[GIT PULL] scheduler fixes

Ingo Molnar
2012-08-20T09:12:31Z

Linus,

Please pull the latest sched-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-for-linus

HEAD: 8f6189684eb4e85e6c593cd710693f09c944450a sched: Fix migration thread runtime bogosity

Thanks,

Ingo

------------------>
Mike Galbraith (3):
sched,cgroup: Fix up task_groups list
sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttled
sched: Fix migration thread runtime bogosity

Peter Zijlstra (1):
sched, cgroup: Reduce rq->lock hold times for large cgroup hierarchies

Stanislaw Gruszka (1):
sched: fix divide by zero at {thread_group,task}_times

kernel/sched/core.c | 35 +++++++++++++++++++++--------------
kernel/sched/fair.c | 11 +++++++++--
kernel/sched/rt.c | 13 +++++++++++++
kernel/sched/sched.h | 8 ++++++--
kernel/sched/stop_task.c | 22 +++++++++++++++++++++-
5 files changed, 70 insertions(+), 19 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2cb4e77..6aa212f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3142,6 +3142,20 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
# 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 = utime + p->stime;
@@ -3151,13 +3165,9 @@ void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
*/
rtime = nsecs_to_cputime(p->se.sum_exec_runtime);

- if (total) {
- u64 temp = (__force u64) rtime;
-
- temp *= (__force u64) utime;
- do_div(temp, (__force u32) total);
- utime = (__force cputime_t) temp;
- } else
+ if (total)
+ utime = scale_utime(utime, rtime, total);
+ else
utime = rtime;

/*
@@ -3184,13 +3194,9 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
total = cputime.utime + cputime.stime;
rtime = nsecs_to_cputime(cputime.sum_exec_runtime);

- if (total) {
- u64 temp = (__force u64) rtime;
-
- temp *= (__force u64) cputime.utime;
- do_div(temp, (__force u32) total);
- utime = (__force cputime_t) temp;
- } else
+ if (total)
+ utime = scale_utime(cputime.utime, rtime, total);
+ else
utime = rtime;

sig->prev_utime = max(sig->prev_utime, utime);
@@ -7246,6 +7252,7 @@ int in_sched_functions(unsigned long addr)

#ifdef CONFIG_CGROUP_SCHED
struct task_group root_task_group;
+LIST_HEAD(task_groups);
#endif

DECLARE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d0cc03b..c219bf8 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3387,6 +3387,14 @@ static int tg_load_down(struct task_group *tg, void *data)

static void update_h_load(long cpu)
{
+ struct rq *rq = cpu_rq(cpu);
+ unsigned long now = jiffies;
+
+ if (rq->h_load_throttle == now)
+ return;
+
+ rq->h_load_throttle = now;
+
rcu_read_lock();
walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
rcu_read_unlock();
@@ -4293,11 +4301,10 @@ redo:
env.src_rq = busiest;
env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running);

+ update_h_load(env.src_cpu);
more_balance:
local_irq_save(flags);
double_rq_lock(this_rq, busiest);
- if (!env.loop)
- update_h_load(env.src_cpu);

/*
* cur_ld_moved - load moved in current iteration
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 573e1ca..944cb68 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -788,6 +788,19 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
const struct cpumask *span;

span = sched_rt_period_mask();
+#ifdef CONFIG_RT_GROUP_SCHED
+ /*
+ * FIXME: isolated CPUs should really leave the root task group,
+ * whether they are isolcpus or were isolated via cpusets, lest
+ * the timer run on a CPU which does not service all runqueues,
+ * potentially leaving other CPUs indefinitely throttled. If
+ * isolation is really required, the user will turn the throttle
+ * off to kill the perturbations it causes anyway. Meanwhile,
+ * this maintains functionality for boot and/or troubleshooting.
+ */
+ if (rt_b == &root_task_group.rt_bandwidth)
+ span = cpu_online_mask;
+#endif
for_each_cpu(i, span) {
int enqueue = 0;
struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c35a1a7..f6714d0 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -80,7 +80,7 @@ extern struct mutex sched_domains_mutex;
struct cfs_rq;
struct rt_rq;

-static LIST_HEAD(task_groups);
+extern struct list_head task_groups;

struct cfs_bandwidth {
#ifdef CONFIG_CFS_BANDWIDTH
@@ -374,7 +374,11 @@ struct rq {
#ifdef CONFIG_FAIR_GROUP_SCHED
/* list of leaf cfs_rq on this cpu: */
struct list_head leaf_cfs_rq_list;
-#endif
+#ifdef CONFIG_SMP
+ unsigned long h_load_throttle;
+#endif /* CONFIG_SMP */
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
#ifdef CONFIG_RT_GROUP_SCHED
struct list_head leaf_rt_rq_list;
#endif
diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
index 7b386e8..da5eb5b 100644
--- a/kernel/sched/stop_task.c
+++ b/kernel/sched/stop_task.c
@@ -27,8 +27,10 @@ static struct task_struct *pick_next_task_stop(struct rq *rq)
{
struct task_struct *stop = rq->stop;

- if (stop && stop->on_rq)
+ if (stop && stop->on_rq) {
+ stop->se.exec_start = rq->clock_task;
return stop;
+ }

return NULL;
}
@@ -52,6 +54,21 @@ static void yield_task_stop(struct rq *rq)

static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
{
+ struct task_struct *curr = rq->curr;
+ u64 delta_exec;
+
+ delta_exec = rq->clock_task - curr->se.exec_start;
+ if (unlikely((s64)delta_exec < 0))
+ delta_exec = 0;
+
+ schedstat_set(curr->se.statistics.exec_max,
+ max(curr->se.statistics.exec_max, delta_exec));
+
+ curr->se.sum_exec_runtime += delta_exec;
+ account_group_exec_runtime(curr, delta_exec);
+
+ curr->se.exec_start = rq->clock_task;
+ cpuacct_charge(curr, delta_exec);
}

static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued)
@@ -60,6 +77,9 @@ static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued)

static void set_curr_task_stop(struct rq *rq)
{
+ struct task_struct *stop = rq->stop;
+
+ stop->se.exec_start = rq->clock_task;
}

static void switched_to_stop(struct rq *rq, struct task_struct *p)