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[PATCH] improve precision of idle time detection.

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Increase the precision of the idle time calculation that is exported
to user space via /sys/devices/system/cpu/cpu<x>/idle_time_us

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2008-12-31 15:11:40 +01:00
parent aa5e97ce4b
commit 6f43092441
4 changed files with 62 additions and 38 deletions
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25
arch/s390/kernel/smp.c
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@ -851,9 +851,11 @@ static ssize_t show_idle_count(struct sys_device *dev,
unsigned long long idle_count;
idle = &per_cpu(s390_idle, dev->id);
spin_lock_irq(&idle->lock);
spin_lock(&idle->lock);
idle_count = idle->idle_count;
spin_unlock_irq(&idle->lock);
if (idle->idle_enter)
idle_count++;
spin_unlock(&idle->lock);
return sprintf(buf, "%llu\n", idle_count);
}
static SYSDEV_ATTR(idle_count, 0444, show_idle_count, NULL);
@ -862,18 +864,17 @@ static ssize_t show_idle_time(struct sys_device *dev,
struct sysdev_attribute *attr, char *buf)
{
struct s390_idle_data *idle;
unsigned long long new_time;
unsigned long long now, idle_time, idle_enter;
idle = &per_cpu(s390_idle, dev->id);
spin_lock_irq(&idle->lock);
if (idle->in_idle) {
new_time = get_clock();
idle->idle_time += new_time - idle->idle_enter;
idle->idle_enter = new_time;
}
new_time = idle->idle_time;
spin_unlock_irq(&idle->lock);
return sprintf(buf, "%llu\n", new_time >> 12);
spin_lock(&idle->lock);
now = get_clock();
idle_time = idle->idle_time;
idle_enter = idle->idle_enter;
if (idle_enter != 0ULL && idle_enter < now)
idle_time += now - idle_enter;
spin_unlock(&idle->lock);
return sprintf(buf, "%llu\n", idle_time >> 12);
}
static SYSDEV_ATTR(idle_time_us, 0444, show_idle_time, NULL);