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Subject[PATCH v7 05/11] cpuacct: don't actually do anything.
Date
All the information we have that is needed for cpuusage (and
cpuusage_percpu) is present in schedstats. It is already recorded
in a sane hierarchical way.

If we have CONFIG_SCHEDSTATS, we don't really need to do any extra
work. All former functions become empty inlines.

Signed-off-by: Glauber Costa <glommer@openvz.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Dave Jones <davej@redhat.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Paul Turner <pjt@google.com>
---
kernel/sched/core.c | 102 ++++++++++++++++++++++++++++++++++++++++++---------
kernel/sched/sched.h | 10 +++--
2 files changed, 90 insertions(+), 22 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5ae1adf..0fa0f87 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6787,6 +6787,7 @@ void sched_move_task(struct task_struct *tsk)
task_rq_unlock(rq, tsk, &flags);
}

+#ifndef CONFIG_SCHEDSTATS
void task_group_charge(struct task_struct *tsk, u64 cputime)
{
struct task_group *tg;
@@ -6804,6 +6805,7 @@ void task_group_charge(struct task_struct *tsk, u64 cputime)

rcu_read_unlock();
}
+#endif
#endif /* CONFIG_CGROUP_SCHED */

#if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH)
@@ -7199,22 +7201,92 @@ cpu_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp,
sched_move_task(task);
}

-static u64 task_group_cpuusage_read(struct task_group *tg, int cpu)
+/*
+ * Take rq->lock to make 64-bit write safe on 32-bit platforms.
+ */
+static inline void lock_rq_dword(int cpu)
{
- u64 *cpuusage = per_cpu_ptr(tg->cpuusage, cpu);
- u64 data;
-
#ifndef CONFIG_64BIT
- /*
- * Take rq->lock to make 64-bit read safe on 32-bit platforms.
- */
raw_spin_lock_irq(&cpu_rq(cpu)->lock);
- data = *cpuusage;
+#endif
+}
+
+static inline void unlock_rq_dword(int cpu)
+{
+#ifndef CONFIG_64BIT
raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
+#endif
+}
+
+#ifdef CONFIG_SCHEDSTATS
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static inline u64 cfs_exec_clock(struct task_group *tg, int cpu)
+{
+ return tg->cfs_rq[cpu]->exec_clock - tg->cfs_rq[cpu]->prev_exec_clock;
+}
+
+static inline void cfs_exec_clock_reset(struct task_group *tg, int cpu)
+{
+ tg->cfs_rq[cpu]->prev_exec_clock = tg->cfs_rq[cpu]->exec_clock;
+}
#else
- data = *cpuusage;
+static inline u64 cfs_exec_clock(struct task_group *tg, int cpu)
+{
+}
+
+static inline void cfs_exec_clock_reset(struct task_group *tg, int cpu)
+{
+}
+#endif
+#ifdef CONFIG_RT_GROUP_SCHED
+static inline u64 rt_exec_clock(struct task_group *tg, int cpu)
+{
+ return tg->rt_rq[cpu]->exec_clock - tg->rt_rq[cpu]->prev_exec_clock;
+}
+
+static inline void rt_exec_clock_reset(struct task_group *tg, int cpu)
+{
+ tg->rt_rq[cpu]->prev_exec_clock = tg->rt_rq[cpu]->exec_clock;
+}
+#else
+static inline u64 rt_exec_clock(struct task_group *tg, int cpu)
+{
+ return 0;
+}
+
+static inline void rt_exec_clock_reset(struct task_group *tg, int cpu)
+{
+}
#endif

+static u64 task_group_cpuusage_read(struct task_group *tg, int cpu)
+{
+ u64 ret = 0;
+
+ lock_rq_dword(cpu);
+ ret = cfs_exec_clock(tg, cpu) + rt_exec_clock(tg, cpu);
+ unlock_rq_dword(cpu);
+
+ return ret;
+}
+
+static void task_group_cpuusage_write(struct task_group *tg, int cpu, u64 val)
+{
+ lock_rq_dword(cpu);
+ cfs_exec_clock_reset(tg, cpu);
+ rt_exec_clock_reset(tg, cpu);
+ unlock_rq_dword(cpu);
+}
+#else
+static u64 task_group_cpuusage_read(struct task_group *tg, int cpu)
+{
+ u64 *cpuusage = per_cpu_ptr(tg->cpuusage, cpu);
+ u64 data;
+
+ lock_rq_dword(cpu);
+ data = *cpuusage;
+ unlock_rq_dword(cpu);
+
return data;
}

@@ -7222,17 +7294,11 @@ static void task_group_cpuusage_write(struct task_group *tg, int cpu, u64 val)
{
u64 *cpuusage = per_cpu_ptr(tg->cpuusage, cpu);

-#ifndef CONFIG_64BIT
- /*
- * Take rq->lock to make 64-bit write safe on 32-bit platforms.
- */
- raw_spin_lock_irq(&cpu_rq(cpu)->lock);
+ lock_rq_dword(cpu);
*cpuusage = val;
- raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
-#else
- *cpuusage = val;
-#endif
+ unlock_rq_dword(cpu);
}
+#endif

/* return total cpu usage (in nanoseconds) of a group */
static u64 cpucg_cpuusage_read(struct cgroup *cgrp, struct cftype *cft)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index b05dd84..0e5e795 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -710,8 +710,6 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
#endif
}

-extern void task_group_charge(struct task_struct *tsk, u64 cputime);
-
#else /* CONFIG_CGROUP_SCHED */

static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
@@ -719,10 +717,14 @@ static inline struct task_group *task_group(struct task_struct *p)
{
return NULL;
}
-static inline void task_group_charge(struct task_struct *tsk, u64 cputime) { }
-
#endif /* CONFIG_CGROUP_SCHED */

+#if defined(CONFIG_CGROUP_SCHED) && !defined(CONFIG_SCHEDSTATS)
+extern void task_group_charge(struct task_struct *tsk, u64 cputime);
+#else
+static inline void task_group_charge(struct task_struct *tsk, u64 cputime) {}
+#endif
+
static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
{
set_task_rq(p, cpu);
--
1.8.1.4


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