android_kernel_xiaomi_sm8350/kernel/sched_rt.c
Srivatsa Vaddagiri d842de871c sched: cpu accounting controller (V2)
Commit cfb5285660 removed a useful feature for
us, which provided a cpu accounting resource controller.  This feature would be
useful if someone wants to group tasks only for accounting purpose and doesnt
really want to exercise any control over their cpu consumption.

The patch below reintroduces the feature. It is based on Paul Menage's
original patch (Commit 62d0df6406), with
these differences:

        - Removed load average information. I felt it needs more thought (esp
	  to deal with SMP and virtualized platforms) and can be added for
	  2.6.25 after more discussions.
        - Convert group cpu usage to be nanosecond accurate (as rest of the cfs
	  stats are) and invoke cpuacct_charge() from the respective scheduler
	  classes
	- Make accounting scalable on SMP systems by splitting the usage
	  counter to be per-cpu
	- Move the code from kernel/cpu_acct.c to kernel/sched.c (since the
	  code is not big enough to warrant a new file and also this rightly
	  needs to live inside the scheduler. Also things like accessing
	  rq->lock while reading cpu usage becomes easier if the code lived in
	  kernel/sched.c)

The patch also modifies the cpu controller not to provide the same accounting
information.

Tested-by: Balbir Singh <balbir@linux.vnet.ibm.com>

 Tested the patches on top of 2.6.24-rc3. The patches work fine. Ran
 some simple tests like cpuspin (spin on the cpu), ran several tasks in
 the same group and timed them. Compared their time stamps with
 cpuacct.usage.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-12-02 20:04:49 +01:00

259 lines
5.8 KiB
C

/*
* Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
* policies)
*/
/*
* Update the current task's runtime statistics. Skip current tasks that
* are not in our scheduling class.
*/
static void update_curr_rt(struct rq *rq)
{
struct task_struct *curr = rq->curr;
u64 delta_exec;
if (!task_has_rt_policy(curr))
return;
delta_exec = rq->clock - curr->se.exec_start;
if (unlikely((s64)delta_exec < 0))
delta_exec = 0;
schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec));
curr->se.sum_exec_runtime += delta_exec;
curr->se.exec_start = rq->clock;
cpuacct_charge(curr, delta_exec);
}
static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
{
struct rt_prio_array *array = &rq->rt.active;
list_add_tail(&p->run_list, array->queue + p->prio);
__set_bit(p->prio, array->bitmap);
}
/*
* Adding/removing a task to/from a priority array:
*/
static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
{
struct rt_prio_array *array = &rq->rt.active;
update_curr_rt(rq);
list_del(&p->run_list);
if (list_empty(array->queue + p->prio))
__clear_bit(p->prio, array->bitmap);
}
/*
* Put task to the end of the run list without the overhead of dequeue
* followed by enqueue.
*/
static void requeue_task_rt(struct rq *rq, struct task_struct *p)
{
struct rt_prio_array *array = &rq->rt.active;
list_move_tail(&p->run_list, array->queue + p->prio);
}
static void
yield_task_rt(struct rq *rq)
{
requeue_task_rt(rq, rq->curr);
}
/*
* Preempt the current task with a newly woken task if needed:
*/
static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
{
if (p->prio < rq->curr->prio)
resched_task(rq->curr);
}
static struct task_struct *pick_next_task_rt(struct rq *rq)
{
struct rt_prio_array *array = &rq->rt.active;
struct task_struct *next;
struct list_head *queue;
int idx;
idx = sched_find_first_bit(array->bitmap);
if (idx >= MAX_RT_PRIO)
return NULL;
queue = array->queue + idx;
next = list_entry(queue->next, struct task_struct, run_list);
next->se.exec_start = rq->clock;
return next;
}
static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
{
update_curr_rt(rq);
p->se.exec_start = 0;
}
#ifdef CONFIG_SMP
/*
* Load-balancing iterator. Note: while the runqueue stays locked
* during the whole iteration, the current task might be
* dequeued so the iterator has to be dequeue-safe. Here we
* achieve that by always pre-iterating before returning
* the current task:
*/
static struct task_struct *load_balance_start_rt(void *arg)
{
struct rq *rq = arg;
struct rt_prio_array *array = &rq->rt.active;
struct list_head *head, *curr;
struct task_struct *p;
int idx;
idx = sched_find_first_bit(array->bitmap);
if (idx >= MAX_RT_PRIO)
return NULL;
head = array->queue + idx;
curr = head->prev;
p = list_entry(curr, struct task_struct, run_list);
curr = curr->prev;
rq->rt.rt_load_balance_idx = idx;
rq->rt.rt_load_balance_head = head;
rq->rt.rt_load_balance_curr = curr;
return p;
}
static struct task_struct *load_balance_next_rt(void *arg)
{
struct rq *rq = arg;
struct rt_prio_array *array = &rq->rt.active;
struct list_head *head, *curr;
struct task_struct *p;
int idx;
idx = rq->rt.rt_load_balance_idx;
head = rq->rt.rt_load_balance_head;
curr = rq->rt.rt_load_balance_curr;
/*
* If we arrived back to the head again then
* iterate to the next queue (if any):
*/
if (unlikely(head == curr)) {
int next_idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
if (next_idx >= MAX_RT_PRIO)
return NULL;
idx = next_idx;
head = array->queue + idx;
curr = head->prev;
rq->rt.rt_load_balance_idx = idx;
rq->rt.rt_load_balance_head = head;
}
p = list_entry(curr, struct task_struct, run_list);
curr = curr->prev;
rq->rt.rt_load_balance_curr = curr;
return p;
}
static unsigned long
load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned, int *this_best_prio)
{
struct rq_iterator rt_rq_iterator;
rt_rq_iterator.start = load_balance_start_rt;
rt_rq_iterator.next = load_balance_next_rt;
/* pass 'busiest' rq argument into
* load_balance_[start|next]_rt iterators
*/
rt_rq_iterator.arg = busiest;
return balance_tasks(this_rq, this_cpu, busiest, max_load_move, sd,
idle, all_pinned, this_best_prio, &rt_rq_iterator);
}
static int
move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle)
{
struct rq_iterator rt_rq_iterator;
rt_rq_iterator.start = load_balance_start_rt;
rt_rq_iterator.next = load_balance_next_rt;
rt_rq_iterator.arg = busiest;
return iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
&rt_rq_iterator);
}
#endif
static void task_tick_rt(struct rq *rq, struct task_struct *p)
{
/*
* RR tasks need a special form of timeslice management.
* FIFO tasks have no timeslices.
*/
if (p->policy != SCHED_RR)
return;
if (--p->time_slice)
return;
p->time_slice = DEF_TIMESLICE;
/*
* Requeue to the end of queue if we are not the only element
* on the queue:
*/
if (p->run_list.prev != p->run_list.next) {
requeue_task_rt(rq, p);
set_tsk_need_resched(p);
}
}
static void set_curr_task_rt(struct rq *rq)
{
struct task_struct *p = rq->curr;
p->se.exec_start = rq->clock;
}
const struct sched_class rt_sched_class = {
.next = &fair_sched_class,
.enqueue_task = enqueue_task_rt,
.dequeue_task = dequeue_task_rt,
.yield_task = yield_task_rt,
.check_preempt_curr = check_preempt_curr_rt,
.pick_next_task = pick_next_task_rt,
.put_prev_task = put_prev_task_rt,
#ifdef CONFIG_SMP
.load_balance = load_balance_rt,
.move_one_task = move_one_task_rt,
#endif
.set_curr_task = set_curr_task_rt,
.task_tick = task_tick_rt,
};