linux-stable/include/linux/kernel_stat.h
Josh Don a130e8fbc7 fs/proc/uptime.c: Fix idle time reporting in /proc/uptime
/proc/uptime reports idle time by reading the CPUTIME_IDLE field from
the per-cpu kcpustats. However, on NO_HZ systems, idle time is not
continually updated on idle cpus, leading this value to appear
incorrectly small.

/proc/stat performs an accounting update when reading idle time; we
can use the same approach for uptime.

With this patch, /proc/stat and /proc/uptime now agree on idle time.
Additionally, the following shows idle time tick up consistently on an
idle machine:

  (while true; do cat /proc/uptime; sleep 1; done) | awk '{print $2-prev; prev=$2}'

Reported-by: Luigi Rizzo <lrizzo@google.com>
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lkml.kernel.org/r/20210827165438.3280779-1-joshdon@google.com
2021-10-05 15:51:35 +02:00

118 lines
3 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_KERNEL_STAT_H
#define _LINUX_KERNEL_STAT_H
#include <linux/smp.h>
#include <linux/threads.h>
#include <linux/percpu.h>
#include <linux/cpumask.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/vtime.h>
#include <asm/irq.h>
/*
* 'kernel_stat.h' contains the definitions needed for doing
* some kernel statistics (CPU usage, context switches ...),
* used by rstatd/perfmeter
*/
enum cpu_usage_stat {
CPUTIME_USER,
CPUTIME_NICE,
CPUTIME_SYSTEM,
CPUTIME_SOFTIRQ,
CPUTIME_IRQ,
CPUTIME_IDLE,
CPUTIME_IOWAIT,
CPUTIME_STEAL,
CPUTIME_GUEST,
CPUTIME_GUEST_NICE,
NR_STATS,
};
struct kernel_cpustat {
u64 cpustat[NR_STATS];
};
struct kernel_stat {
unsigned long irqs_sum;
unsigned int softirqs[NR_SOFTIRQS];
};
DECLARE_PER_CPU(struct kernel_stat, kstat);
DECLARE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
/* Must have preemption disabled for this to be meaningful. */
#define kstat_this_cpu this_cpu_ptr(&kstat)
#define kcpustat_this_cpu this_cpu_ptr(&kernel_cpustat)
#define kstat_cpu(cpu) per_cpu(kstat, cpu)
#define kcpustat_cpu(cpu) per_cpu(kernel_cpustat, cpu)
extern unsigned long long nr_context_switches(void);
extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu);
extern void kstat_incr_irq_this_cpu(unsigned int irq);
static inline void kstat_incr_softirqs_this_cpu(unsigned int irq)
{
__this_cpu_inc(kstat.softirqs[irq]);
}
static inline unsigned int kstat_softirqs_cpu(unsigned int irq, int cpu)
{
return kstat_cpu(cpu).softirqs[irq];
}
/*
* Number of interrupts per specific IRQ source, since bootup
*/
extern unsigned int kstat_irqs_usr(unsigned int irq);
/*
* Number of interrupts per cpu, since bootup
*/
static inline unsigned int kstat_cpu_irqs_sum(unsigned int cpu)
{
return kstat_cpu(cpu).irqs_sum;
}
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
extern u64 kcpustat_field(struct kernel_cpustat *kcpustat,
enum cpu_usage_stat usage, int cpu);
extern void kcpustat_cpu_fetch(struct kernel_cpustat *dst, int cpu);
#else
static inline u64 kcpustat_field(struct kernel_cpustat *kcpustat,
enum cpu_usage_stat usage, int cpu)
{
return kcpustat->cpustat[usage];
}
static inline void kcpustat_cpu_fetch(struct kernel_cpustat *dst, int cpu)
{
*dst = kcpustat_cpu(cpu);
}
#endif
extern void account_user_time(struct task_struct *, u64);
extern void account_guest_time(struct task_struct *, u64);
extern void account_system_time(struct task_struct *, int, u64);
extern void account_system_index_time(struct task_struct *, u64,
enum cpu_usage_stat);
extern void account_steal_time(u64);
extern void account_idle_time(u64);
extern u64 get_idle_time(struct kernel_cpustat *kcs, int cpu);
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
static inline void account_process_tick(struct task_struct *tsk, int user)
{
vtime_flush(tsk);
}
#else
extern void account_process_tick(struct task_struct *, int user);
#endif
extern void account_idle_ticks(unsigned long ticks);
#endif /* _LINUX_KERNEL_STAT_H */