diff options
| author | Li Zefan <lizefan@huawei.com> | 2013-03-29 14:37:29 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-04-10 13:54:18 +0200 |
| commit | 543bc0e76e6bb84300eaf9833edc5a481f788678 (patch) | |
| tree | b3584f05bedffee2bd604fa63d0e8b613cda28d4 /kernel/sched | |
| parent | 1966aaf7d54608e8ddb7ac454b461840e763409a (diff) | |
| download | op-kernel-dev-543bc0e76e6bb84300eaf9833edc5a481f788678.zip op-kernel-dev-543bc0e76e6bb84300eaf9833edc5a481f788678.tar.gz | |
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: Li Zefan <lizefan@huawei.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/515536A9.5000700@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/cpuacct.c | 6 | ||||
| -rw-r--r-- | kernel/sched/cpuacct.h | 2 |
2 files changed, 6 insertions, 2 deletions
diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c index 72bd971..b2aaaba 100644 --- a/kernel/sched/cpuacct.c +++ b/kernel/sched/cpuacct.c @@ -210,9 +210,13 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime) ca = task_ca(tsk); - for (; ca; ca = parent_ca(ca)) { + while (true) { u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); *cpuusage += cputime; + + ca = parent_ca(ca); + if (!ca) + break; } rcu_read_unlock(); diff --git a/kernel/sched/cpuacct.h b/kernel/sched/cpuacct.h index bd0409b..45c1682 100644 --- a/kernel/sched/cpuacct.h +++ b/kernel/sched/cpuacct.h @@ -36,7 +36,7 @@ static inline struct cpuacct *task_ca(struct task_struct *tsk) static inline struct cpuacct *parent_ca(struct cpuacct *ca) { - if (!ca || !ca->css.cgroup->parent) + if (!ca->css.cgroup->parent) return NULL; return cgroup_ca(ca->css.cgroup->parent); } |
