From patchwork series 498198

https://patchwork.ozlabs.org//project/linuxppc-dev/list/?series=498198

Author: Fox Snowpatch

arch/powerpc/kernel/time.c

@@ -376,6 +376,47 @@ void vtime_task_switch(struct task_struct *prev)
 		acct->starttime = acct0->starttime;
 	}
 }
+
+#ifdef CONFIG_NO_HZ_COMMON
+/**
+ * vtime_reset - Fast forward vtime entry clocks
+ *
+ * Called from dynticks idle IRQ entry to fast-forward the clocks to current time
+ * so that the IRQ time is still accounted by vtime while nohz cputime is paused.
+ */
+void vtime_reset(void)
+{
+	struct cpu_accounting_data *acct = get_accounting(current);
+
+	acct->starttime = mftb();
+#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
+	acct->startspurr = read_spurr(acct->starttime);
+#endif
+}
+
+/**
+ * vtime_dyntick_start - Inform vtime about entry to idle-dynticks
+ *
+ * Called when idle enters in dyntick mode. The idle cputime that elapsed so far
+ * is accumulated and the tick subsystem takes over the idle cputime accounting.
+ */
+void vtime_dyntick_start(void)
+{
+	vtime_account_idle(current);
+}
+
+/**
+ * vtime_dyntick_stop - Inform vtime about exit from idle-dynticks
+ *
+ * Called when idle exits from dyntick mode. The vtime entry clocks are
+ * fast-forward to current time so that idle accounting restarts elapsing from
+ * now.
+ */
+void vtime_dyntick_stop(void)
+{
+	vtime_reset();
+}
+#endif /* CONFIG_NO_HZ_COMMON */
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 
 void __no_kcsan __delay(unsigned long loops)

arch/s390/include/asm/idle.h

@@ -8,10 +8,12 @@
 #ifndef _S390_IDLE_H
 #define _S390_IDLE_H
 
+#include <linux/percpu-defs.h>
 #include <linux/types.h>
 #include <linux/device.h>
 
 struct s390_idle_data {
+	bool	      idle_dyntick;
 	unsigned long idle_count;
 	unsigned long idle_time;
 	unsigned long clock_idle_enter;

arch/s390/kernel/idle.c

@@ -31,7 +31,10 @@ void account_idle_time_irq(void)
 	/* Account time spent with enabled wait psw loaded as idle time. */
 	__atomic64_add(idle_time, &idle->idle_time);
 	__atomic64_add_const(1, &idle->idle_count);
-	account_idle_time(cputime_to_nsecs(idle_time));
+
+	/* Dyntick idle time accounted by nohz/scheduler */
+	if (!idle->idle_dyntick)
+		account_idle_time(cputime_to_nsecs(idle_time));
 }
 
 void noinstr arch_cpu_idle(void)

arch/s390/kernel/vtime.c

@@ -17,6 +17,7 @@
 #include <asm/vtimer.h>
 #include <asm/vtime.h>
 #include <asm/cpu_mf.h>
+#include <asm/idle.h>
 #include <asm/smp.h>
 
 #include "entry.h"
@@ -110,6 +111,16 @@ static void account_system_index_scaled(struct task_struct *p, u64 cputime,
 	account_system_index_time(p, cputime_to_nsecs(cputime), index);
 }
 
+static inline void vtime_reset_last_update(struct lowcore *lc)
+{
+	asm volatile(
+		"	stpt	%0\n"	/* Store current cpu timer value */
+		"	stckf	%1"	/* Store current tod clock value */
+		: "=Q" (lc->last_update_timer),
+		  "=Q" (lc->last_update_clock)
+		: : "cc");
+}
+
 /*
  * Update process times based on virtual cpu times stored by entry.S
  * to the lowcore fields user_timer, system_timer & steal_clock.
@@ -121,12 +132,9 @@ static int do_account_vtime(struct task_struct *tsk)
 
 	timer = lc->last_update_timer;
 	clock = lc->last_update_clock;
-	asm volatile(
-		"	stpt	%0\n"	/* Store current cpu timer value */
-		"	stckf	%1"	/* Store current tod clock value */
-		: "=Q" (lc->last_update_timer),
-		  "=Q" (lc->last_update_clock)
-		: : "cc");
+
+	vtime_reset_last_update(lc);
+
 	clock = lc->last_update_clock - clock;
 	timer -= lc->last_update_timer;
 
@@ -239,6 +247,43 @@ void vtime_account_hardirq(struct task_struct *tsk)
 	get_lowcore()->hardirq_timer += vtime_delta();
 }
 
+#ifdef CONFIG_NO_HZ_COMMON
+/**
+ * vtime_reset - Fast forward vtime entry clocks
+ *
+ * Called from dynticks idle IRQ entry to fast-forward the clocks to current time
+ * so that the IRQ time is still accounted by vtime while nohz cputime is paused.
+ */
+void vtime_reset(void)
+{
+	vtime_reset_last_update(get_lowcore());
+}
+
+/**
+ * vtime_dyntick_start - Inform vtime about entry to idle-dynticks
+ *
+ * Called when idle enters in dyntick mode. The idle cputime that elapsed so far
+ * is flushed and the tick subsystem takes over the idle cputime accounting.
+ */
+void vtime_dyntick_start(void)
+{
+	__this_cpu_write(s390_idle.idle_dyntick, true);
+	vtime_flush(current);
+}
+
+/**
+ * vtime_dyntick_stop - Inform vtime about exit from idle-dynticks
+ *
+ * Called when idle exits from dyntick mode. The vtime entry clocks are
+ * fast-forward to current time and idle accounting resumes.
+ */
+void vtime_dyntick_stop(void)
+{
+	vtime_reset_last_update(get_lowcore());
+	__this_cpu_write(s390_idle.idle_dyntick, false);
+}
+#endif /* CONFIG_NO_HZ_COMMON */
+
 /*
  * Sorted add to a list. List is linear searched until first bigger
  * element is found.

drivers/cpufreq/cpufreq.c

@@ -130,38 +130,11 @@ struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy)
 }
 EXPORT_SYMBOL_GPL(get_governor_parent_kobj);
 
-static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
-{
-	struct kernel_cpustat kcpustat;
-	u64 cur_wall_time;
-	u64 idle_time;
-	u64 busy_time;
-
-	cur_wall_time = jiffies64_to_nsecs(get_jiffies_64());
-
-	kcpustat_cpu_fetch(&kcpustat, cpu);
-
-	busy_time = kcpustat.cpustat[CPUTIME_USER];
-	busy_time += kcpustat.cpustat[CPUTIME_SYSTEM];
-	busy_time += kcpustat.cpustat[CPUTIME_IRQ];
-	busy_time += kcpustat.cpustat[CPUTIME_SOFTIRQ];
-	busy_time += kcpustat.cpustat[CPUTIME_STEAL];
-	busy_time += kcpustat.cpustat[CPUTIME_NICE];
-
-	idle_time = cur_wall_time - busy_time;
-	if (wall)
-		*wall = div_u64(cur_wall_time, NSEC_PER_USEC);
-
-	return div_u64(idle_time, NSEC_PER_USEC);
-}
-
 u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy)
 {
 	u64 idle_time = get_cpu_idle_time_us(cpu, io_busy ? wall : NULL);
 
-	if (idle_time == -1ULL)
-		return get_cpu_idle_time_jiffy(cpu, wall);
-	else if (!io_busy)
+	if (!io_busy)
 		idle_time += get_cpu_iowait_time_us(cpu, wall);
 
 	return idle_time;

drivers/cpufreq/cpufreq_governor.c

@@ -105,7 +105,7 @@ void gov_update_cpu_data(struct dbs_data *dbs_data)
 			j_cdbs->prev_cpu_idle = get_cpu_idle_time(j, &j_cdbs->prev_update_time,
 								  dbs_data->io_is_busy);
 			if (dbs_data->ignore_nice_load)
-				j_cdbs->prev_cpu_nice = kcpustat_field(&kcpustat_cpu(j), CPUTIME_NICE, j);
+				j_cdbs->prev_cpu_nice = kcpustat_field(CPUTIME_NICE, j);
 		}
 	}
 }
@@ -165,7 +165,7 @@ unsigned int dbs_update(struct cpufreq_policy *policy)
 		j_cdbs->prev_cpu_idle = cur_idle_time;
 
 		if (ignore_nice) {
-			u64 cur_nice = kcpustat_field(&kcpustat_cpu(j), CPUTIME_NICE, j);
+			u64 cur_nice = kcpustat_field(CPUTIME_NICE, j);
 
 			idle_time += div_u64(cur_nice - j_cdbs->prev_cpu_nice, NSEC_PER_USEC);
 			j_cdbs->prev_cpu_nice = cur_nice;
@@ -539,7 +539,7 @@ int cpufreq_dbs_governor_start(struct cpufreq_policy *policy)
 		j_cdbs->prev_load = 0;
 
 		if (ignore_nice)
-			j_cdbs->prev_cpu_nice = kcpustat_field(&kcpustat_cpu(j), CPUTIME_NICE, j);
+			j_cdbs->prev_cpu_nice = kcpustat_field(CPUTIME_NICE, j);
 	}
 
 	gov->start(policy);

drivers/macintosh/rack-meter.c

@@ -87,7 +87,7 @@ static inline u64 get_cpu_idle_time(unsigned int cpu)
 		 kcpustat->cpustat[CPUTIME_IOWAIT];
 
 	if (rackmeter_ignore_nice)
-		retval += kcpustat_field(kcpustat, CPUTIME_NICE, cpu);
+		retval += kcpustat_field(CPUTIME_NICE, cpu);
 
 	return retval;
 }

fs/proc/stat.c

@@ -22,38 +22,6 @@
 #define arch_irq_stat() 0
 #endif
 
-u64 get_idle_time(struct kernel_cpustat *kcs, int cpu)
-{
-	u64 idle, idle_usecs = -1ULL;
-
-	if (cpu_online(cpu))
-		idle_usecs = get_cpu_idle_time_us(cpu, NULL);
-
-	if (idle_usecs == -1ULL)
-		/* !NO_HZ or cpu offline so we can rely on cpustat.idle */
-		idle = kcs->cpustat[CPUTIME_IDLE];
-	else
-		idle = idle_usecs * NSEC_PER_USEC;
-
-	return idle;
-}
-
-static u64 get_iowait_time(struct kernel_cpustat *kcs, int cpu)
-{
-	u64 iowait, iowait_usecs = -1ULL;
-
-	if (cpu_online(cpu))
-		iowait_usecs = get_cpu_iowait_time_us(cpu, NULL);
-
-	if (iowait_usecs == -1ULL)
-		/* !NO_HZ or cpu offline so we can rely on cpustat.iowait */
-		iowait = kcs->cpustat[CPUTIME_IOWAIT];
-	else
-		iowait = iowait_usecs * NSEC_PER_USEC;
-
-	return iowait;
-}
-
 static void show_irq_gap(struct seq_file *p, unsigned int gap)
 {
 	static const char zeros[] = " 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0";
@@ -105,8 +73,8 @@ static int show_stat(struct seq_file *p, void *v)
 		user		+= cpustat[CPUTIME_USER];
 		nice		+= cpustat[CPUTIME_NICE];
 		system		+= cpustat[CPUTIME_SYSTEM];
-		idle		+= get_idle_time(&kcpustat, i);
-		iowait		+= get_iowait_time(&kcpustat, i);
+		idle		+= cpustat[CPUTIME_IDLE];
+		iowait		+= cpustat[CPUTIME_IOWAIT];
 		irq		+= cpustat[CPUTIME_IRQ];
 		softirq		+= cpustat[CPUTIME_SOFTIRQ];
 		steal		+= cpustat[CPUTIME_STEAL];
@@ -146,8 +114,8 @@ static int show_stat(struct seq_file *p, void *v)
 		user		= cpustat[CPUTIME_USER];
 		nice		= cpustat[CPUTIME_NICE];
 		system		= cpustat[CPUTIME_SYSTEM];
-		idle		= get_idle_time(&kcpustat, i);
-		iowait		= get_iowait_time(&kcpustat, i);
+		idle		= cpustat[CPUTIME_IDLE];
+		iowait		= cpustat[CPUTIME_IOWAIT];
 		irq		= cpustat[CPUTIME_IRQ];
 		softirq		= cpustat[CPUTIME_SOFTIRQ];
 		steal		= cpustat[CPUTIME_STEAL];

fs/proc/uptime.c

@@ -18,12 +18,8 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 	int i;
 
 	idle_nsec = 0;
-	for_each_possible_cpu(i) {
-		struct kernel_cpustat kcs;
-
-		kcpustat_cpu_fetch(&kcs, i);
-		idle_nsec += get_idle_time(&kcs, i);
-	}
+	for_each_possible_cpu(i)
+		idle_nsec += kcpustat_field(CPUTIME_IDLE, i);
 
 	ktime_get_boottime_ts64(&uptime);
 	timens_add_boottime(&uptime);