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proc: stats: Use arch_idle_time for idle and iowait times if available

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Git commit a25cac5198 "proc: Consider NO_HZ when printing idle and
iowait times" changes the code for /proc/stat to use get_cpu_idle_time_us
and get_cpu_iowait_time_us if the system is running with nohz enabled.
For architectures which define arch_idle_time (currently s390 only)
this is a change for the worse. The result of arch_idle_time is supposed
to be the exact sleep time of the target cpu and should be used instead
of the value kept by the scheduler.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20120330122308.18720283@de.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Martin Schwidefsky 2012-03-30 12:23:08 +02:00 committed by Thomas Gleixner
parent aa2bf9bc64
commit cb85a6ed67
1 changed files with 28 additions and 6 deletions
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34
fs/proc/stat.c
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@ -18,19 +18,39 @@
#ifndef arch_irq_stat
#define arch_irq_stat() 0
#endif
#ifndef arch_idle_time
#define arch_idle_time(cpu) 0
#endif
#ifdef arch_idle_time
static cputime64_t get_idle_time(int cpu)
{
cputime64_t idle;
idle = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE];
if (cpu_online(cpu) && !nr_iowait_cpu(cpu))
idle += arch_idle_time(cpu);
return idle;
}
static cputime64_t get_iowait_time(int cpu)
{
cputime64_t iowait;
iowait = kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT];
if (cpu_online(cpu) && nr_iowait_cpu(cpu))
iowait += arch_idle_time(cpu);
return iowait;
}
#else
static u64 get_idle_time(int cpu)
{
u64 idle, idle_time = get_cpu_idle_time_us(cpu, NULL);
if (idle_time == -1ULL) {
if (idle_time == -1ULL)
/* !NO_HZ so we can rely on cpustat.idle */
idle = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE];
idle += arch_idle_time(cpu);
} else
else
idle = usecs_to_cputime64(idle_time);
return idle;
@ -49,6 +69,8 @@ static u64 get_iowait_time(int cpu)
return iowait;
}
#endif
static int show_stat(struct seq_file *p, void *v)
{
int i, j;