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Commit e436d800 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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



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: default avatarIngo Molnar <mingo@elte.hu>
parent 969bb4e4

include/linux/sched.h

+7 −0
Original line number Diff line number Diff line
@@ -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);

kernel/sched.c

+17 −0
Original line number Diff line number Diff line
@@ -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)