ACPI: C-States: accounting of sleep states

Track the actual time spent in C-States (C2 upwards, we can't determine this
for C1), not only the number of invocations.  This is especially useful for
dynamic ticks / "tickless systems", but is also of interest on normal systems,
as any interrupt activity leads to C-States being exited, not only the timer
interrupt.

The time is being measured in PM timer ticks, so an increase by one equals 279
nanoseconds.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 7 insertions, 4 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 89d3fd4c3cd2..6d1e238e2375 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -322,8 +322,6 @@ static void acpi_processor_idle(void)
                 cx = &pr->power.states[ACPI_STATE_C1];
 #endif
 
-        cx->usage++;
-
         /*
          * Sleep:
          * ------
@@ -430,6 +428,9 @@ static void acpi_processor_idle(void)
                 local_irq_enable();
                 return;
         }
+        cx->usage++;
+        if ((cx->type != ACPI_STATE_C1) && (sleep_ticks > 0))
+                cx->time += sleep_ticks;
 
         next_state = pr->power.state;
 
@@ -1053,9 +1054,10 @@ static int acpi_processor_power_seq_show(struct seq_file *seq, void *offset)
                 else
                         seq_puts(seq, "demotion[--] ");
 
-                seq_printf(seq, "latency[%03d] usage[%08d]\n",
+                seq_printf(seq, "latency[%03d] usage[%08d] duration[%020llu]\n",
                            pr->power.states[i].latency,
-                           pr->power.states[i].usage);
+                           pr->power.states[i].usage,
+                           pr->power.states[i].time);
         }
 
       end:
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 77371b3cdc44..9dd5b75961f8 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -62,6 +62,7 @@ struct acpi_processor_cx {
         u32 latency_ticks;
         u32 power;
         u32 usage;
+        u64 time;
         struct acpi_processor_cx_policy promotion;
         struct acpi_processor_cx_policy demotion;
 };