[PATCH] Add hierarchical accounting to cpu accounting controller

From: Bharata B Rao
Date: Thu Oct 23 2008 - 01:43:21 EST


Add hierarchical accounting to cpu accounting controller

Currently, while charging the task's cputime to its accounting group,
the accounting group hierarchy isn't updated. This patch charges the cputime
of a task to its accounting group and all its parent accounting groups.

Reported-by: Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Bharata B Rao <bharata@xxxxxxxxxxxxxxxxxx>
CC: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxx>
---
kernel/sched.c | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)

--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -9131,10 +9131,15 @@ struct cpuacct {
struct cgroup_subsys_state css;
/* cpuusage holds pointer to a u64-type object on every cpu */
u64 *cpuusage;
+ struct cpuacct *parent;
};

+static struct cpuacct init_cpuacct_group;
struct cgroup_subsys cpuacct_subsys;

+#define for_each_cpuacct_group(ca) \
+ for (; ca; ca = ca->parent)
+
/* return cpu accounting group corresponding to this container */
static inline struct cpuacct *cgroup_ca(struct cgroup *cgrp)
{
@@ -9153,17 +9158,28 @@ static inline struct cpuacct *task_ca(st
static struct cgroup_subsys_state *cpuacct_create(
struct cgroup_subsys *ss, struct cgroup *cgrp)
{
- struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
+ struct cpuacct *ca;

- if (!ca)
- return ERR_PTR(-ENOMEM);
+ if (!cgrp->parent) {
+ /* This is early initialization for the top cgroup */
+ ca = &init_cpuacct_group;
+ } else {
+ ca = kzalloc(sizeof(*ca), GFP_KERNEL);
+ if (!ca)
+ return ERR_PTR(-ENOMEM);
+ }

ca->cpuusage = alloc_percpu(u64);
if (!ca->cpuusage) {
- kfree(ca);
+ if (cgrp->parent)
+ kfree(ca);
return ERR_PTR(-ENOMEM);
}

+ if (cgrp->parent) {
+ ca->css.cgroup = cgrp;
+ ca->parent = cgroup_ca(cgrp->parent);
+ }
return &ca->css;
}

@@ -9243,14 +9259,16 @@ static int cpuacct_populate(struct cgrou
static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
struct cpuacct *ca;
+ int cpu;

if (!cpuacct_subsys.active)
return;

+ cpu = task_cpu(tsk);
ca = task_ca(tsk);
- if (ca) {
- u64 *cpuusage = percpu_ptr(ca->cpuusage, task_cpu(tsk));

+ for_each_cpuacct_group(ca) {
+ u64 *cpuusage = percpu_ptr(ca->cpuusage, cpu);
*cpuusage += cputime;
}
}
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