sched/cpuacct: Simplify the cpuacct code
- Use for() instead of while() loop in some functions
to make the code simpler.
- Use this_cpu_ptr() instead of per_cpu_ptr() to make the code
cleaner and a bit faster.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/d8a7ef9592f55224630cb26dea239f05b6398a4e.1458187654.git.zhaolei@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 9c2bbf7..434c2fa 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -238,23 +238,10 @@
void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
struct cpuacct *ca;
- int cpu;
-
- cpu = task_cpu(tsk);
rcu_read_lock();
-
- ca = task_ca(tsk);
-
- while (true) {
- u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
- *cpuusage += cputime;
-
- ca = parent_ca(ca);
- if (!ca)
- break;
- }
-
+ for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
+ *this_cpu_ptr(ca->cpuusage) += cputime;
rcu_read_unlock();
}
@@ -263,18 +250,13 @@
*
* Note: it's the caller that updates the account of the root cgroup.
*/
-void cpuacct_account_field(struct task_struct *p, int index, u64 val)
+void cpuacct_account_field(struct task_struct *tsk, int index, u64 val)
{
- struct kernel_cpustat *kcpustat;
struct cpuacct *ca;
rcu_read_lock();
- ca = task_ca(p);
- while (ca != &root_cpuacct) {
- kcpustat = this_cpu_ptr(ca->cpustat);
- kcpustat->cpustat[index] += val;
- ca = parent_ca(ca);
- }
+ for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))
+ this_cpu_ptr(ca->cpustat)->cpustat[index] += val;
rcu_read_unlock();
}