From 5f40d804325e925409907e29f46ecb012090b6c2 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Fri, 29 Mar 2013 14:37:43 +0800 Subject: [PATCH] sched/cpuacct: Remove redundant NULL checks in cpuacct_acount_field() 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 Acked-by: Peter Zijlstra Link: http://lkml.kernel.org/r/515536B7.6060602@huawei.com Signed-off-by: Ingo Molnar --- kernel/sched/cpuacct.c | 4 ++-- kernel/sched/cpuacct.h | 5 +++++ 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c index b2aaaba16d46..071ae8d08181 100644 --- a/kernel/sched/cpuacct.c +++ b/kernel/sched/cpuacct.c @@ -237,10 +237,10 @@ void cpuacct_account_field(struct task_struct *p, int index, u64 val) rcu_read_lock(); ca = task_ca(p); - while (ca && (ca != &root_cpuacct)) { + while (ca != &root_cpuacct) { kcpustat = this_cpu_ptr(ca->cpustat); kcpustat->cpustat[index] += val; - ca = parent_ca(ca); + ca = __parent_ca(ca); } rcu_read_unlock(); } diff --git a/kernel/sched/cpuacct.h b/kernel/sched/cpuacct.h index 45c168207fcc..b2f79ad1e524 100644 --- a/kernel/sched/cpuacct.h +++ b/kernel/sched/cpuacct.h @@ -34,6 +34,11 @@ static inline struct cpuacct *task_ca(struct task_struct *tsk) 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) { if (!ca->css.cgroup->parent)