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[S390] rework idle code

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Whenever the cpu loads an enabled wait PSW it will appear as idle to the
underlying host system. The code in default_idle calls vtime_stop_cpu
which does the necessary voodoo to get the cpu time accounting right.
The udelay code just loads an enabled wait PSW. To correct this rework
the vtime_stop_cpu/vtime_start_cpu logic and move the difficult parts
to entry[64].S, vtime_stop_cpu can now be called from anywhere and
vtime_start_cpu is gone. The correction of the cpu time during wakeup
from an enabled wait PSW is done with a critical section in entry[64].S.
As vtime_start_cpu is gone, s390_idle_check can be removed as well.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2012-03-11 11:59:27 -04:00
parent 8b646bd759
commit 4c1051e37a
13 changed files with 214 additions and 214 deletions
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46
arch/s390/kernel/smp.c
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@@ -972,22 +972,16 @@ static DEVICE_ATTR(capability, 0444, show_capability, NULL);
static ssize_t show_idle_count(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct s390_idle_data *idle;
struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
unsigned long long idle_count;
unsigned int sequence;
idle = &per_cpu(s390_idle, dev->id);
repeat:
sequence = idle->sequence;
smp_rmb();
if (sequence & 1)
goto repeat;
idle_count = idle->idle_count;
if (idle->idle_enter)
idle_count++;
smp_rmb();
if (idle->sequence != sequence)
goto repeat;
do {
sequence = ACCESS_ONCE(idle->sequence);
idle_count = ACCESS_ONCE(idle->idle_count);
if (ACCESS_ONCE(idle->idle_enter))
idle_count++;
} while ((sequence & 1) || (idle->sequence != sequence));
return sprintf(buf, "%llu\n", idle_count);
}
static DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
@@ -995,24 +989,18 @@ static DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
static ssize_t show_idle_time(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct s390_idle_data *idle;
unsigned long long now, idle_time, idle_enter;
struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
unsigned long long now, idle_time, idle_enter, idle_exit;
unsigned int sequence;
idle = &per_cpu(s390_idle, dev->id);
now = get_clock();
repeat:
sequence = idle->sequence;
smp_rmb();
if (sequence & 1)
goto repeat;
idle_time = idle->idle_time;
idle_enter = idle->idle_enter;
if (idle_enter != 0ULL && idle_enter < now)
idle_time += now - idle_enter;
smp_rmb();
if (idle->sequence != sequence)
goto repeat;
do {
now = get_clock();
sequence = ACCESS_ONCE(idle->sequence);
idle_time = ACCESS_ONCE(idle->idle_time);
idle_enter = ACCESS_ONCE(idle->idle_enter);
idle_exit = ACCESS_ONCE(idle->idle_exit);
} while ((sequence & 1) || (idle->sequence != sequence));
idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0;
return sprintf(buf, "%llu\n", idle_time >> 12);
}
static DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);