[GIT PULL] scheduler fixes

Ingo Molnar
2009-04-09T15:42:26Z

Linus,

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

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git sched-fixes-for-linus

Thanks,

Ingo

------------------>
Bharata B Rao (2):
cpuacct: make cpuacct hierarchy walk in cpuacct_charge() safe when rcupreempt is used -v2
cpuacct: add per-cgroup utime/stime statistics

Gautham R Shenoy (1):
sched: Print sched_group::__cpu_power in sched_domain_debug

Hidetoshi Seto (1):
posixtimers, sched: Fix posix clock monotonicity

Ingo Molnar (1):
sched: refresh MAINTAINERS entry

Nathan Lynch (1):
sched: do not count frozen tasks toward load

Rusty Russell (1):
sched_rt: don't allocate cpumask in fastpath

Documentation/cgroups/cpuacct.txt | 18 ++++
MAINTAINERS | 4 +-
include/linux/sched.h | 3 +-
kernel/posix-cpu-timers.c | 7 +-
kernel/sched.c | 160 +++++++++++++++++++++++++++++++++----
kernel/sched_cpupri.c | 5 +-
kernel/sched_rt.c | 15 +---
7 files changed, 178 insertions(+), 34 deletions(-)

diff --git a/Documentation/cgroups/cpuacct.txt b/Documentation/cgroups/cpuacct.txt
index bb775fb..8b93094 100644
--- a/Documentation/cgroups/cpuacct.txt
+++ b/Documentation/cgroups/cpuacct.txt
@@ -30,3 +30,21 @@ The above steps create a new group g1 and move the current shell
process (bash) into it. CPU time consumed by this bash and its children
can be obtained from g1/cpuacct.usage and the same is accumulated in
/cgroups/cpuacct.usage also.
+
+cpuacct.stat file lists a few statistics which further divide the
+CPU time obtained by the cgroup into user and system times. Currently
+the following statistics are supported:
+
+user: Time spent by tasks of the cgroup in user mode.
+system: Time spent by tasks of the cgroup in kernel mode.
+
+user and system are in USER_HZ unit.
+
+cpuacct controller uses percpu_counter interface to collect user and
+system times. This has two side effects:
+
+- It is theoretically possible to see wrong values for user and system times.
+ This is because percpu_counter_read() on 32bit systems isn't safe
+ against concurrent writes.
+- It is possible to see slightly outdated values for user and system times
+ due to the batch processing nature of percpu_counter.
diff --git a/MAINTAINERS b/MAINTAINERS
index c3b2159..718b50a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3873,8 +3873,8 @@ S: Maintained
SCHEDULER
P: Ingo Molnar
M: mingo@elte.hu
-P: Robert Love [the preemptible kernel bits]
-M: rml@tech9.net
+P: Peter Zijlstra
+M: peterz@infradead.org
L: linux-kernel@vger.kernel.org
S: Maintained

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 98e1fe5..b4c38bc 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -205,7 +205,8 @@ extern unsigned long long time_sync_thresh;
#define task_is_stopped_or_traced(task) \
((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0)
#define task_contributes_to_load(task) \
- ((task->state & TASK_UNINTERRUPTIBLE) != 0)
+ ((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
+ (task->flags & PF_FROZEN) == 0)

#define __set_task_state(tsk, state_value) \
do { (tsk)->state = (state_value); } while (0)
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 8e5d9a6..6f7b869 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -224,7 +224,7 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
cpu->cpu = virt_ticks(p);
break;
case CPUCLOCK_SCHED:
- cpu->sched = p->se.sum_exec_runtime + task_delta_exec(p);
+ cpu->sched = task_sched_runtime(p);
break;
}
return 0;
@@ -305,18 +305,19 @@ static int cpu_clock_sample_group(const clockid_t which_clock,
{
struct task_cputime cputime;

- thread_group_cputime(p, &cputime);
switch (CPUCLOCK_WHICH(which_clock)) {
default:
return -EINVAL;
case CPUCLOCK_PROF:
+ thread_group_cputime(p, &cputime);
cpu->cpu = cputime_add(cputime.utime, cputime.stime);
break;
case CPUCLOCK_VIRT:
+ thread_group_cputime(p, &cputime);
cpu->cpu = cputime.utime;
break;
case CPUCLOCK_SCHED:
- cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
+ cpu->sched = thread_group_sched_runtime(p);
break;
}
return 0;
diff --git a/kernel/sched.c b/kernel/sched.c
index 6cc1fd5..5724508 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1418,10 +1418,22 @@ iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct rq_iterator *iterator);
#endif

+/* Time spent by the tasks of the cpu accounting group executing in ... */
+enum cpuacct_stat_index {
+ CPUACCT_STAT_USER, /* ... user mode */
+ CPUACCT_STAT_SYSTEM, /* ... kernel mode */
+
+ CPUACCT_STAT_NSTATS,
+};
+
#ifdef CONFIG_CGROUP_CPUACCT
static void cpuacct_charge(struct task_struct *tsk, u64 cputime);
+static void cpuacct_update_stats(struct task_struct *tsk,
+ enum cpuacct_stat_index idx, cputime_t val);
#else
static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {}
+static inline void cpuacct_update_stats(struct task_struct *tsk,
+ enum cpuacct_stat_index idx, cputime_t val) {}
#endif

static inline void inc_cpu_load(struct rq *rq, unsigned long load)
@@ -4511,9 +4523,25 @@ DEFINE_PER_CPU(struct kernel_stat, kstat);
EXPORT_PER_CPU_SYMBOL(kstat);

/*
- * Return any ns on the sched_clock that have not yet been banked in
+ * Return any ns on the sched_clock that have not yet been accounted in
* @p in case that task is currently running.
+ *
+ * Called with task_rq_lock() held on @rq.
*/
+static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
+{
+ u64 ns = 0;
+
+ if (task_current(rq, p)) {
+ update_rq_clock(rq);
+ ns = rq->clock - p->se.exec_start;
+ if ((s64)ns < 0)
+ ns = 0;
+ }
+
+ return ns;
+}
+
unsigned long long task_delta_exec(struct task_struct *p)
{
unsigned long flags;
@@ -4521,16 +4549,49 @@ unsigned long long task_delta_exec(struct task_struct *p)
u64 ns = 0;

rq = task_rq_lock(p, &flags);
+ ns = do_task_delta_exec(p, rq);
+ task_rq_unlock(rq, &flags);

- if (task_current(rq, p)) {
- u64 delta_exec;
+ return ns;
+}

- update_rq_clock(rq);
- delta_exec = rq->clock - p->se.exec_start;
- if ((s64)delta_exec > 0)
- ns = delta_exec;
- }
+/*
+ * Return accounted runtime for the task.
+ * In case the task is currently running, return the runtime plus current's
+ * pending runtime that have not been accounted yet.
+ */
+unsigned long long task_sched_runtime(struct task_struct *p)
+{
+ unsigned long flags;
+ struct rq *rq;
+ u64 ns = 0;
+
+ rq = task_rq_lock(p, &flags);
+ ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
+ task_rq_unlock(rq, &flags);
+
+ return ns;
+}
+
+/*
+ * Return sum_exec_runtime for the thread group.
+ * In case the task is currently running, return the sum plus current's
+ * pending runtime that have not been accounted yet.
+ *
+ * Note that the thread group might have other running tasks as well,
+ * so the return value not includes other pending runtime that other
+ * running tasks might have.
+ */
+unsigned long long thread_group_sched_runtime(struct task_struct *p)
+{
+ struct task_cputime totals;
+ unsigned long flags;
+ struct rq *rq;
+ u64 ns;

+ rq = task_rq_lock(p, &flags);
+ thread_group_cputime(p, &totals);
+ ns = totals.sum_exec_runtime + do_task_delta_exec(p, rq);
task_rq_unlock(rq, &flags);

return ns;
@@ -4559,6 +4620,8 @@ void account_user_time(struct task_struct *p, cputime_t cputime,
cpustat->nice = cputime64_add(cpustat->nice, tmp);
else
cpustat->user = cputime64_add(cpustat->user, tmp);
+
+ cpuacct_update_stats(p, CPUACCT_STAT_USER, cputime);
/* Account for user time used */
acct_update_integrals(p);
}
@@ -4620,6 +4683,8 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
else
cpustat->system = cputime64_add(cpustat->system, tmp);

+ cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime);
+
/* Account for system time used */
acct_update_integrals(p);
}
@@ -7302,7 +7367,8 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
cpumask_or(groupmask, groupmask, sched_group_cpus(group));

cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
- printk(KERN_CONT " %s", str);
+ printk(KERN_CONT " %s (__cpu_power = %d)", str,
+ group->__cpu_power);

group = group->next;
} while (group != sd->groups);
@@ -9925,6 +9991,7 @@ struct cpuacct {
struct cgroup_subsys_state css;
/* cpuusage holds pointer to a u64-type object on every cpu */
u64 *cpuusage;
+ struct percpu_counter cpustat[CPUACCT_STAT_NSTATS];
struct cpuacct *parent;
};

@@ -9949,20 +10016,32 @@ static struct cgroup_subsys_state *cpuacct_create(
struct cgroup_subsys *ss, struct cgroup *cgrp)
{
struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
+ int i;

if (!ca)
- return ERR_PTR(-ENOMEM);
+ goto out;

ca->cpuusage = alloc_percpu(u64);
- if (!ca->cpuusage) {
- kfree(ca);
- return ERR_PTR(-ENOMEM);
- }
+ if (!ca->cpuusage)
+ goto out_free_ca;
+
+ for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
+ if (percpu_counter_init(&ca->cpustat[i], 0))
+ goto out_free_counters;

if (cgrp->parent)
ca->parent = cgroup_ca(cgrp->parent);

return &ca->css;
+
+out_free_counters:
+ while (--i >= 0)
+ percpu_counter_destroy(&ca->cpustat[i]);
+ free_percpu(ca->cpuusage);
+out_free_ca:
+ kfree(ca);
+out:
+ return ERR_PTR(-ENOMEM);
}

/* destroy an existing cpu accounting group */
@@ -9970,7 +10049,10 @@ static void
cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
{
struct cpuacct *ca = cgroup_ca(cgrp);
+ int i;

+ for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
+ percpu_counter_destroy(&ca->cpustat[i]);
free_percpu(ca->cpuusage);
kfree(ca);
}
@@ -10057,6 +10139,25 @@ static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft,
return 0;
}

+static const char *cpuacct_stat_desc[] = {
+ [CPUACCT_STAT_USER] = "user",
+ [CPUACCT_STAT_SYSTEM] = "system",
+};
+
+static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
+ struct cgroup_map_cb *cb)
+{
+ struct cpuacct *ca = cgroup_ca(cgrp);
+ int i;
+
+ for (i = 0; i < CPUACCT_STAT_NSTATS; i++) {
+ s64 val = percpu_counter_read(&ca->cpustat[i]);
+ val = cputime64_to_clock_t(val);
+ cb->fill(cb, cpuacct_stat_desc[i], val);
+ }
+ return 0;
+}
+
static struct cftype files[] = {
{
.name = "usage",
@@ -10067,7 +10168,10 @@ static struct cftype files[] = {
.name = "usage_percpu",
.read_seq_string = cpuacct_percpu_seq_read,
},
-
+ {
+ .name = "stat",
+ .read_map = cpuacct_stats_show,
+ },
};

static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
@@ -10089,12 +10193,38 @@ static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
return;

cpu = task_cpu(tsk);
+
+ rcu_read_lock();
+
ca = task_ca(tsk);

for (; ca; ca = ca->parent) {
u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
*cpuusage += cputime;
}
+
+ rcu_read_unlock();
+}
+
+/*
+ * Charge the system/user time to the task's accounting group.
+ */
+static void cpuacct_update_stats(struct task_struct *tsk,
+ enum cpuacct_stat_index idx, cputime_t val)
+{
+ struct cpuacct *ca;
+
+ if (unlikely(!cpuacct_subsys.active))
+ return;
+
+ rcu_read_lock();
+ ca = task_ca(tsk);
+
+ do {
+ percpu_counter_add(&ca->cpustat[idx], val);
+ ca = ca->parent;
+ } while (ca);
+ rcu_read_unlock();
}

struct cgroup_subsys cpuacct_subsys = {
diff --git a/kernel/sched_cpupri.c b/kernel/sched_cpupri.c
index 1e00bfa..cdd3c89 100644
--- a/kernel/sched_cpupri.c
+++ b/kernel/sched_cpupri.c
@@ -55,7 +55,7 @@ static int convert_prio(int prio)
* cpupri_find - find the best (lowest-pri) CPU in the system
* @cp: The cpupri context
* @p: The task
- * @lowest_mask: A mask to fill in with selected CPUs
+ * @lowest_mask: A mask to fill in with selected CPUs (or NULL)
*
* Note: This function returns the recommended CPUs as calculated during the
* current invokation. By the time the call returns, the CPUs may have in
@@ -81,7 +81,8 @@ int cpupri_find(struct cpupri *cp, struct task_struct *p,
if (cpumask_any_and(&p->cpus_allowed, vec->mask) >= nr_cpu_ids)
continue;

- cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask);
+ if (lowest_mask)
+ cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask);
return 1;
}

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 299d012..f2c66f8 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -948,20 +948,15 @@ static int select_task_rq_rt(struct task_struct *p, int sync)

static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
{
- cpumask_var_t mask;
-
if (rq->curr->rt.nr_cpus_allowed == 1)
return;

- if (!alloc_cpumask_var(&mask, GFP_ATOMIC))
- return;
-
if (p->rt.nr_cpus_allowed != 1
- && cpupri_find(&rq->rd->cpupri, p, mask))
- goto free;
+ && cpupri_find(&rq->rd->cpupri, p, NULL))
+ return;

- if (!cpupri_find(&rq->rd->cpupri, rq->curr, mask))
- goto free;
+ if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
+ return;

/*
* There appears to be other cpus that can accept
@@ -970,8 +965,6 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
*/
requeue_task_rt(rq, p, 1);
resched_task(rq->curr);
-free:
- free_cpumask_var(mask);
}

#endif /* CONFIG_SMP */