Revert "sched/cputime: use sched idle time accounting"

hulk inclusion
category: bugfix
bugzilla: 13257
CVE: NA

-------------------------------------------------

Avoid compile error.

This reverts commit 4c289dfb931da642f094f33c44c01d561b62f1c2.

fs/proc/stat.c

@@ -45,16 +45,14 @@ static u64 get_iowait_time(int cpu)
 
 #else
 
-u64 get_idle_time(int cpu)
+static u64 get_idle_time(int cpu)
 {
 	u64 idle, idle_usecs = -1ULL;
 
 	if (cpu_online(cpu))
 		idle_usecs = get_cpu_idle_time_us(cpu, NULL);
 
-	if (idle_usecs == -1ULL && use_sched_idle_time)
-		return sched_get_idle_time(cpu);
-	else if (idle_usecs == -1ULL)
+	if (idle_usecs == -1ULL)
 		/* !NO_HZ or cpu offline so we can rely on cpustat.idle */
 		idle = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE];
 	else
@@ -97,19 +95,9 @@ static int show_stat(struct seq_file *p, void *v)
 	getboottime64(&boottime);
 
 	for_each_possible_cpu(i) {
-		if (use_sched_idle_time && cpu_online(i)) {
-			u64 u = 0, s = 0;
-
-			sched_idle_time_adjust(i, &u, &s);
-
-			user += u;
-			system += s;
-		} else {
-			user += kcpustat_cpu(i).cpustat[CPUTIME_USER];
-			system += kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
-		}
-
+		user += kcpustat_cpu(i).cpustat[CPUTIME_USER];
 		nice += kcpustat_cpu(i).cpustat[CPUTIME_NICE];
+		system += kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
 		idle += get_idle_time(i);
 		iowait += get_iowait_time(i);
 		irq += kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
@@ -143,13 +131,9 @@ static int show_stat(struct seq_file *p, void *v)
 
 	for_each_online_cpu(i) {
 		/* Copy values here to work around gcc-2.95.3, gcc-2.96 */
-		if (use_sched_idle_time) {
-			sched_idle_time_adjust(i, &user, &system);
-		} else {
-			user = kcpustat_cpu(i).cpustat[CPUTIME_USER];
-			system = kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
-		}
+		user = kcpustat_cpu(i).cpustat[CPUTIME_USER];
 		nice = kcpustat_cpu(i).cpustat[CPUTIME_NICE];
+		system = kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
 		idle = get_idle_time(i);
 		iowait = get_iowait_time(i);
 		irq = kcpustat_cpu(i).cpustat[CPUTIME_IRQ];

include/linux/sched/cputime.h

@@ -186,9 +186,4 @@ static inline void prev_cputime_init(struct prev_cputime *prev)
 extern unsigned long long
 task_sched_runtime(struct task_struct *task);
 
-extern int use_sched_idle_time;
-extern int sched_idle_time_adjust(int cpu, u64 *utime, u64 *stime);
-extern unsigned long long sched_get_idle_time(int cpu);
-extern u64 get_idle_time(int cpu);
-
 #endif /* _LINUX_SCHED_CPUTIME_H */

include/linux/sched/nohz.h

@@ -22,11 +22,9 @@ static inline void nohz_balance_enter_idle(int cpu) { }
 #endif
 
 #ifdef CONFIG_NO_HZ_COMMON
-extern unsigned long tick_nohz_active;
 void calc_load_nohz_start(void);
 void calc_load_nohz_stop(void);
 #else
-#define tick_nohz_active (0)
 static inline void calc_load_nohz_start(void) { }
 static inline void calc_load_nohz_stop(void) { }
 #endif /* CONFIG_NO_HZ_COMMON */

kernel/sched/core.c

@@ -5913,17 +5913,6 @@ static struct kmem_cache *task_group_cache __read_mostly;
 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
 DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);
 
-static __init void rq_cputime_init(void)
-{
-	int cpu;
-	struct rq_cputime *rq_cputime;
-
-	for_each_possible_cpu(cpu) {
-		rq_cputime = &per_cpu(rq_cputimes, cpu);
-		raw_spin_lock_init(&rq_cputime->lock);
-	}
-}
-
 void __init sched_init(void)
 {
 	int i, j;
@@ -6085,9 +6074,6 @@ void __init sched_init(void)
 
 	init_schedstats();
 
-	if (use_sched_idle_time)
-		rq_cputime_init();
-
 	scheduler_running = 1;
 }
 

kernel/sched/cputime.c

@@ -567,74 +567,6 @@ static u64 scale_stime(u64 stime, u64 rtime, u64 total)
 	return scaled;
 }
 
-int use_sched_idle_time __read_mostly;
-DEFINE_PER_CPU_SHARED_ALIGNED(struct rq_cputime, rq_cputimes);
-
-static int __init sched_idle_time_setup(char *str)
-{
-	use_sched_idle_time = 1;
-
-	return 0;
-}
-early_param("use-sched-idle-time", sched_idle_time_setup);
-
-int sched_idle_time_adjust(int cpu, u64 *utime, u64 *stime)
-{
-	struct rq_cputime *rq_cputime = &per_cpu(rq_cputimes, cpu);
-	struct cputime *prev = &rq_cputime->cpu_prev_time;
-	struct cputime *last = &rq_cputime->cpu_last_time;
-	u64 ut, st, delta, delta_ut, delta_st;
-
-	raw_spin_lock(&rq_cputime->lock);
-
-	delta = cpu_clock(cpu) - get_idle_time(cpu)
-		- (prev->utime + prev->stime);
-
-	ut = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
-	st = kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
-
-	delta_ut = ut - last->utime;
-	delta_st = st - last->stime;
-
-	if (unlikely((s64)delta <= 0))
-		goto out;
-
-	if (delta_st == 0) {
-		prev->utime += delta;
-	} else if (delta_ut == 0) {
-		prev->stime += delta;
-	} else {
-		delta_st = scale_stime(delta_st, delta, delta_ut + delta_st);
-
-		if (unlikely(delta_st > delta))
-			delta_st = delta;
-
-		prev->stime += delta_st;
-		prev->utime += delta - delta_st;
-	}
-
-out:
-	last->utime = ut;
-	last->stime = st;
-
-	*utime = prev->utime;
-	*stime = prev->stime;
-
-	raw_spin_unlock(&rq_cputime->lock);
-
-	return 0;
-}
-
-unsigned long long sched_get_idle_time(int cpu)
-{
-	struct rq_cputime *rt = &per_cpu(rq_cputimes, cpu);
-
-	if (is_idle_task(curr_task(cpu)))
-		return rt->sum_idle_time + cpu_clock(cpu) - rt->last_entry_idle;
-	else
-		return rt->sum_idle_time;
-}
-
 /*
  * Adjust tick based cputime random precision against scheduler runtime
  * accounting.

kernel/sched/sched.h

@@ -919,21 +919,6 @@ struct rq {
 #endif
 };
 
-struct cputime {
-	u64 utime;
-	u64 stime;
-};
-
-struct rq_cputime {
-	raw_spinlock_t lock;
-	unsigned long long sum_idle_time;
-	unsigned long long last_entry_idle;
-	struct cputime cpu_prev_time;
-	struct cputime cpu_last_time;
-};
-
-DECLARE_PER_CPU(struct rq_cputime, rq_cputimes);
-
 static inline int cpu_of(struct rq *rq)
 {
 #ifdef CONFIG_SMP

kernel/sched/stats.h

 /* SPDX-License-Identifier: GPL-2.0 */
-#include <linux/sched/cputime.h>
 
 #ifdef CONFIG_SCHEDSTATS
 
@@ -154,20 +153,6 @@ __sched_info_switch(struct rq *rq, struct task_struct *prev, struct task_struct
 static inline void
 sched_info_switch(struct rq *rq, struct task_struct *prev, struct task_struct *next)
 {
-	if (use_sched_idle_time && !tick_nohz_active) {
-		struct rq *rq = task_rq(prev);
-		struct rq_cputime *rq_cputime = this_cpu_ptr(&rq_cputimes);
-		unsigned long long now = cpu_clock(cpu_of(rq)), delta = 0;
-
-		if (prev == rq->idle) {
-			delta = now - rq_cputime->last_entry_idle;
-			rq_cputime->sum_idle_time += delta;
-		}
-
-		if (next == rq->idle)
-			rq_cputime->last_entry_idle = now;
-	}
-
 	if (unlikely(sched_info_on()))
 		__sched_info_switch(rq, prev, next);
 }

kernel/time/tick-internal.h

@@ -149,12 +149,14 @@ static inline void tick_nohz_init(void) { }
 #endif
 
 #ifdef CONFIG_NO_HZ_COMMON
+extern unsigned long tick_nohz_active;
 extern void timers_update_nohz(void);
 # ifdef CONFIG_SMP
 extern struct static_key_false timers_migration_enabled;
 # endif
 #else /* CONFIG_NO_HZ_COMMON */
 static inline void timers_update_nohz(void) { }
+#define tick_nohz_active (0)
 #endif
 
 DECLARE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases);