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Commit 9c2c4802 authored by Ken Chen's avatar Ken Chen Committed by Ingo Molnar
Browse files

schedstat: consolidate per-task cpu runtime stats 



Impact: simplify code

When we turn on CONFIG_SCHEDSTATS, per-task cpu runtime is accumulated
twice. Once in task->se.sum_exec_runtime and once in sched_info.cpu_time.
These two stats are exactly the same.

Given that task->se.sum_exec_runtime is always accumulated by the core
scheduler, sched_info can reuse that data instead of duplicate the accounting.

Signed-off-by: default avatarKen Chen <kenchen@google.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e9515c3c

fs/proc/base.c

+1 −1
Original line number Diff line number Diff line
@@ -347,7 +347,7 @@ static int proc_pid_wchan(struct task_struct *task, char *buffer) 
static int proc_pid_schedstat(struct task_struct *task, char *buffer)

{

	return sprintf(buffer, "%llu %llu %lu\n",

			task->sched_info.cpu_time,

			task->se.sum_exec_runtime,

			task->sched_info.run_delay,

			task->sched_info.pcount);

}

include/linux/sched.h

+1 −2
Original line number Diff line number Diff line
@@ -670,8 +670,7 @@ struct reclaim_state; 
struct sched_info {

	/* cumulative counters */

	unsigned long pcount;	      /* # of times run on this cpu */

	unsigned long long cpu_time,  /* time spent on the cpu */

			   run_delay; /* time spent waiting on a runqueue */

	unsigned long long run_delay; /* time spent waiting on a runqueue */



	/* timestamps */

	unsigned long long last_arrival,/* when we last ran on a cpu */

kernel/delayacct.c

+1 −1
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 
	 */

	t1 = tsk->sched_info.pcount;

	t2 = tsk->sched_info.run_delay;

	t3 = tsk->sched_info.cpu_time;

	t3 = tsk->se.sum_exec_runtime;



	d->cpu_count += t1;

kernel/sched.c

+2 −0
Original line number Diff line number Diff line
@@ -596,6 +596,8 @@ struct rq { 
#ifdef CONFIG_SCHEDSTATS

	/* latency stats */

	struct sched_info rq_sched_info;

	unsigned long long rq_cpu_time;

	/* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */



	/* sys_sched_yield() stats */

	unsigned int yld_exp_empty;

kernel/sched_stats.h

+2 −3
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ static int show_schedstat(struct seq_file *seq, void *v) 
		    rq->yld_act_empty, rq->yld_exp_empty, rq->yld_count,

		    rq->sched_switch, rq->sched_count, rq->sched_goidle,

		    rq->ttwu_count, rq->ttwu_local,

		    rq->rq_sched_info.cpu_time,

		    rq->rq_cpu_time,

		    rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);



		seq_printf(seq, "\n");
@@ -123,7 +123,7 @@ static inline void 
rq_sched_info_depart(struct rq *rq, unsigned long long delta)

{

	if (rq)

		rq->rq_sched_info.cpu_time += delta;

		rq->rq_cpu_time += delta;

}



static inline void
@@ -236,7 +236,6 @@ static inline void sched_info_depart(struct task_struct *t) 
	unsigned long long delta = task_rq(t)->clock -

					t->sched_info.last_arrival;



	t->sched_info.cpu_time += delta;

	rq_sched_info_depart(task_rq(t), delta);



	if (t->state == TASK_RUNNING)