbytes))
+ return -EFAULT;
+
+ buffer[nbytes] = 0; /* nul-terminate */
+ shareval = simple_strtoul(buffer, NULL, 10);
+
+ rc = sched_group_set_shares(tg, shareval);
+
+ return (rc < 0 ? rc : nbytes);
+}
+
+static u64 cpu_shares_read_uint(struct cgroup *cont, struct cftype *cft)
+{
+ struct task_grp *tg = cgroup_tg(cont);
+
+ return (u64) tg->shares;
+}
+
+static struct cftype cpu_shares = {
+ .name = "shares",
+ .read_uint = cpu_shares_read_uint,
+ .write = cpu_shares_write,
+};
+
+static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ return cgroup_add_file(cont, ss, &cpu_shares);
+}
+
+struct cgroup_subsys cpu_cgroup_subsys = {
+ .name = "cpu",
+ .create = cpu_cgroup_create,
+ .destroy = cpu_cgroup_destroy,
+ .can_attach = cpu_cgroup_can_attach,
+ .attach = cpu_cgroup_attach,
+ .populate = cpu_cgroup_populate,
+ .subsys_id = cpu_cgroup_subsys_id,
+ .early_init = 1,
+};
+
+#endif /* CONFIG_FAIR_CGROUP_SCHED */
--
Regards,
vatsa
-
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