mirror of
https://github.com/torvalds/linux.git
synced 2024-12-11 05:33:09 +00:00
a130e8fbc7
/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
46 lines
1.0 KiB
C
46 lines
1.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/fs.h>
|
|
#include <linux/init.h>
|
|
#include <linux/proc_fs.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/time.h>
|
|
#include <linux/time_namespace.h>
|
|
#include <linux/kernel_stat.h>
|
|
|
|
static int uptime_proc_show(struct seq_file *m, void *v)
|
|
{
|
|
struct timespec64 uptime;
|
|
struct timespec64 idle;
|
|
u64 idle_nsec;
|
|
u32 rem;
|
|
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);
|
|
}
|
|
|
|
ktime_get_boottime_ts64(&uptime);
|
|
timens_add_boottime(&uptime);
|
|
|
|
idle.tv_sec = div_u64_rem(idle_nsec, NSEC_PER_SEC, &rem);
|
|
idle.tv_nsec = rem;
|
|
seq_printf(m, "%lu.%02lu %lu.%02lu\n",
|
|
(unsigned long) uptime.tv_sec,
|
|
(uptime.tv_nsec / (NSEC_PER_SEC / 100)),
|
|
(unsigned long) idle.tv_sec,
|
|
(idle.tv_nsec / (NSEC_PER_SEC / 100)));
|
|
return 0;
|
|
}
|
|
|
|
static int __init proc_uptime_init(void)
|
|
{
|
|
proc_create_single("uptime", 0, NULL, uptime_proc_show);
|
|
return 0;
|
|
}
|
|
fs_initcall(proc_uptime_init);
|