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

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: do not count frozen tasks toward load
  sched: refresh MAINTAINERS entry
  sched: Print sched_group::__cpu_power in sched_domain_debug
  cpuacct: add per-cgroup utime/stime statistics
  posixtimers, sched: Fix posix clock monotonicity
  sched_rt: don't allocate cpumask in fastpath
  cpuacct: make cpuacct hierarchy walk in cpuacct_charge() safe when rcupreempt is used -v2

7 files changed, 178 insertions, 34 deletions

diff --git a/Documentation/cgroups/cpuacct.txt b/Documentation/cgroups/cpuacct.txt
index bb775fbe43d7..8b930946c52a 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+- It is possible to see slightly outdated values for user and system times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 1f02d96a5dbf..5d843588e1de 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 98e1fe51601d..b4c38bc8049c 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 bb53185d8c78..c9dcf98b4463 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 6cc1fd5d5072..5724508c3b66 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 1e00bfacf9b8..cdd3c89574cd 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 299d012b4394..f2c66f8f9712 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 */