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Commit b27f03d4 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched: make use of precise accounting for /proc task stats 



make use of CFS's precise accounting to drive /proc/<pid>/stat statistics.

this code was co-authored by:

 Balbir Singh <balbir@linux.vnet.ibm.com>
 Dmitry Adamushko <dmitry.adamushko@gmail.com>
 Ingo Molnar <mingo@elte.hu>

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarDmitry Adamushko <dmitry.adamushko@gmail.com>
parent 1b9f19c2

fs/proc/array.c

+47 −10
Original line number Diff line number Diff line
@@ -310,6 +310,41 @@ int proc_pid_status(struct task_struct *task, char * buffer) 
	return buffer - orig;

}



static clock_t task_utime(struct task_struct *p)

{

	clock_t utime = cputime_to_clock_t(p->utime),

		total = utime + cputime_to_clock_t(p->stime);

	u64 temp;



	/*

	 * Use CFS's precise accounting:

	 */

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



	if (total) {

		temp *= utime;

		do_div(temp, total);

	}

	utime = (clock_t)temp;



	return utime;

}



static clock_t task_stime(struct task_struct *p)

{

	clock_t stime = cputime_to_clock_t(p->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 = nsec_to_clock_t(p->se.sum_exec_runtime) - task_utime(p);



	return stime;

}





static int do_task_stat(struct task_struct *task, char * buffer, int whole)

{

	unsigned long vsize, eip, esp, wchan = ~0UL;
@@ -324,7 +359,8 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole) 
	unsigned long long start_time;

	unsigned long cmin_flt = 0, cmaj_flt = 0;

	unsigned long  min_flt = 0,  maj_flt = 0;

	cputime_t cutime, cstime, utime, stime;

	cputime_t cutime, cstime;

	clock_t utime, stime;

	unsigned long rsslim = 0;

	char tcomm[sizeof(task->comm)];

	unsigned long flags;
@@ -342,7 +378,8 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole) 


	sigemptyset(&sigign);

	sigemptyset(&sigcatch);

	cutime = cstime = utime = stime = cputime_zero;

	cutime = cstime = cputime_zero;

	utime = stime = 0;



	rcu_read_lock();

	if (lock_task_sighand(task, &flags)) {
@@ -368,15 +405,15 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole) 
			do {

				min_flt += t->min_flt;

				maj_flt += t->maj_flt;

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

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

				utime += task_utime(t);

				stime += task_stime(t);

				t = next_thread(t);

			} while (t != task);



			min_flt += sig->min_flt;

			maj_flt += sig->maj_flt;

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

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

			utime += cputime_to_clock_t(sig->utime);

			stime += cputime_to_clock_t(sig->stime);

		}



		sid = signal_session(sig);
@@ -392,8 +429,8 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole) 
	if (!whole) {

		min_flt = task->min_flt;

		maj_flt = task->maj_flt;

		utime = task->utime;

		stime = task->stime;

		utime = task_utime(task);

		stime = task_stime(task);

	}



	/* scale priority and nice values from timeslices to -20..20 */
@@ -424,8 +461,8 @@ static int do_task_stat(struct task_struct *task, char * buffer, int whole) 
		cmin_flt,

		maj_flt,

		cmaj_flt,

		cputime_to_clock_t(utime),

		cputime_to_clock_t(stime),

		utime,

		stime,

		cputime_to_clock_t(cutime),

		cputime_to_clock_t(cstime),

		priority,