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sched/cpuacct: Remove redundant NULL checks in cpuacct_acount_field()

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This is a micro optimazation for a hot path.

- We don't need to check if @ca returned from task_ca() is NULL.
- We don't need to check if @ca returned from parent_ca() is NULL.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/515536B7.6060602@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Li Zefan 2013-03-29 14:37:43 +08:00 committed by Ingo Molnar
parent 543bc0e76e
commit 5f40d80432
2 changed files with 7 additions and 2 deletions
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4
kernel/sched/cpuacct.c
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@ -237,10 +237,10 @@ void cpuacct_account_field(struct task_struct *p, int index, u64 val)
rcu_read_lock(); rcu_read_lock();
ca = task_ca(p); ca = task_ca(p);
while (ca && (ca != &root_cpuacct)) { while (ca != &root_cpuacct) {
kcpustat = this_cpu_ptr(ca->cpustat); kcpustat = this_cpu_ptr(ca->cpustat);
kcpustat->cpustat[index] += val; kcpustat->cpustat[index] += val;
ca = parent_ca(ca); ca = __parent_ca(ca);
} }
rcu_read_unlock(); rcu_read_unlock();
} }

5
kernel/sched/cpuacct.h
View File

@ -34,6 +34,11 @@ static inline struct cpuacct *task_ca(struct task_struct *tsk)
struct cpuacct, css); struct cpuacct, css);
} }
static inline struct cpuacct *__parent_ca(struct cpuacct *ca)
{
return cgroup_ca(ca->css.cgroup->parent);
}
static inline struct cpuacct *parent_ca(struct cpuacct *ca) static inline struct cpuacct *parent_ca(struct cpuacct *ca)
{ {
if (!ca->css.cgroup->parent) if (!ca->css.cgroup->parent)