/*
* Return the group to which this tasks belongs.
*
- * We use task_subsys_state_check() and extend the RCU verification with
- * pi->lock and rq->lock because cpu_cgroup_attach() holds those locks for each
- * task it moves into the cgroup. Therefore by holding either of those locks,
- * we pin the task to the current cgroup.
+ * We cannot use task_subsys_state() and friends because the cgroup
+ * subsystem changes that value before the cgroup_subsys::attach() method
+ * is called, therefore we cannot pin it and might observe the wrong value.
+ *
+ * The same is true for autogroup's p->signal->autogroup->tg, the autogroup
+ * core changes this before calling sched_move_task().
+ *
+ * Instead we use a 'copy' which is updated from sched_move_task() while
+ * holding both task_struct::pi_lock and rq::lock.
*/
static inline struct task_group *task_group(struct task_struct *p)
{
- struct task_group *tg;
- struct cgroup_subsys_state *css;
-
- css = task_subsys_state_check(p, cpu_cgroup_subsys_id,
- lockdep_is_held(&p->pi_lock) ||
- lockdep_is_held(&task_rq(p)->lock));
- tg = container_of(css, struct task_group, css);
-
- return autogroup_task_group(p, tg);
+ return p->sched_task_group;
}
/* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
static void update_sysctl(void);
static int get_update_sysctl_factor(void);
-static void update_cpu_load(struct rq *this_rq);
+static void update_idle_cpu_load(struct rq *this_rq);
static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
{
* a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
*
* sched_move_task() holds both and thus holding either pins the cgroup,
- * see set_task_rq().
+ * see task_group().
*
* Furthermore, all task_rq users should acquire both locks, see
* task_rq_lock().
{
struct rq *rq = task_rq(p);
- BUG_ON(rq != this_rq());
- BUG_ON(p == current);
+ if (WARN_ON_ONCE(rq != this_rq()) ||
+ WARN_ON_ONCE(p == current))
+ return;
+
lockdep_assert_held(&rq->lock);
if (!raw_spin_trylock(&p->pi_lock)) {
*/
int wake_up_process(struct task_struct *p)
{
- return try_to_wake_up(p, TASK_ALL, 0);
+ WARN_ON(task_is_stopped_or_traced(p));
+ return try_to_wake_up(p, TASK_NORMAL, 0);
}
EXPORT_SYMBOL(wake_up_process);
* scheduler tick (TICK_NSEC). With tickless idle this will not be called
* every tick. We fix it up based on jiffies.
*/
-static void update_cpu_load(struct rq *this_rq)
+static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
+ unsigned long pending_updates)
{
- unsigned long this_load = this_rq->load.weight;
- unsigned long curr_jiffies = jiffies;
- unsigned long pending_updates;
int i, scale;
this_rq->nr_load_updates++;
- /* Avoid repeated calls on same jiffy, when moving in and out of idle */
- if (curr_jiffies == this_rq->last_load_update_tick)
- return;
-
- pending_updates = curr_jiffies - this_rq->last_load_update_tick;
- this_rq->last_load_update_tick = curr_jiffies;
-
/* Update our load: */
this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */
for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
sched_avg_update(this_rq);
}
+#ifdef CONFIG_NO_HZ
+/*
+ * There is no sane way to deal with nohz on smp when using jiffies because the
+ * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
+ * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}.
+ *
+ * Therefore we cannot use the delta approach from the regular tick since that
+ * would seriously skew the load calculation. However we'll make do for those
+ * updates happening while idle (nohz_idle_balance) or coming out of idle
+ * (tick_nohz_idle_exit).
+ *
+ * This means we might still be one tick off for nohz periods.
+ */
+
+/*
+ * Called from nohz_idle_balance() to update the load ratings before doing the
+ * idle balance.
+ */
+static void update_idle_cpu_load(struct rq *this_rq)
+{
+ unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
+ unsigned long load = this_rq->load.weight;
+ unsigned long pending_updates;
+
+ /*
+ * bail if there's load or we're actually up-to-date.
+ */
+ if (load || curr_jiffies == this_rq->last_load_update_tick)
+ return;
+
+ pending_updates = curr_jiffies - this_rq->last_load_update_tick;
+ this_rq->last_load_update_tick = curr_jiffies;
+
+ __update_cpu_load(this_rq, load, pending_updates);
+}
+
+/*
+ * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
+ */
+void update_cpu_load_nohz(void)
+{
+ struct rq *this_rq = this_rq();
+ unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
+ unsigned long pending_updates;
+
+ if (curr_jiffies == this_rq->last_load_update_tick)
+ return;
+
+ raw_spin_lock(&this_rq->lock);
+ pending_updates = curr_jiffies - this_rq->last_load_update_tick;
+ if (pending_updates) {
+ this_rq->last_load_update_tick = curr_jiffies;
+ /*
+ * We were idle, this means load 0, the current load might be
+ * !0 due to remote wakeups and the sort.
+ */
+ __update_cpu_load(this_rq, 0, pending_updates);
+ }
+ raw_spin_unlock(&this_rq->lock);
+}
+#endif /* CONFIG_NO_HZ */
+
+/*
+ * Called from scheduler_tick()
+ */
static void update_cpu_load_active(struct rq *this_rq)
{
- update_cpu_load(this_rq);
+ /*
+ * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
+ */
+ this_rq->last_load_update_tick = jiffies;
+ __update_cpu_load(this_rq, this_rq->load.weight, 1);
calc_load_account_active(this_rq);
}
# define nsecs_to_cputime(__nsecs) nsecs_to_jiffies(__nsecs)
#endif
+static cputime_t scale_utime(cputime_t utime, cputime_t rtime, cputime_t total)
+{
+ u64 temp = (__force u64) rtime;
+
+ temp *= (__force u64) utime;
+
+ if (sizeof(cputime_t) == 4)
+ temp = div_u64(temp, (__force u32) total);
+ else
+ temp = div64_u64(temp, (__force u64) total);
+
+ return (__force cputime_t) temp;
+}
+
void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
cputime_t rtime, utime = p->utime, total = cputime_add(utime, p->stime);
*/
rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
- if (total) {
- u64 temp = rtime;
-
- temp *= utime;
- do_div(temp, total);
- utime = (cputime_t)temp;
- } else
+ if (total)
+ utime = scale_utime(utime, rtime, total);
+ else
utime = rtime;
/*
total = cputime_add(cputime.utime, cputime.stime);
rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
- if (total) {
- u64 temp = rtime;
-
- temp *= cputime.utime;
- do_div(temp, total);
- utime = (cputime_t)temp;
- } else
+ if (total)
+ utime = scale_utime(cputime.utime, rtime, total);
+ else
utime = rtime;
sig->prev_utime = max(sig->prev_utime, utime);
return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
capable(CAP_SYS_NICE));
}
+EXPORT_SYMBOL_GPL(can_nice);
#ifdef __ARCH_WANT_SYS_NICE
}
#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
+static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
+
/*
* Update cpusets according to cpu_active mask. If cpusets are
* disabled, cpuset_update_active_cpus() becomes a simple wrapper
* around partition_sched_domains().
+ *
+ * If we come here as part of a suspend/resume, don't touch cpusets because we
+ * want to restore it back to its original state upon resume anyway.
*/
static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
- switch (action & ~CPU_TASKS_FROZEN) {
+ switch (action) {
+ case CPU_ONLINE_FROZEN:
+ case CPU_DOWN_FAILED_FROZEN:
+
+ /*
+ * num_cpus_frozen tracks how many CPUs are involved in suspend
+ * resume sequence. As long as this is not the last online
+ * operation in the resume sequence, just build a single sched
+ * domain, ignoring cpusets.
+ */
+ num_cpus_frozen--;
+ if (likely(num_cpus_frozen)) {
+ partition_sched_domains(1, NULL, NULL);
+ break;
+ }
+
+ /*
+ * This is the last CPU online operation. So fall through and
+ * restore the original sched domains by considering the
+ * cpuset configurations.
+ */
+
case CPU_ONLINE:
case CPU_DOWN_FAILED:
cpuset_update_active_cpus();
- return NOTIFY_OK;
+ break;
default:
return NOTIFY_DONE;
}
+ return NOTIFY_OK;
}
static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
- switch (action & ~CPU_TASKS_FROZEN) {
+ switch (action) {
case CPU_DOWN_PREPARE:
cpuset_update_active_cpus();
- return NOTIFY_OK;
+ break;
+ case CPU_DOWN_PREPARE_FROZEN:
+ num_cpus_frozen++;
+ partition_sched_domains(1, NULL, NULL);
+ break;
default:
return NOTIFY_DONE;
}
+ return NOTIFY_OK;
}
static int update_runtime(struct notifier_block *nfb,
*/
void sched_move_task(struct task_struct *tsk)
{
+ struct task_group *tg;
int on_rq, running;
unsigned long flags;
struct rq *rq;
if (unlikely(running))
tsk->sched_class->put_prev_task(rq, tsk);
+ tg = container_of(task_subsys_state_check(tsk, cpu_cgroup_subsys_id,
+ lockdep_is_held(&tsk->sighand->siglock)),
+ struct task_group, css);
+ tg = autogroup_task_group(tsk, tg);
+ tsk->sched_task_group = tg;
+
#ifdef CONFIG_FAIR_GROUP_SCHED
if (tsk->sched_class->task_move_group)
tsk->sched_class->task_move_group(tsk, on_rq);
git.openpandora.org / pandora-kernel.git / blobdiff