linux/kernel/sched/cpuacct.h
Li Zefan 543bc0e76e 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>
2013-04-10 13:54:18 +02:00

64 lines
1.6 KiB
C

/* Time spent by the tasks of the cpu accounting group executing in ... */
enum cpuacct_stat_index {
CPUACCT_STAT_USER, /* ... user mode */
CPUACCT_STAT_SYSTEM, /* ... kernel mode */
CPUACCT_STAT_NSTATS,
};
#ifdef CONFIG_CGROUP_CPUACCT
#include <linux/cgroup.h>
/* track cpu usage of a group of tasks and its child groups */
struct cpuacct {
struct cgroup_subsys_state css;
/* cpuusage holds pointer to a u64-type object on every cpu */
u64 __percpu *cpuusage;
struct kernel_cpustat __percpu *cpustat;
};
extern struct cgroup_subsys cpuacct_subsys;
extern struct cpuacct root_cpuacct;
/* return cpu accounting group corresponding to this container */
static inline struct cpuacct *cgroup_ca(struct cgroup *cgrp)
{
return container_of(cgroup_subsys_state(cgrp, cpuacct_subsys_id),
struct cpuacct, css);
}
/* return cpu accounting group to which this task belongs */
static inline struct cpuacct *task_ca(struct task_struct *tsk)
{
return container_of(task_subsys_state(tsk, cpuacct_subsys_id),
struct cpuacct, css);
}
static inline struct cpuacct *parent_ca(struct cpuacct *ca)
{
if (!ca->css.cgroup->parent)
return NULL;
return cgroup_ca(ca->css.cgroup->parent);
}
extern void cpuacct_init(void);
extern void cpuacct_charge(struct task_struct *tsk, u64 cputime);
extern void cpuacct_account_field(struct task_struct *p, int index, u64 val);
#else
static inline void cpuacct_init(void)
{
}
static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
}
static inline void
cpuacct_account_field(struct task_struct *p, int index, u64 val)
{
}
#endif