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Subject[patch 02/10] Add per-cpu idle time / idle count sysfs attributes.
From: Heiko Carstens <heiko.carstens@de.ibm.com>

Add two new sysfs entries per cpu: idle_count and idle_time.
idle_count contains the number of times a cpu went into idle state.
idle_time contains the time a cpu spent in idle state in microseconds.
This can be used e.g. by powertop to tell how often idle state is
entered and left.

# cat /sys/devices/system/cpu/cpu0/idle_count
504
# cat /sys/devices/system/cpu/cpu0/idle_time
469734037 us

Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
arch/s390/kernel/process.c | 16 +++++++++++
arch/s390/kernel/smp.c | 63 ++++++++++++++++++++++++++++++++++++++++++---
include/asm-s390/cpu.h | 25 +++++++++++++++++
3 files changed, 101 insertions(+), 3 deletions(-)
Index: quilt-2.6/arch/s390/kernel/process.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/process.c
+++ quilt-2.6/arch/s390/kernel/process.c
@@ -44,6 +44,7 @@
#include <asm/processor.h>
#include <asm/irq.h>
#include <asm/timer.h>
+#include <asm/cpu.h>

asmlinkage void ret_from_fork(void) asm ("ret_from_fork");

@@ -91,6 +92,14 @@ EXPORT_SYMBOL(unregister_idle_notifier);

void do_monitor_call(struct pt_regs *regs, long interruption_code)
{
+ struct s390_idle_data *idle;
+
+ idle = &__get_cpu_var(s390_idle);
+ spin_lock(&idle->lock);
+ idle->idle_time += get_clock() - idle->idle_enter;
+ idle->in_idle = 0;
+ spin_unlock(&idle->lock);
+
/* disable monitor call class 0 */
__ctl_clear_bit(8, 15);

@@ -105,6 +114,7 @@ extern void s390_handle_mcck(void);
static void default_idle(void)
{
int cpu, rc;
+ struct s390_idle_data *idle;

/* CPU is going idle. */
cpu = smp_processor_id();
@@ -142,6 +152,12 @@ static void default_idle(void)
return;
}

+ idle = &__get_cpu_var(s390_idle);
+ spin_lock(&idle->lock);
+ idle->idle_count++;
+ idle->in_idle = 1;
+ idle->idle_enter = get_clock();
+ spin_unlock(&idle->lock);
trace_hardirqs_on();
/* Wait for external, I/O or machine check interrupt. */
__load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
Index: quilt-2.6/arch/s390/kernel/smp.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/smp.c
+++ quilt-2.6/arch/s390/kernel/smp.c
@@ -42,6 +42,7 @@
#include <asm/tlbflush.h>
#include <asm/timer.h>
#include <asm/lowcore.h>
+#include <asm/cpu.h>

/*
* An array with a pointer the lowcore of every CPU.
@@ -494,6 +495,8 @@ int __cpuinit start_secondary(void *cpuv
return 0;
}

+DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
+
static void __init smp_create_idle(unsigned int cpu)
{
struct task_struct *p;
@@ -506,6 +509,7 @@ static void __init smp_create_idle(unsig
if (IS_ERR(p))
panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
current_set[cpu] = p;
+ spin_lock_init(&(&per_cpu(s390_idle, cpu))->lock);
}

static int cpu_stopped(int cpu)
@@ -724,6 +728,7 @@ void __init smp_prepare_boot_cpu(void)
cpu_set(0, cpu_online_map);
S390_lowcore.percpu_offset = __per_cpu_offset[0];
current_set[0] = current;
+ spin_lock_init(&(&__get_cpu_var(s390_idle))->lock);
}

void __init smp_cpus_done(unsigned int max_cpus)
@@ -756,22 +761,71 @@ static ssize_t show_capability(struct sy
}
static SYSDEV_ATTR(capability, 0444, show_capability, NULL);

+static ssize_t show_idle_count(struct sys_device *dev, char *buf)
+{
+ struct s390_idle_data *idle;
+ unsigned long long idle_count;
+
+ idle = &per_cpu(s390_idle, dev->id);
+ spin_lock_irq(&idle->lock);
+ idle_count = idle->idle_count;
+ spin_unlock_irq(&idle->lock);
+ return sprintf(buf, "%llu\n", idle_count);
+}
+static SYSDEV_ATTR(idle_count, 0444, show_idle_count, NULL);
+
+static ssize_t show_idle_time(struct sys_device *dev, char *buf)
+{
+ struct s390_idle_data *idle;
+ unsigned long long new_time;
+
+ 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 us\n", new_time >> 12);
+}
+static SYSDEV_ATTR(idle_time, 0444, show_idle_time, NULL);
+
+static struct attribute *cpu_attrs[] = {
+ &attr_capability.attr,
+ &attr_idle_count.attr,
+ &attr_idle_time.attr,
+ NULL,
+};
+
+static struct attribute_group cpu_attr_group = {
+ .attrs = cpu_attrs,
+};
+
static int __cpuinit smp_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
unsigned int cpu = (unsigned int)(long)hcpu;
struct cpu *c = &per_cpu(cpu_devices, cpu);
struct sys_device *s = &c->sysdev;
+ struct s390_idle_data *idle;

switch (action) {
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
- if (sysdev_create_file(s, &attr_capability))
+ idle = &per_cpu(s390_idle, cpu);
+ spin_lock_irq(&idle->lock);
+ idle->idle_enter = 0;
+ idle->idle_time = 0;
+ idle->idle_count = 0;
+ spin_unlock_irq(&idle->lock);
+ if (sysfs_create_group(&s->kobj, &cpu_attr_group))
return NOTIFY_BAD;
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
- sysdev_remove_file(s, &attr_capability);
+ sysfs_remove_group(&s->kobj, &cpu_attr_group);
break;
}
return NOTIFY_OK;
@@ -784,6 +838,7 @@ static struct notifier_block __cpuinitda
static int __init topology_init(void)
{
int cpu;
+ int rc;

register_cpu_notifier(&smp_cpu_nb);

@@ -796,7 +851,9 @@ static int __init topology_init(void)
if (!cpu_online(cpu))
continue;
s = &c->sysdev;
- sysdev_create_file(s, &attr_capability);
+ rc = sysfs_create_group(&s->kobj, &cpu_attr_group);
+ if (rc)
+ return rc;
}
return 0;
}
Index: quilt-2.6/include/asm-s390/cpu.h
===================================================================
--- /dev/null
+++ quilt-2.6/include/asm-s390/cpu.h
@@ -0,0 +1,25 @@
+/*
+ * include/asm-s390/cpu.h
+ *
+ * Copyright IBM Corp. 2007
+ * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#ifndef _ASM_S390_CPU_H_
+#define _ASM_S390_CPU_H_
+
+#include <linux/types.h>
+#include <linux/percpu.h>
+#include <linux/spinlock.h>
+
+struct s390_idle_data {
+ spinlock_t lock;
+ unsigned int in_idle;
+ unsigned long long idle_count;
+ unsigned long long idle_enter;
+ unsigned long long idle_time;
+};
+
+DECLARE_PER_CPU(struct s390_idle_data, s390_idle);
+
+#endif /* _ASM_S390_CPU_H_ */
--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.

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