[S390] Add per-cpu idle time / idle count sysfs attributes.

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>

1 files changed, 60 insertions, 3 deletions

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 35edbef1d222..ba3fff06fad1 100644
--- a/arch/s390/kernel/smp.c
+++ b/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 *cpuvoid)
         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(unsigned int cpu)
         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 sys_device *dev, char *buf)
 }
 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 __cpuinitdata smp_cpu_nb = {
 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;
 }