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Commit cb85a6ed authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Thomas Gleixner
Browse files

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



Git commit a25cac51 "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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
Reviewed-by: default avatarSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20120330122308.18720283@de.ibm.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent aa2bf9bc

fs/proc/stat.c

+28 −6
Original line number Diff line number Diff line
@@ -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;