Commit d180c5bc authored by Hidetoshi Seto's avatar Hidetoshi Seto Committed by Ingo Molnar
Browse files

sched: Introduce task_times() to replace task_{u,s}time() pair 



Functions task_{u,s}time() are called in pair in almost all
cases.  However task_stime() is implemented to call task_utime()
from its inside, so such paired calls run task_utime() twice.

It means we do heavy divisions (div_u64 + do_div) twice to get
utime and stime which can be obtained at same time by one set
of divisions.

This patch introduces a function task_times(*tsk, *utime,
*stime) to retrieve utime and stime at once in better, optimized
way.

Signed-off-by: default avatarHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
LKML-Reference: <4B0E16AE.906@jp.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 16bc67ed

fs/proc/array.c

+1 −2
Original line number Diff line number Diff line
@@ -535,8 +535,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, 
	if (!whole) {

		min_flt = task->min_flt;

		maj_flt = task->maj_flt;

		utime = task_utime(task);

		stime = task_stime(task);

		task_times(task, &utime, &stime);

		gtime = task_gtime(task);

	}

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -1723,6 +1723,7 @@ static inline void put_task_struct(struct task_struct *t) 
extern cputime_t task_utime(struct task_struct *p);

extern cputime_t task_stime(struct task_struct *p);

extern cputime_t task_gtime(struct task_struct *p);

extern void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st);



/*

 * Per process flags

kernel/exit.c

+5 −2
Original line number Diff line number Diff line
@@ -91,6 +91,8 @@ static void __exit_signal(struct task_struct *tsk) 
	if (atomic_dec_and_test(&sig->count))

		posix_cpu_timers_exit_group(tsk);

	else {

		cputime_t utime, stime;



		/*

		 * If there is any task waiting for the group exit

		 * then notify it:
@@ -110,8 +112,9 @@ static void __exit_signal(struct task_struct *tsk) 
		 * We won't ever get here for the group leader, since it

		 * will have been the last reference on the signal_struct.

		 */

		sig->utime = cputime_add(sig->utime, task_utime(tsk));

		sig->stime = cputime_add(sig->stime, task_stime(tsk));

		task_times(tsk, &utime, &stime);

		sig->utime = cputime_add(sig->utime, utime);

		sig->stime = cputime_add(sig->stime, stime);

		sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));

		sig->min_flt += tsk->min_flt;

		sig->maj_flt += tsk->maj_flt;

kernel/sched.c

+35 −20
Original line number Diff line number Diff line
@@ -5191,6 +5191,14 @@ cputime_t task_stime(struct task_struct *p) 
{

	return p->stime;

}



void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)

{

	if (ut)

		*ut = task_utime(p);

	if (st)

		*st = task_stime(p);

}

#else



#ifndef nsecs_to_cputime
@@ -5198,41 +5206,48 @@ cputime_t task_stime(struct task_struct *p) 
	msecs_to_cputime(div_u64((__nsecs), NSEC_PER_MSEC))

#endif



cputime_t task_utime(struct task_struct *p)

void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)

{

	cputime_t utime = p->utime, total = utime + p->stime;

	u64 temp;

	cputime_t rtime, utime = p->utime, total = utime + p->stime;



	/*

	 * Use CFS's precise accounting:

	 */

	temp = (u64)nsecs_to_cputime(p->se.sum_exec_runtime);

	rtime = nsecs_to_cputime(p->se.sum_exec_runtime);



	if (total) {

		temp *= utime;

		u64 temp;



		temp = (u64)(rtime * utime);

		do_div(temp, total);

	}

		utime = (cputime_t)temp;

	} else

		utime = rtime;



	/*

	 * Compare with previous values, to keep monotonicity:

	 */

	p->prev_utime = max(p->prev_utime, utime);

	return p->prev_utime;

	p->prev_stime = max(p->prev_stime, rtime - p->prev_utime);



	if (ut)

		*ut = p->prev_utime;

	if (st)

		*st = p->prev_stime;

}



cputime_t task_utime(struct task_struct *p)

{

	cputime_t utime;

	task_times(p, &utime, NULL);

	return utime;

}



cputime_t task_stime(struct task_struct *p)

{

	cputime_t stime;



	/*

	 * Use CFS's precise accounting. (we subtract utime from

	 * the total, to make sure the total observed by userspace

	 * grows monotonically - apps rely on that):

	 */

	stime = nsecs_to_cputime(p->se.sum_exec_runtime) - task_utime(p);



	if (stime >= 0)

		p->prev_stime = max(p->prev_stime, stime);



	return p->prev_stime;

	task_times(p, NULL, &stime);

	return stime;

}

#endif

kernel/sys.c

+1 −2
Original line number Diff line number Diff line
@@ -1346,8 +1346,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r) 
	utime = stime = cputime_zero;



	if (who == RUSAGE_THREAD) {

		utime = task_utime(current);

		stime = task_stime(current);

		task_times(current, &utime, &stime);

		accumulate_thread_rusage(p, r);

		maxrss = p->signal->maxrss;

		goto out;

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