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Commit ac78bc71 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull scheduler fixes from Ingo Molnar:
 "Two cputime fixes - hopefully the last ones"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/cputime: Resync steal time when guest & host lose sync
  sched/cputime: Fix NO_HZ_FULL getrusage() monotonicity regression
parents 0dcb7b6f 03cbc732

kernel/sched/cputime.c

+25 −8
Original line number Diff line number Diff line
@@ -263,6 +263,11 @@ void account_idle_time(cputime_t cputime) 
		cpustat[CPUTIME_IDLE] += (__force u64) cputime;

}



/*

 * When a guest is interrupted for a longer amount of time, missed clock

 * ticks are not redelivered later. Due to that, this function may on

 * occasion account more time than the calling functions think elapsed.

 */

static __always_inline cputime_t steal_account_process_time(cputime_t maxtime)

{

#ifdef CONFIG_PARAVIRT
@@ -371,7 +376,7 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick, 
	 * idle, or potentially user or system time. Due to rounding,

	 * other time can exceed ticks occasionally.

	 */

	other = account_other_time(cputime);

	other = account_other_time(ULONG_MAX);

	if (other >= cputime)

		return;

	cputime -= other;
@@ -486,7 +491,7 @@ void account_process_tick(struct task_struct *p, int user_tick) 
	}



	cputime = cputime_one_jiffy;

	steal = steal_account_process_time(cputime);

	steal = steal_account_process_time(ULONG_MAX);



	if (steal >= cputime)

		return;
@@ -516,7 +521,7 @@ void account_idle_ticks(unsigned long ticks) 
	}



	cputime = jiffies_to_cputime(ticks);

	steal = steal_account_process_time(cputime);

	steal = steal_account_process_time(ULONG_MAX);



	if (steal >= cputime)

		return;
@@ -614,19 +619,25 @@ static void cputime_adjust(struct task_cputime *curr, 
	stime = curr->stime;

	utime = curr->utime;



	if (utime == 0) {

		stime = rtime;

	/*

	 * If either stime or both stime and utime are 0, assume all runtime is

	 * userspace. Once a task gets some ticks, the monotonicy code at

	 * 'update' will ensure things converge to the observed ratio.

	 */

	if (stime == 0) {

		utime = rtime;

		goto update;

	}



	if (stime == 0) {

		utime = rtime;

	if (utime == 0) {

		stime = rtime;

		goto update;

	}



	stime = scale_stime((__force u64)stime, (__force u64)rtime,

			    (__force u64)(stime + utime));



update:

	/*

	 * Make sure stime doesn't go backwards; this preserves monotonicity

	 * for utime because rtime is monotonic.
@@ -649,7 +660,6 @@ static void cputime_adjust(struct task_cputime *curr, 
		stime = rtime - utime;

	}



update:

	prev->stime = stime;

	prev->utime = utime;

out:
@@ -694,6 +704,13 @@ static cputime_t get_vtime_delta(struct task_struct *tsk) 
	unsigned long now = READ_ONCE(jiffies);

	cputime_t delta, other;



	/*

	 * Unlike tick based timing, vtime based timing never has lost

	 * ticks, and no need for steal time accounting to make up for

	 * lost ticks. Vtime accounts a rounded version of actual

	 * elapsed time. Limit account_other_time to prevent rounding

	 * errors from causing elapsed vtime to go negative.

	 */

	delta = jiffies_to_cputime(now - tsk->vtime_snap);

	other = account_other_time(delta);

	WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);