[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, 16 insertions, 0 deletions

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 70c57378f426..cc7c4ba0774d 100644
--- a/arch/s390/kernel/process.c
+++ b/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 |