proc: stats: Use arch_idle_time for idle and iowait times if available
Git commit a25cac5198d4ff28 "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>
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 6a0c62d..64c3b31 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -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 @@
return iowait;
}
+#endif
+
static int show_stat(struct seq_file *p, void *v)
{
int i, j;