Commit 543bc0e7 authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar

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

This is a micro optimization for the hot path.

- We don't need to check if @ca is NULL in parent_ca().
- We don't need to check if @ca is NULL in the beginning of the for loop.
Signed-off-by: default avatarLi Zefan <lizefan@huawei.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/515536A9.5000700@huawei.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 1966aaf7
...@@ -210,9 +210,13 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime) ...@@ -210,9 +210,13 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime)
ca = task_ca(tsk); ca = task_ca(tsk);
for (; ca; ca = parent_ca(ca)) { while (true) {
u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
*cpuusage += cputime; *cpuusage += cputime;
ca = parent_ca(ca);
if (!ca)
break;
} }
rcu_read_unlock(); rcu_read_unlock();
......
...@@ -36,7 +36,7 @@ static inline struct cpuacct *task_ca(struct task_struct *tsk) ...@@ -36,7 +36,7 @@ static inline struct cpuacct *task_ca(struct task_struct *tsk)
static inline struct cpuacct *parent_ca(struct cpuacct *ca) static inline struct cpuacct *parent_ca(struct cpuacct *ca)
{ {
if (!ca || !ca->css.cgroup->parent) if (!ca->css.cgroup->parent)
return NULL; return NULL;
return cgroup_ca(ca->css.cgroup->parent); return cgroup_ca(ca->css.cgroup->parent);
} }
......
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