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[PATCH] sched: implement cpu_clock(cpu) high-speed time source

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Implement the cpu_clock(cpu) interface for kernel-internal use:
high-speed (but slightly incorrect) per-cpu clock constructed from
sched_clock().

This API, unused at the moment, will be used in the future by blktrace,
by the softlockup-watchdog, by printk and by lockstat.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2007-07-19 21:28:35 +02:00
parent 969bb4e403
commit e436d80085
2 changed files with 24 additions and 0 deletions
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7
include/linux/sched.h
View File

@ -1348,6 +1348,13 @@ static inline int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
#endif
extern unsigned long long sched_clock(void);
/*
* For kernel-internal use: high-speed (but slightly incorrect) per-cpu
* clock constructed from sched_clock():
*/
extern unsigned long long cpu_clock(int cpu);
extern unsigned long long
task_sched_runtime(struct task_struct *task);

17
kernel/sched.c
View File

@ -379,6 +379,23 @@ static inline unsigned long long rq_clock(struct rq *rq)
#define task_rq(p) cpu_rq(task_cpu(p))
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
/*
* For kernel-internal use: high-speed (but slightly incorrect) per-cpu
* clock constructed from sched_clock():
*/
unsigned long long cpu_clock(int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long long now;
unsigned long flags;
spin_lock_irqsave(&rq->lock, flags);
now = rq_clock(rq);
spin_unlock_irqrestore(&rq->lock, flags);
return now;
}
#ifdef CONFIG_FAIR_GROUP_SCHED
/* Change a task's ->cfs_rq if it moves across CPUs */
static inline void set_task_cfs_rq(struct task_struct *p)