Commit-ID: 5f40d804325e925409907e29f46ecb012090b6c2
Gitweb: http://git.kernel.org/tip/5f40d804325e925409907e29f46ecb012090b6c2
Author: Li Zefan <lizefan@xxxxxxxxxx>
AuthorDate: Fri, 29 Mar 2013 14:37:43 +0800
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 10 Apr 2013 13:54:18 +0200
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 <lizefan@xxxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/515536B7.6060602@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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 b2aaaba..071ae8d 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 45c1682..b2f79ad1 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)
--
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